While there are many legitimate uses for this software, adversaries are also finding ways to use them for command and control in their campaigns.

Tuesday, April 2, 2024 08:00

*   Remote system management/desktop access tools such as AnyDesk and TeamViewer have grown in popularity since 2020. While there are many legitimate uses for this software, adversaries are also finding ways to use them for command and control in their campaigns.
*   There is no easy way to effectively block all unauthorized remote management tools, but security can be greatly improved through a combination of policy and technical controls.
*   Early warning alerts can be configured to alert defenders to remote management software activity that may have circumvented the technical controls.

**The remote management/access software problem**

Since 2020, the use of remote system management/access tools such as AnyDesk and TeamViewer has exploded in popularity due to forced work-from-home during the COVID-19 pandemic.

Whether used by an IT help desk technician to fix a user’s remote system or by co-workers for collaboration, these tools play an essential role in most corporations’ digital functions. However, this convenience comes at a cost. These tools introduce the ability for an adversary to potentially take full remote control of a system, are easy to download and install, and can be very difficult to detect since they are considered legitimate software. 

Further complicating the task of recognizing the malicious use of these tools, many organizations struggle to combat “shadow IT” in which individual users or overly proactive IT personnel might install unauthorized remote management tools to accomplish a benign goal.

Cisco Talos Incident Response (Talos IR) is seeing adversaries capitalize on this opportunity in the wild. We recently noted in our Quarterly Trends report for the third quarter of 2023, “AnyDesk was observed in all ransomware and pre-ransomware engagements \[. . .\], underscoring its role in ransomware affiliates' attack chains.”

While AnyDesk is a legitimate application, it highlights the tremendous value that can be gained through a security program that intentionally focuses on preventing unauthorized use of these tools. Talos is referencing AnyDesk for the purposes of this blog post, but any remote management tool is at risk of these exploits. There are several policy changes, technical countermeasures and security alerts that admins and defenders can use to ensure that AnyDesk, and similar pieces of software, are only used for legitimate purposes when deployed.

Adopting one, or at most two, approved remote management solutions will allow the organization to thoroughly test and deploy in the most secure possible configuration.

If possible, integration with other organizational technology such as Active Directory or multi-factor authentication (MFA) will provide additional layers of protection and verification. Tying the approved remote management solutions into these already structured security solutions can make it easier to build “early warning” detections and alerts around unauthorized connectivity and use.

Once a solution is approved and championed for the organization, other remote management/access tools should be explicitly banned by policy. Ideally, this should be accompanied by a software inventory audit and published guidance on approved/non-approved software for the organization. Training and consistent enforcement of this policy will help reduce the “shadow IT” noise in the environment and leave network defenders with more time to investigate true anomalies.

**Technical controls**

While very worthwhile, preventing unauthorized use of these tools is not simple. First, the scores of commercially available remote access tools make it difficult to address every option an adversary might use. Many of those tools are frequently updated, meaning that blocking the executables by their hash value is not as effective. 

Adversaries also commonly rename the executables, meaning that filename blocks aren’t going to be helpful, either. 

Many popular solutions operate over common ports and protocols, such as ports 80 and 443, making them difficult to block at the firewall, and remote access tool creators often decline to publish their central server IP addresses due to frequently changing resolutions, which limits the effectiveness of static IP address blocks. A combination of approaches and techniques is necessary to limit the opportunity for an adversary to use remote access/management tools in any given environment.

**DNS security controls**

One of the most effective methods for detecting, and sometimes blocking, the activities of unauthorized remote management/access software, is by auditing and blocking DNS queries associated with these tools.

If your organization uses Cisco Umbrella for DNS security, it’s fairly easy to review and block DNS queries related to unauthorized traffic.

To review what might already be on your network, log into the Umbrella console and view “Reporting > App Discovery > Unreviewed Apps,” filtered by the “Collaboration” and “IT Services Management” categories, this is an excellent starting point to identify unexpected remote access software.

Simply clicking “Block this app” gives the administrator the ability to block future DNS requests associated with any particular result. If you prefer to take an even more proactive approach, going to “Policies > Policy Components > Application Settings” allows you to search all applications currently categorized by Umbrella, whether they have been seen on your network or not, and block them by policy. Again, the “Collaboration” and “IT Services Management” categories should be the areas of focus for policy review.

As with all of these technical controls, there are a few limitations. The first major caveat is that this only works if the DNS queries are evaluated by your security stack. In the case of DNS traffic from a home user’s system not traveling over the corporate network, the activity would be invisible. The second major caveat is that some remote management software has direct peer-to-peer capabilities, meaning the software might not send a DNS query to an easily identifiable domain when initiating a connection. 

**Firewall controls**

While less scalable and reliable, basic IP address blocking can be beneficial for preventing unauthorized remote software connections. Some vendors list static IP addresses for their central servers on their support sites that can be leveraged to control this access. However, many vendor IP addresses change periodically, making the task a bit challenging.

Another potentially fruitful approach to firewall traffic blocking is by port number. For example, TeamViewer prefers to use port 5938, although it can fall back on the practically unblockable port 443. While blocking port 5938 would not stop the connection, a properly configured alert would provide defenders with an early warning that TeamViewer was trying to connect out.

Some firewalls also provide additional functionality around session content, similar to Umbrella’s capabilities. Firewalls such as Cisco’s Meraki provide an allow/block URL listing that can be configured to prevent connectivity to unapproved remote management software sites. Cisco Meraki can provide content filtering options that may be helpful in blocking remote management/access sites.

Administrators should consider that firewall controls to combat unauthorized remote software management connections can have unintended consequences and should be heavily tested and piloted prior to implementation.

Verify that IP addresses are dedicated to that application prior to blocking in order to avoid blocking Content Delivery Network (CDN) nodes or other cloud computing shared resources. 

Finally, network segmentation or micro-segmentation can be useful in blocking unauthorized remote management software usage. For instance, categorizing and organizing server resources separate from workstation resources can allow for more tailored options around blocking all unnecessary traffic at the firewall, include that which may be associated with remote management tools. Some organizations already do this well by integrating with group policy configurations.

**Host-based controls****Windows Defender Application Control (WDAC) and AppLocker**

Of all the controls discussed in this post, WDAC and AppLocker are the only ones that can offer almost 100 percent protection against unauthorized remote management/access software execution.

In their most secure configuration, which allows only pre-approved software to run, users or adversaries can't run unexpected executables. However, this comes at a cost, as the approved software baseline maintenance level of effort can be high, and the user experience can be very limited if they are not allowed to install applications as needed.

WDAC and AppLocker offer considerable flexibility in their policies, so some organizations choose to only lock down their critical servers, such as domain controllers, which leaves user system policies more flexible. This approach has benefits far beyond simply blocking remote access/management software, as it will stop most malware from executing, as well.

Keep in mind that, while WDAC is currently more difficult to configure, it has more advanced capabilities and Microsoft is positioning it as the replacement for AppLocker. At the moment, AppLocker is receiving security updates, but no new feature updates.

**Registry filename blocks**

It is possible to block remote management/access software execution by filename via a registry “DisallowRun” key. However, Talos IR does not recommend this approach, except as a containment measure during incident response, since it is not scalable as a preventative measure and is trivially easy to bypass by renaming the executable or modifying the registry. 

**EDR blocks**

Almost every modern EDR can block file hashes, which gives defenders the capability to block the hashes associated with remote management/access software installers and/or installed executables. However, similarly to the filename GPO blocks, this is not scalable or reliable as a proactive measure, since every new version of every software distribution will have a new hash value. This measure should be restricted to containment during incident response only. 

Some EDR solutions offer methods to block vulnerable or unauthorized software, albeit with significant caveats regarding the limitations of those capabilities. The authors of this article have not tested those capabilities but note them here for the sake of completeness.

**Host-based firewalls**

The recommendations for host-based firewall rules are much the same as standalone firewalls, covered above. These can be useful where administrators expect users to roam outside of the boundary of the corporate network, such as home workers off the corporate VPN or using a split-tunnel VPN implementation. 

**Administrator permission restriction**

Restricting administrator permissions so that most users cannot conduct administrator actions on their work computer, such as installing remote access/management software, can help limit an adversary’s ability to install this software after the initial compromise.

Applying the principle of least privilege, which includes both locking down local administrator permissions and limiting the permissions of users’ domain accounts, is considered standard best practice.

**NAC controls**

While network access control (NAC) solutions do not directly block the use of remote management software, they can ensure that all other technical controls are working properly before admitting an endpoint to the network. If the device is a rogue system or lacks EDR, for example, NAC would prevent it from joining.

Another benefit offered by a NAC solution is software version enforcement through custom rules. In Cisco ISE, for example, there are Posture Checks. Organizations can use this to ensure that only the approved version(s) of their approved remote management tool are allowed on the network, directly addressing the threat of an adversary introducing an older version of the approved solution to the network for malicious purposes.

**Alerts and forensics**

Due to the complexity of implementing all these controls, detection rules can serve as a backup in case an adversary finds a way to circumvent the previous mitigations we discussed. The possibilities for these “tripwire” detections are endless, and SOCs/threat-hunting teams should continuously think of ways to improve them, but some ideas are listed below.

**Central log collection**

The first prerequisite for any successful detections is to have centralized log aggregation. At the very minimum, this should ingest firewall logs, EDR alerts and Windows Event logs for key servers. 

**SIEM alerts for suspicious strings**

Setting up a simple alert that triggers upon observation of strings associated with unauthorized remote access/management software product names (e.g., “AnyDesk”) can be an effective way to proactively identify unexpected product installations that were not otherwise blocked.

For example, an MSI installation would generate an Event 11707 entry in the Windows Application Event logs containing the software product name. If the SIEM were ingesting and evaluating those event logs, it would fire an alert, thereby alerting the SOC to a potential installation. This rule would need to be tuned to avoid excessive false positives, but it could result in a valuable early detection method. 

**SIEM alerts for firewall blocks on unique ports**

Enhanced alerting may be necessary to draw a SOC’s attention to firewall blocks associated with remote management/access traffic. Firewalls continuously block traffic, generally dropping thousands or millions of packets per hour. With that in mind, SOCs are not alerted every time a firewall rule drops traffic — especially if the rule that drops the traffic is the Implicit Deny rule blocking all traffic that was not specifically allowed. However, if an internal host attempts to communicate over a port dedicated to remote access/management software, that might merit attention from the SOC. 

It's worth considering creating an SIEM rule that alerts on any firewall block event involving outbound traffic to certain key ports, for example, 5938 (associated with TeamViewer). That alert, while an indication that the network blocks are working as intended, would be a good indication that the SOC needs to investigate the system originating the traffic.

The level of effort required to properly secure remote management/access software is daunting. However, the frequency of use by adversaries makes that effort a necessity. In the wrong hands, these tools serve as a ready-made command and control mechanism. If an organization can afford to secure its VPN solution, it should almost certainly devote resources to locking down unauthorized remote management software, as well.

Adversaries are leveraging remote access tools now more than ever — here’s how to stop them

Welcome to this week’s threat source newsletter with Jon out, you’ve got me as your substitute teacher. 

I’m taking you back to those halcyon days of youth and that moment when you found out that you had a sub that day...

Thursday, March 28, 2024 10:00

Welcome to this week’s threat source newsletter with Jon out, you’ve got me as your substitute teacher. 

I’m taking you back to those halcyon days of youth and that moment when you found out that you had a sub that day, will I be the teacher that just rolls in the TV cart and delivers the single greatest blast of freedom that you can have in a classroom, or will I be the teacher that strolls into your 4th grade class and is appalled that you aren’t already conversant in Dostoevsky? Neither. Today I will be the old wizened oracle offering advice and attempting to answer one of the most asked questions I receive at public speaking engagements. So pull up a desk and don’t make that high pitched sound with a wet finger on the basket underneath the seat, because I know the old magicks.  

The number one question that I field after public speaking is “Why did they let you out of your cage to talk to normal people?” and honestly, I don’t really have an answer I just hope that no one notices. The next question is invariably a variation of “How did you become a threat hunter?”, “How do I get a job in cyber security?”, “How do I get a gig within Talos?” The answer is simply – be curious. Intellectual curiosity is the key. I’ll take it a step further when talking specifically about Talos and quote Walt Whitman (via Ted Lasso) and say, “Be curious, not judgmental” because being a positive part of the culture is as important as the deep arcane knowledge and skills that you need to get your foot in the door at Talos.  

There are a lot of paths that you can take in security and the various skill sets along each path vary but curiosity will carry you through each one. A lot of people will tell you to follow your passion and I will vehemently disagree; I will say to follow your aptitude. As you learn and grow within the field, you’ll find that some things come easily, don’t fight the wind in that scenario be the willow. If you are extremely early in your journey, find the helpers. There are tons of super helpful people, sites, and resources available to get you started and finding them is easy if you are curious. Attend a BSides or local security group like AHA. Install Snort and start learning what traffic looks like on the wire and create custom signatures. Install Kali and break things, in your own environment please. Combine the two and see where it will take you. If you are further along in your journey and are interested in taking the next step from analyst to malware research or reverse engineering, you can start with hasherezade's 1001 nights and see if you have the aptitude to follow that path. Don’t be afraid to try something and fail. Don’t expect to be good from the start. Don’t be afraid to ask questions and admit that you don’t know something – the most important things I’ve picked up usually come from “I don’t know, could you teach me?”.  

In the end there are truly almost as many paths as there are people doing the jobs. It’s crazy how varied the backgrounds on our teams are but curiosity is rampant.  

**The one big thing **

The one big thing is that clearly, I’m substituting, and all is normal in the security world. Vulns continue to be exploited, security vendors continue to be consolidated, and everything is as it was in the world. THISISFINEDOTGIF.  

**Why do I care? **

Because it’s what keeps us up at night. That and a warm cup of Liber-Tea.  

**So now what? **

Now we deliver Managed Democracy on Hell Divers 2 – together.  

**Top security headlines of the week **

A newly discovered vulnerability baked into Apple’s M-series of chips allows attackers to extract secret keys from Macs when they perform widely used cryptographic operations, academic researchers have revealed in a paper published Thursday. (Ars Technica, Wired    

Metasploit has announced the release of Metasploit Framework 6.4 which features several improvements and a new feature for Windows Meterpreter that allows for searching a process's memory for user-specified needles with support for regular expressions. (Rapid 7) 

**Can’t get enough Talos? **

*   Cisco Closes $28B Splunk Deal: 5 Big AI, Security And Partner Things To Know 
*   Beers With Talos: The old people episode 
*   Dissecting a complex vulnerability and achieving arbitrary code execution in Ichitaro Word 

**Upcoming events where you can find Talos **

**Botconf** **(April 23 - 26)** 

_Nice, Côte d'Azur, France_

> _This presentation from Chetan Raghuprasad details the Supershell C2 framework. Threat actors are using this framework massively and creating botnets with the Supershell implants._

**CARO Workshop 2024** **(May 1 - 3)** 

_Arlington, Virginia_

> Over the past year, we’ve observed a substantial uptick in attacks by YoroTrooper, a relatively nascent espionage-oriented threat actor operating against the Commonwealth of Independent Countries (CIS) since at least 2022. Asheer Malhotra's presentation at CARO 2024 will provide an overview of their various campaigns detailing the commodity and custom-built malware employed by the actor, their discovery and evolution in tactics. He will present a timeline of successful intrusions carried out by YoroTrooper targeting high-value individuals associated with CIS government agencies over the last two years.

**RSA** **(May 6 - 9)** 

_San Francisco, California_ 

**Most prevalent malware files from Talos telemetry over the past week **

**SHA 256:** 7b3ec2365a64d9a9b2452c22e82e6d6ce2bb6dbc06c6720951c9570a5cd46fe5   
**MD5:** ff1b6bb151cf9f671c929a4cbdb64d86   
**Typical Filename:** endpoint.query   
**Claimed Product:** Endpoint-Collector   
**Detection Name:** W32.File.MalParent 

**SHA 256:** 9f1f11a708d393e0a4109ae189bc64f1f3e312653dcf317a2bd406f18ffcc507    
**MD5:** 2915b3f8b703eb744fc54c81f4a9c67f    
**Typical Filename:** VID001.exe    
**Claimed Product:** N/A    
**Detection Name:** Win.Worm.Coinminer::1201 

**SHA 256:** a31f222fc283227f5e7988d1ad9c0aecd66d58bb7b4d8518ae23e110308dbf91    
**MD5:** 7bdbd180c081fa63ca94f9c22c457376   
**Typical Filename:** c0dwjdi6a.dll   
**Claimed Product:** N/A    
**Detection Name:** Trojan.GenericKD.33515991 

**SHA 256:** 0e2263d4f239a5c39960ffa6b6b688faa7fc3075e130fe0d4599d5b95ef20647   
**MD5:** bbcf7a68f4164a9f5f5cb2d9f30d9790   
**Typical Filename:** bbcf7a68f4164a9f5f5cb2d9f30d9790.vir   
**Claimed Product:** N/A   
**Detection Name:** Win.Dropper.Scar::1201 

**SHA 256:** e38c53aedf49017c47725e4912fc7560e1c8ece2633c05057b22fd4a8ed28eb3   
**MD5:** c16df0bfc6fda86dbfa8948a566d32c1   
**Typical Filename:** CEPlus.docm   
**Claimed Product:** N/A    
**Detection Name:** Doc.Downloader.Pwshell::mash.sr.sbx.vioc

Enter the substitute teacher

In the case of pig butchering scams, it’s not really anything that can be solved by a cybersecurity solution or sold in a package.

Thursday, March 21, 2024 14:00

Whether you want to call them “catfishing,” “pig butchering” or just good ‘old-fashioned “social engineering,” romance scams have been around forever.  

I was first introduced to them through the MTV show “Catfish,” but recently they seem to be making headlines as the term “pig butchering” enters the public lexicon. John Oliver recently covered it on “Last Week Tonight,” which means everyone my age with an HBO account heard about it a few weeks ago. And one of my favorite podcasts going, “Search Engine,” just covered it in an episode. 

The concept of “pig butchering” scams generally follows the same chain of events: 

*   An unknown phone number texts or messages a target with a generally harmless message, usually asking for a random name disguised as an “Oops, wrong number!” text. 
*   When the target responds, the actor tries to strike up a conversation with a friendly demeanor. 
*   If the conversation persists, they usually evolve into “love bombing,” including compliments, friendly advice, ego-boosting, and saying flattering things about any photos the target has sent. 
*   Sometimes, the relationship may turn romantic. 
*   The scammer eventually “butchers” the “pig” that has been “fattened up” to that point, scamming them into handing over money, usually in the form of a phony cryptocurrency app, or just straight up asking for the target to send the scammer money somehow. 

There are a few twists and turns along the way based on the exact scammer, but that’s generally how it works. What I think is important to remember is that this specific method of separating users from their money is not actually new.  

The FBI seems to release a renewed warning about romance scams every Valentine’s Day when people are more likely to fall for a stranger online wanting to make a real connection and then eventually asking for money. I even found a podcast from the FBI in 2015 in which they warned that scammers “promise love, romance, to entice their victims online,” estimating that romance-related scams cost consumers $82 million in the last half of 2014.  

The main difference that I can tell between “pig butchering” and past romance scams is the sheer scale. Many actors running these operations are relying on human trafficking and sometimes literal imprisonment, forcing these people against their will to send these mass blocks of messages to a variety of targets indiscriminately. Oftentimes in these groups, scammers who are less “successful” in luring victims can be verbally and physically harassed and punished. That is, of course, a horrible human toll that these operations are taking, but they also extend far beyond the world of cybersecurity. 

In the case of pig butchering scams, it’s not really anything that can be solved by a cybersecurity solution or sold in a package. Instead, it relies on user education and the involvement of law enforcement agencies and international governments to ensure these farms can’t operate in the shows. The founders who run them are brought to justice. 

It’s never a bad thing that users become more educated on these scams, because of that, but I also feel it’s important to remember that romance-related scams, and really any social engineering built on a personal “relationship,” has been around for years, and “pig butchering” is not something new that just started popping up. 

These types of scams are ones that our culture has kind of just accepted as part of daily life at this point (who doesn’t get surprised when they get a call about their “car’s extended warranty?), and now the infrastructure to support these scams is taking a larger human toll than ever. 

**The one big thing **

Talos has yet another round of research into the Turla APT, and now we’re able to see the entire kill chain this actor uses, including the tactics, techniques and procedures (TTPs) utilized to steal valuable information from their victims and propagate through their infected enterprises. Before deploying TinyTurla-NG, Turla will attempt to configure anti-virus software exclusions to evade detection of their backdoor. Once exclsions have been set up, TTNG is written to the disk, and persistence is established by creating a malicious service. 

**Why do I care? **

Turla, and this recently discovered TinyTurlaNG tool that Talos has been writing about, is an international threat that’s been around for years, so it’s always important for the entire security community to know what they’re up to. Most recently, Turla used these tactics to target Polish non-governmental organizations (NGOs) and steal sensitive data.  

**So now what? **

During Talos’ research into TinyTurla-NG, we’ve released several new rounds of detection content for Cisco Secure products. Read our past two blog posts on this actor for more.  

**Top security headlines of the week **

**The Biden administration issued a renewed warning to public water systems and operators this week,** saying state-sponsored actors could carry out cyber attacks soon, citing ongoing threats from Iran and China. The White House and U.S. Environmental Protection Agency sent a letter to every U.S. governor this week warning them that cyber attacks could disrupt access to clean drinking water and “impose significant costs on affected communities.” The letter also points to the U.S. Cyber and Infrastructure Security Agency’s list of known exploited vulnerabilities catalog, asking the managers of public water systems to ensure their systems are patched against these vulnerabilities. The EPA pointed to Volt Typhoon, a recently discovered Chinese APT that has reportedly been hiding on critical infrastructure networks for an extended period. A meeting among federal government leaders from the EPA and other related agencies is scheduled for March 21 to discuss threats to public water systems and how they can strengthen their cybersecurity posture. (Bloomberg, The Verge) 

**UnitedHealth says it's still recovering from a cyber attack that’s halted crucial payments to health care providers across the U.S.,** but has started releasing some of those funds this week, and expects its payment processing software to be back online soon. The cyber attack, first disclosed in February, targeted Change Healthcare, a subsidiary of United, that handles payment processing and pharmaceutical orders for hospital chains and doctors offices. UnitedHealth’s CEO said in a statement this week that the company has paid $2 billion to affected providers who spent nearly a month unable to obtain those funds or needing to switch to a paper billing system. A recently published survey from the American Hospital Association found that 94 percent of hospitals that responded experienced financial disruptions from the Change Healthcare attack, and costs at one point were hitting $1 million in revenue per day. (ABC News, CNBC) 

**Nevada’s state court system is currently weighing a case that could undo end-to-end encryption across the U.S.** The state’s Attorney General is currently suing Meta, the creators of Facebook, Instagram and WhatsApp, asking the company to remove end-to-end encryption for minors on the platform, with the promise of being able to catch and charge users who abuse the platform to lure minors. However, privacy advocates are concerned that any rulings against Meta and its encryption policies could have larger ripple effects, and embolden others to challenge encryption in other states. Nevada is arguing that Meta’s Messenger a “preferred method” for individuals targeting Nevada children for illicit activities. Privacy experts are in favor of end-to-end encryption because it safeguards messages during transmission and makes it more difficult for other parties to intercept and read them — including law enforcement agencies. (Tech Policy Press, Bloomberg Law) 

**Can’t get enough Talos? **

*   The LockBit story: Why the ransomware affiliate model can turn takedowns into disruptions 
*   Cisco Closes $28B Splunk Deal: 5 Big AI, Security And Partner Things To Know 
*   Talos Takes Ep. #176: Why no one should be relying on passive security in 2024 
*   Dissecting a complex vulnerability and achieving arbitrary code execution in Ichitaro Word 
*   Netgear wireless router open to code execution after buffer overflow vulnerability 

**Upcoming events where you can find Talos **

**Botconf** **(April 23 - 26)** 

_Nice, Côte d'Azur, France_

> _This presentation from Chetan Raghuprasad details the Supershell C2 framework. Threat actors are using this framework massively and creating botnets with the Supershell implants._

**CARO Workshop 2024** **(May 1 - 3)** 

_Arlington, Virginia_

> Over the past year, we’ve observed a substantial uptick in attacks by YoroTrooper, a relatively nascent espionage-oriented threat actor operating against the Commonwealth of Independent Countries (CIS) since at least 2022. Asheer Malhotra's presentation at CARO 2024 will provide an overview of their various campaigns detailing the commodity and custom-built malware employed by the actor, their discovery and evolution in tactics. He will present a timeline of successful intrusions carried out by YoroTrooper targeting high-value individuals associated with CIS government agencies over the last two years.

**RSA** **(May 6 - 9)** 

_San Francisco, California_    

**Most prevalent malware files from Talos telemetry over the past week **

**SHA 256:** 0e2263d4f239a5c39960ffa6b6b688faa7fc3075e130fe0d4599d5b95ef20647   
**MD5:** bbcf7a68f4164a9f5f5cb2d9f30d9790   
**Typical Filename:** bbcf7a68f4164a9f5f5cb2d9f30d9790.vir   
**Claimed Product:** N/A   
**Detection Name:** Win.Dropper.Scar::1201 

**SHA 256:** 9f1f11a708d393e0a4109ae189bc64f1f3e312653dcf317a2bd406f18ffcc507    
**MD5:** 2915b3f8b703eb744fc54c81f4a9c67f    
**Typical Filename:** VID001.exe    
**Claimed Product:** N/A    
**Detection Name:** Win.Worm.Coinminer::1201 

**SHA 256:** a31f222fc283227f5e7988d1ad9c0aecd66d58bb7b4d8518ae23e110308dbf91    
**MD5:** 7bdbd180c081fa63ca94f9c22c457376   
**Typical Filename:** c0dwjdi6a.dll |  
**Claimed Product:** N/A    
**Detection Name:** Trojan.GenericKD.33515991 

**SHA 256:** 7b3ec2365a64d9a9b2452c22e82e6d6ce2bb6dbc06c6720951c9570a5cd46fe5   
**MD5:** ff1b6bb151cf9f671c929a4cbdb64d86   
**Typical Filename:** endpoint.query   
**Claimed Product:** Endpoint-Collector   
**Detection Name:** W32.File.MalParent 

**SHA 256:** e38c53aedf49017c47725e4912fc7560e1c8ece2633c05057b22fd4a8ed28eb3   
**MD5:** c16df0bfc6fda86dbfa8948a566d32c1   
**Typical Filename:** CEPlus.docm   
**Claimed Product:** N/A    
**Detection Name:** Doc.Downloader.Pwshell::mash.sr.sbx.vioc

“Pig butchering” is an evolution of a social engineering tactic we’ve seen for years

We now have new information on the entire kill chain this actor uses, including the tactics, techniques and procedures (TTPs) utilized to steal valuable information from their victims and propagate through their infected enterprises.

Cisco Talos is providing an update on its two recent reports on a new and ongoing campaign where Turla, a Russian espionage group, deployed their TinyTurla-NG (TTNG) implant. We now have new information on the entire kill chain this actor uses, including the tactics, techniques and procedures (TTPs) utilized to steal valuable information from their victims and propagate through their infected enterprises. 

*   Talos’ analysis, in coordination with CERT.NGO, reveals that Turla infected multiple systems in the compromised network of a European non-governmental organization (NGO). 

*   The attackers compromised the first system, established persistence and added exclusions to anti-virus products running on these endpoints as part of their preliminary post-compromise actions. 

*   Turla then opened additional channels of communication via Chisel for data exfiltration and to pivot to additional accessible systems in the network.

**Tracing Turla’s steps from compromise to exfiltration**

Talos discovered that post-compromise activity carried out by Turla in this intrusion isn’t restricted to the sole deployment of their backdoors. Before deploying TinyTurla-NG, Turla will attempt to configure anti-virus software exclusions to evade detection of their backdoor. Once exclusions have been set up, TTNG is written to the disk, and persistence is established by creating a malicious service.

**Preliminary post-compromise activity and TinyTurla-NG deployment**

After gaining initial access, Turla first adds exclusions in the anti-virus software, such as Microsoft Defender, to locations they will use to host the implant on the compromised systems.

ACTION

INTENT

HKLM\\SOFTWARE\\Microsoft\\Windows Defender\\Exclusions\\Paths | 

“C:\\Windows\\System32\\” = 0x0

\[T1562.001\] Impair Defenses: Disable or Modify Tools

Turla then sets up the persistence of the TinyTurla-NG implants using one or more batch (BAT) files. The batch files create a service on the system to persist the TTNG DLL on the system. 

ACTION

INTENT

reg add "HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Svchost" /v sysman /t REG\_MULTI\_SZ /d "sdm" /f

reg add "HKLM\\SYSTEM\\CurrentControlSet\\services\\sdm\\Parameters" /v ServiceDll /t REG\_EXPAND\_SZ /d "%systemroot%\\system32\\dcmd.dll" /f

\[T1543.003\] Create or Modify System Process: Windows Service

sc create sdm binPath= "c:\\windows\\system32\\svchost.exe -k sysman" type= share start= auto

sc config sdm DisplayName= "System Device Manager"

sc description sdm "Creates and manages system-mode driver processes. This service cannot be stopped."

  

\[T1543.003\] Create or Modify System Process: Windows Service

This technique is identical to that used by Turla in 2021 to achieve persistence for their TinyTurla implants. However, we’re still unsure why the actor uses two different batch files, but it seems to be an unnecessarily convoluted approach to evade detections.

In the case of TTNG, the service is created with the name “sdm” masquerading as a “System Device Manager” service. 

Batch file contents.

The creation and start of the malicious service kick starts the execution of the TinyTurla-NG implant via svchost\[.\]exe (Windows’ service container). TinyTurla-NG is instrumented further to conduct additional reconnaissance of directories of interest and then copy files to a temporary staging directory on the infected system, followed by subsequent exfiltration to the C2. TinyTurla-NG is also used to deploy a custom-built Chisel beacon from the open-sourced offensive framework.

**Custom Chisel usage**

On deployment, Chisel will set up a reverse proxy tunnel to an attacker-controlled box \[T1573.002 - Encrypted Channel: Asymmetric Cryptography\]. We’ve observed that the attackers leveraged the chisel connection to the initially compromised system, to pivot to other systems in the network. 

The presence of Windows Remote Management (WinRM)-based connections on the target systems indicates that chisel was likely used in conjunction with other tools, such as proxy chains and evil-winrm to establish remote sessions. WinRM is Microsoft’s implementation of the WS-Management protocol and allows Windows-based systems to exchange information and be administered using scripts or built-in utilities.

The overall infection chain is visualized below.

Turla tactics, tools and procedures flow.

Once the attackers have gained access to a new box, they will repeat their activities to create Microsoft Defender exclusions, drop the malware components, and create persistence, indicating that Turla follows a playbook that can be articulated as the following cyber kill chain.

Cyber kill chain.

Analyzing the traffic originating from Chisel revealed the tool beaconed back to its C2 server every hour.

While the infected systems were compromised as early as October 2023 and Chisel was deployed as late as December 2023, Turla operators conducted the majority of their data exfiltration over using Chisel much later on Jan. 12, 2024 \[T1041 - Exfiltration Over C2 Channel\].

**Coverage**

Ways our customers can detect and block this threat are listed below.

Cisco Secure Endpoint (formerly AMP for Endpoints) is ideally suited to prevent the execution of the malware detailed in this post. Try Secure Endpoint for free here.

Cisco Secure Web Appliance web scanning prevents access to malicious websites and detects malware used in these attacks.

Cisco Secure Email (formerly Cisco Email Security) can block malicious emails sent by threat actors as part of their campaign. You can try Secure Email for free here.

Cisco Secure Firewall (formerly Next-Generation Firewall and Firepower NGFW) appliances such as Threat Defense Virtual, Adaptive Security Appliance and Meraki MX can detect malicious activity associated with this threat.

Cisco Secure Malware Analytics (Threat Grid) identifies malicious binaries and builds protection into all Cisco Secure products.

Umbrella, Cisco's secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs and URLs, whether users are on or off the corporate network. Sign up for a free trial of Umbrella here.

Cisco Secure Web Appliance (formerly Web Security Appliance) automatically blocks potentially dangerous sites and tests suspicious sites before users access them.

Additional protections with context to your specific environment and threat data are available from the Firewall Management Center.

Cisco Duo provides multi-factor authentication for users to ensure only those authorized are accessing your network.

Open-source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org.

**IOCS****Hashes**

267071df79927abd1e57f57106924dd8a68e1c4ed74e7b69403cdcdf6e6a453b

d6ac21a409f35a80ba9ccfe58ae1ae32883e44ecc724e4ae8289e7465ab2cf40

ad4d196b3d85d982343f32d52bffc6ebfeec7bf30553fa441fd7c3ae495075fc

13c017cb706ef869c061078048e550dba1613c0f2e8f2e409d97a1c0d9949346

b376a3a6bae73840e70b2fa3df99d881def9250b42b6b8b0458d0445ddfbc044 

**Domains**

hanagram\[.\]jpthefinetreats\[.\]com

caduff-sa\[.\]chjeepcarlease\[.\]com

buy-new-car\[.\]com

carleasingguru\[.\]com

**IP Addresses**

91\[.\]193\[.\]18\[.\]120

New details on TinyTurla’s post-compromise activity reveal full kill chain

There is also a newly disclosed vulnerability in a graphics driver for some NVIDIA GPUs that could lead to a memory leak.

Wednesday, March 20, 2024 12:00

Cisco Talos’ Vulnerability Research team recently disclosed three vulnerabilities across a range of products, including one that could lead to remote code execution in a popular Netgear wireless router designed for home networks. 

There is also a newly disclosed vulnerability in a graphics driver for some NVIDIA GPUs that could lead to a memory leak. 

All the vulnerabilities mentioned in this blog post have been patched by their respective vendors, all in adherence to Cisco’s third-party vulnerability disclosure policy. 

For Snort coverage that can detect the exploitation of these vulnerabilities, download the latest rule sets from Snort.org, and our latest Vulnerability Advisories are always posted on Talos Intelligence’s website.  

**Netgear RAX30 JSON parsing stack-based buffer overflow vulnerability **

_Discovered by Michael Gentile._ 

The Netgear RAX30 wireless router contains a stack-based buffer overflow vulnerability that could allow an attacker to execute arbitrary code on the device.  

An adversary could send a targeted device a specially crafted HTTP request to eventually cause a buffer overflow condition. 

The RAX30 is a dual-band Wi-Fi router that’s commonly used on home networks. In an advisory about TALOS-2023-1887 (CVE-2023-48725), Netgear stated that the vulnerability “requires an attacker to have your WiFi password or an Ethernet connection to a device on your network to be exploited.” 

**NVIDIA D3D10 driver out-of-bounds read vulnerability **

_Discovered by Piotr Bania._ 

TALOS-2023-1849 (CVE-2024-0071) is an out-of-bounds read vulnerability in the shader functionality of the NVIDIA D3D10 driver that runs on several NVIDIA graphics cards. Drivers like D3D10 are usually necessary for the GPU to function properly. 

An adversary could send a specially crafted executable or shader file to the targeted machine to trigger an out-of-bounds read and eventually leak memory.  

This vulnerability could be triggered from guest machines running virtual environments to perform a guest-to-host escape. Theoretically, it could be exploited from a web browser, but Talos tested this vulnerability from a Windows Hyper-V guest using the RemoteFX feature, leading to execution of the vulnerable code on the Hyper-V host. While RemoteFX is no longer actively maintained by Microsoft, some older machines may still use this software.  

An out-of-bounds read vulnerability exists in the Shader functionality of NVIDIA D3D10 Driver, Version 546.01, 31.0.15.4601. A specially crafted executable/shader file can lead to an out-of-bounds read. An attacker can provide a specially crafted shader file to trigger this vulnerability. 

An adversary could also use this vulnerability to leak host data to the guest machine. 

**Denial-of-service vulnerability in Google Chrome Video Encoder **

_Discovered by Piotr Bania._ 

A denial-of-service vulnerability in Google Chrome’s video encoder could crash the browser.  

TALOS-2023-1870 is triggered if the targeted user visits an attacker-created website that contains specific code.  

Talos’ sample exploit runs a JavaScript code related to the Chrome video encoding functionality, eventually causing a denial-of-service in the browser and stopping all processes in Chrome.

Netgear wireless router open to code execution after buffer overflow vulnerability

Research conducted by Cisco Talos last year uncovered multiple vulnerabilities rated as low severity despite their ability to allow for full arbitrary code execution.

Dissecting a complex vulnerability and achieving arbitrary code execution in Ichitaro Word

Talos explores the recent law enforcement takedown of LockBit, a prolific ransomware group that claimed to resume their operations 7 days later.

Friday, March 15, 2024 10:00

In ancient Greek mythos, the mighty Hercules faced a seemingly insurmountable challenge when he encountered the Lernaean Hydra. This fearsome serpent had a terrifying ability: For every head that Hercules severed, two more would spring forth, creating a never-ending cycle of regrowth and renewal. 

Much like the Hydra, modern ransomware gangs present society with a daunting task. When law enforcement manages to take one adversary or low-level member off the streets, the victory is often short-lived. In the hidden depths of these criminal organizations, the heads — or leaders — remain shrouded in shadow, orchestrating their operations often with impunity. 

And so, as one member falls, two more may rise to take their place, perpetuating an enduring saga of illicit activity that are the challenges of our time: the ransomware ecosystem. A landscape where affiliates tend to move from ransomware group to ransomware group, following the money, bringing their skills and tools with them to conduct new attacks.

In this blog, we’ll explore the recent law enforcement takedown of LockBit, a group who previously held the title of the number one most deployed ransomware variant for two years running. Just seven days after the takedown, LockBit claimed to resume their operations.

**The History of LockBit**

LockBit emerged around 2019. Since then, it has continually evolved and innovated to update their ransomware and build their RaaS program.

For the past two years, LockBit ransomware operations accounted for over 25 percent of the total number of posts made to data leak sites. CISA’s assessment is also that LockBit has been the most deployed ransomware variant in recent years.

As we wrote in the 2023 Talos Year in Review report, posts made to the group’s data leak site ebbed and flowed from September 2022 to August 2023. Detections of LockBit activity appear to spike in March, partially coinciding with LockBit’s deployment against vulnerable instances of the printer management software PaperCut, where it has remained consistently high**.**

💡

In 2020, Talos researchers made contact with a self-described LockBit operator. Over several weeks, we conducted multiple interviews that gave us a rare, first-hand account of a ransomware operator’s cybercriminal activities. Confirmed theories included LockBit having a profit-sharing requirement that the affiliate has to meet for the first four or five ransoms. This also used to be the case for Maze. Also, keeping your word to the victim is an important part of LockBit’s business model. Read the interview in full __here__.

**The Collaboration Trend**

For the past two years, Talos researchers have written about a growing ransomware trend, wherein actors are increasingly collaborating with each other and sharing tools and infrastructure (aka the affiliate model).

For example, Talos recently reported on how the GhostSec and Stormous ransomware groups are jointly conducting double extortion ransomware attacks on various business verticals in multiple countries. The two groups have started a new ransomware-as-a-service (RaaS) program STMX\_GhostLocker, providing various options for their affiliates.

We are seeing more diversified groups employing multiple encryption programs, as well as less sophisticated actors “standing on the shoulders” of giants by using leaked ransomware code. Some players are exiting the game altogether, but not before selling their source code to the highest bidder. This is posing significant challenges to the security community, especially when it comes to attributing attacks.

In the case of LockBit, this was also a group that operated as a RaaS model. They recruited affiliates by offering them shares of profits and encouraging them to conduct ransomware attacks using LockBit’s tools and infrastructure. These affiliates were often unconnected, and as a result, there were many variations in the attacks that used LockBit ransomware.

Notably, the LockBit ransomware group posted on a Russian-speaking dark web forum in December 2023 offering to recruit ALPHV (BlackCat) and NoEscape ransomware affiliates and any of the ALPHV developers, after the Federal Bureau of Investigation (FBI)’s announcement of a disruption campaign against the ALPHV ransomware operation.

**Operation Cronos**

The NCA, working closely with the FBI and supported by international partners from nine other countries, covertly investigated LockBit as part of a dedicated taskforce called Operation Cronos. 

On Feb. 20, 2024, after infiltrating the group’s network, the NCA took control of LockBit’s primary administration environment. This environment enabled affiliates to build and carry out ransomware attacks, as well as host the group’s public-facing leak site on the dark web, which was used to threaten the publication of data stolen from victims. 

The technical infiltration and disruption were only the beginning of a series of actions against LockBit and their affiliates. In wider actions coordinated by Europol, at least three LockBit affiliates were arrested in Poland and Ukraine, and more than 200 cryptocurrency accounts linked to the group have been frozen.

**The Return**

Seven days after the operation, messages and leak information was published on a new LockBit page. Here are screenshots of their leak site taken daily from Feb. 27 – March 4, with a huge increase of cards on March 3.

The site lists both pre- and post-takedown victims, suggesting LockBit may not have lost access to their entire dataset or infrastructure. 

Of particular interest is the fbi.gov card in the lower right corner that links to a lengthy writeup (in English and Russian), stating what LockBit thinks happened during the operation. They talk about lessons learned, speculations and discredit the law enforcement agencies. Talos believes the operation was carried out by the NCA, not the FBI, as LockBit stated.

**A recurring theme**

While LockBit is currently dominating the headlines, we’ve seen similar stories before following takedown attempts. For example, the commodity trojan Trickbot had its infrastructure dismantled in February 2022.

However, Talos telemetry picked up Trickbot activity throughout 2023, as covered in our Year in Review.

**Still open for business**

Talos has intelligence that Lockbit is still accepting affiliates into their program. 

Does this mean that law enforcement operations are pointless? Far from it. Takedown attempts such as Operation Cronos severely disrupt their operations, and forces ransomware operators to change their attacks. The operation against LockBit doesn’t appear to have inflicted the final blow against the ransomware group, but it has wounded them. 

We also know that law enforcement was able to obtain troves of intelligence through their operation. That intelligence will only serve to be useful in further disruptions, undermining Lockbit's growth. Therefore, if you put Lockbit into a market perspective, they appear to be quite exposed. 

Crucially, as with the case of LockBit, decryption tools can be released so that victims of ransomware can gain access to their systems again. In January Talos obtained executable code capable of decrypting files affected by the Babuk Tortilla ransomware variant, allowing Talos to extract and share the private decryption key used by the threat actor.

Therefore, it’s important not to view this operation as a “one and done” effort. Sustained, targeted approaches from law enforcement and the defender community can and do have a significant impact. For example, following the FBI’s actions against BlackCat/ALPHV, the group reportedly denied an affiliate a $22 million ransomware payment before subsequently going out of business in early March, as Brian Krebs wrote about on his website a few days ago.

Azim Khodjibaev from Talos’ threat interdiction and intelligence organization team discusses the ebs and flows of ransomware groups after a takedown in the episode of Talos Takes below. This episode was recorded in 2022 after a separate law enforcement operation to disrupt LockBit.

**The lucrative affiliate model**

One of the major issues when tackling ransomware crime is the nature of the affiliate program, with actors often working for multiple RaaS outfits at a time. In underground forums, we are seeing increased advertisements by RaaS groups showcasing their affiliate programs and offering profit shares. They can offer large profits, as threat actors can conduct multiple campaigns using the encryption programs that are offered or distributed. 

In the case of the GhostSec group, they have a business model that offers affilates three different options: a paid version, a free version and a version that allows actors who don’t want to become a member ransomware gang but would like to publish victim data on their leak site.

We are also seeing multiple groups working together, sharing their malicious tooling with each other, then falling out, and then building trust back up with each other, adding to the difficulty in attributing attacks. Here are Talos’ Nick Biasini and Matt Olney talking about the impact of leaked ransomware code, where Matt describes the situation as “The Real Housewives of Eastern Europe:”

Fundamentally, ransomware continues to be hugely profitable and widespread. In the last quarter, the Talos Incident Response team responded to ransomware incidents involving Play, Cactus, BlackSuit and NoEscape ransomware for the first time, and there was a 17% rise in ransomware incidents in this quarter.

In the end, Operation Cronos may have disrupted LockBit’s operations temporarily with valuable assets gained, a weaker market position for the group, and a few affiliates are now sitting in jail. However, the Hyrdra’s roots run deeper, and this is why we may continue to see LockBit activity throughout the course of the year.

**Where to go from here**

Like Hercules who outwitted the Hydra with a blend of strength and strategy, our law enforcement’s relentless efforts are essential and commendable. It’s going to take persistent, strategic efforts to significantly damage RaaS operations and weaken the regenerative power of these gangs. Arrests at the top will be a key part of this. In the case of LockBit, it appears as though the leaders of the group have evaded arrest on this occasion.  

At the very same time the people of Lerna (or us, the private defenders), need to pay attention to the entire threat landscape. We can’t rely on just Hercules to take them down. Just like we can’t be sure there is just a single Hydra.

Read more about the recent ransomware operations Talos Incident Responders engaged in.

The LockBit story: Why the ransomware affiliate model can turn takedowns into disruptions

There are a few reasons why we’re so ready to jump to the “it’s a cyber attack!”

Thursday, March 14, 2024 14:00

Some of my Webex rooms recently have been blowing up with memes about blaming Canada or wild speculation that a state-sponsored actor is carrying out some sort of major campaign.  

After a widespread outage of cellular service with AT&T and other carriers a few weeks ago, people were sure it was some sort of coordinated attack to disrupt Americans’ services that largely power our day-to-day lives. The outage lasted about 11 hours, and after the fact, the company announced they’d give customers a whopping $5 credit to make up for the issue. The Federal Communications Commission also announced last week that it was launching a formal investigation into the outage, requesting more information about the exact cause and how many users were affected.  

About two weeks later, the same kinds of messages and questions to our team came flooding in when Meta experienced an outage across many of its platforms, most notably Facebook, Instagram and Threads. Though this only lasted a few hours, any time Americans can’t access their Instagram feeds, it’s going to make headlines. 

In both cases, consumers immediately wanted to start pointing fingers — Which actor was behind these? Why is there so little information about this outage? Is this China getting revenge for talk of forcing a TikTok sale? What’s the broader conspiracy behind this? The outages also quickly opened the door for some of the world’s chief spreaders of misinformation and fake news to start spreading conspiracy theories. 

The problem is, not every technical issue can or needs to be explained away by a cyber attack. That’s not to undersell the danger that state-sponsored APTs pose currently, or the fact that they \*could\* one day cause a disruption like this. But jumping to that conclusion every time Down Detector pops off is only going to spread fear/FUD and help these outlets for disinformation reach a larger audience.  

It creates a “boy who cried wolf” situation for when a major cyber attack actually does happen, and the average consumer is forced to make an immediate update to some piece of software or hardware. 

There are a few reasons why we’re so ready to jump to the “it’s a cyber attack!” conclusion. One is that Hollywood has been “glamorizing” the idea of a major cyber attack or major disruption for years now. Movies and TV shows like Netflix’s “Leave the World Behind” have dramatized what a major cyber attack or internet outage may look like, and how quickly it could lead to the unraveling of civilization. Because of our current doomscrolling culture, the second something even looks like it could be a cyber event, we’re ready to declare the end of our economy and society. 

It’s also sexier when it’s a cyber attack. AT&T says its outage was caused by a technical error that occurred when it was trying to upgrade its network’s capacity, explicitly stating it was not caused by any sort of disruption campaign or cyber attack. Meta simply chalked their outage up to a “technical issue.”  

None of these things make for good headlines. But sometimes, the simplest explanation is the most obvious one — we’ve all pressed a wrong button here or there, and stuff breaks on the internet all the time for all sorts of reasons. But “Users logged out of Instagram after Meta employee hits ‘enter’ too soon” isn’t as eye-catching as “Are Instagram and Facebook down because of a cyber attack?” 

Could these multi-billion-dollar corporations be lying? Sure, but I also find it hard enough to believe that the truth would not have made it out to consumers by now if these outages weren’t simple technical issues, nor would AT&T feel compelled to reimburse customers for something that could be totally out of their control. 

And if you ever get logged out of Facebook or Instagram, maybe you’re just better off being offline for a few hours anyway than immediately assuming Mahershala Ali is going to be knocking on your vacation home’s door in any minute.   

**The one big thing **

We want to keep reminding users to update and upgrade their network infrastructure. Aging devices like switches and routers that are used across the globe are a consistently vulnerable surface for adversaries to gain an initial foothold onto targeted networks. Talos recently highlighted the three most common post-compromise attacks that adversaries carry out after compromising these types of vulnerable devices, including modifying the device’s firmware and downgrading the firmware to remove older patches and open the door to new exploitable vulnerabilities. Nick Biasini from Talos Outreach also spoke about this issue for an article in NetworkWorld.  

**Why do I care? **

As Hazel Burton puts it in the blog post linked above: “Adversaries, particularly APTs, are capitalizing on this scenario to conduct hidden post-compromise activities once they have gained initial access to the network. The goal here is to give themselves a greater foothold, conceal their activities, and hunt for data and intelligence that can assist them with their espionage and/or disruptive goals. Think of it like a burglar breaking into a house via the water pipes. They’re not using “traditional” methods such as breaking down doors or windows (the noisy smash-and-grab approach) — they’re using an unusual route, because no one ever thinks their house will be broken into via the water pipes. Their goal is to remain stealthy on the inside while they take their time to find the most valuable artefacts.” 

**So now what? **

If you are using network infrastructure that is end of life, out of support, and now has vulnerabilities that cannot be patched, now really is the time to replace those devices. Using networking equipment that has been built with secure-by-design principles such as running secure boot, alongside having a robust configuration and patch management approach, is key to combatting these types of threats. Ensure that these devices are being watched very carefully for any configuration changes and patch them promptly whenever new vulnerabilities are discovered.   

**Top security headlines of the week **

**Security researchers have found a new vulnerability affecting chips made by nearly all major CPU makers dubbed “GhostRace.”** The vulnerability, identified as CVE-2024-2193, requires an adversary to win a race condition and to have physical or privileged access to the targeted machine. However, it could allow a malicious user to steal potentially sensitive information from memory like passwords and encryption keys. "The vulnerability affects many CPU architectures, including those made by Intel, AMD, Arm and IBM. It also affected some hypervisor vendors and the Linux operating system. AMD released an advisory this week that informed customers that they should follow previous defense guidance for other security flaws like Spectre that have affected CPUs in the past. “Our analysis shows all the other common write-side synchronization primitives in the Linux kernel are ultimately implemented through a conditional branch and are therefore vulnerable to speculative race conditions,” VU Amsterdam said in its blog post disclosing GhostRace. (SecurityWeek, Vrije Universiteit Amsterdam) 

**Health care providers are still reeling from a cyber attack on Change Healthcare**, a subsidiary of the United HealthGroup Inc. insurance provider. First Health Advisory, a digital health risk assurance firm, recently estimated that health care providers are losing an estimated $100 million daily as they still cannot process payments from insurance providers. Change first disclosed the suspected ransomware attack in late February, and on March 5, the U.S. government announced a plan to provide relief payments for providers who are facing financial shortfalls due to the outage. Many doctors' offices and care clinics are facing late rent payments and unpaid invoices. The attack has also limited some patients’ ability to obtain pre-authorization for certain services and surgeries, and others have not been able to refill their prescriptions at hospitals. U.S. Congress is also asking the CEO of United HealthGroup to appear before a committee to answer questions about the hack. (CBS News, Bloomberg) 

**The U.S. has placed formal sanctions against two individuals and five entities associated with the Intellexa Consortium,** responsible for developing and distributing the Predator spyware. Talos has previously reported on Intellexa’s tools, and how their spyware is silently loaded onto targeted devices. This is the first time the Treasury Department has sanctioned a spyware organization and announced it publicly. The sanctions include five vendors who work with Intellexa to sell the spyware, all of whom are spread across Europe. Intellexa itself is based in Greece. Predator and other spyware developed by private parties are often used to target high-risk individuals to track their communication and movement, including politicians, journalists, activists and political dissidents. Under the sanctions, anyone in the U.S. is forbidden from doing business with Intellexa or the associated companies and individuals. The Biden administration has long pushed for additional action against spyware makers, including Israel-based NSO Group, which distributes the Pegasus spyware. (Voice of America, Axios) 

**Can’t get enough Talos? **

*   Threat actors leverage document publishing sites for ongoing credential and session token theft 
*   Heather Couk is here to keep your spirits up during a cyber emergency, even if it takes the “Rocky” music 
*   Another Patch Tuesday with no zero-days, only two critical vulnerabilities disclosed by Microsoft 
*   Talos Takes Ep. #175: What's new about GhostSec's ransomware-as-a-service model 

**Upcoming events where you can find Talos **

**Botconf** **(April 23 - 26)** 

_Nice, Côte d'Azur, France_

> _This presentation from Chetan Raghuprasad details the Supershell C2 framework. Threat actors are using this framework massively and creating botnets with the Supershell implants._

**CARO Workshop 2024** **(May 1 - 3)** 

_Arlington, Virginia_

> Over the past year, we’ve observed a substantial uptick in attacks by YoroTrooper, a relatively nascent espionage-oriented threat actor operating against the Commonwealth of Independent Countries (CIS) since at least 2022. Asheer Malhotra's presentation at CARO 2024 will provide an overview of their various campaigns detailing the commodity and custom-built malware employed by the actor, their discovery and evolution in tactics. He will present a timeline of successful intrusions carried out by YoroTrooper targeting high-value individuals associated with CIS government agencies over the last two years.

**RSA** **(May 6 - 9)** 

_San Francisco, California_   

**Most prevalent malware files from Talos telemetry over the past week **

**SHA 256:** a31f222fc283227f5e7988d1ad9c0aecd66d58bb7b4d8518ae23e110308dbf91    
**MD5:** 7bdbd180c081fa63ca94f9c22c457376   
**Typical Filename:** c0dwjdi6a.dll   
**Claimed Product:** N/A    
**Detection Name:** Trojan.GenericKD.33515991 

**SHA 256:** 24283c2eda68c559f85db7bf7ccfe3f81e2c7dfc98a304b2056f1a7c053594fe   
**MD5:** 49ae44d48c8ff0ee1b23a310cb2ecf5a   
**Typical Filename:** nYzVlQyRnQmDcXk   
**Claimed Product:** N/A   
**Detection Name:** Win.Dropper.Scar::tpd 

**SHA 256:** e38c53aedf49017c47725e4912fc7560e1c8ece2633c05057b22fd4a8ed28eb3   
**MD5:** c16df0bfc6fda86dbfa8948a566d32c1   
**Typical Filename:** CEPlus.docm   
**Claimed Product:** N/A    
**Detection Name:** Doc.Downloader.Pwshell::mash.sr.sbx.vioc 

**SHA 256:** 9f1f11a708d393e0a4109ae189bc64f1f3e312653dcf317a2bd406f18ffcc507    
**MD5:** 2915b3f8b703eb744fc54c81f4a9c67f    
**Typical Filename:** VID001.exe    
**Claimed Product:** N/A    
**Detection Name:** Win.Worm.Coinminer::1201 

**SHA 256:** e4973db44081591e9bff5117946defbef6041397e56164f485cf8ec57b1d8934   
**MD5:** 93fefc3e88ffb78abb36365fa5cf857c   
**Typical Filename:** Wextract   
**Claimed Product:** Internet Explorer   
**Detection Name:** W32.File.MalParent

Not everything has to be a massive, global cyber attack

Talos IR has responded to several recent incidents in which threat actors used legitimate digital document publishing sites such as Publuu and Marq to host phishing documents as part of ongoing credential and session harvesting attacks.

Wednesday, March 13, 2024 08:00

*   Cisco Talos Incident Response (Talos IR) has observed the ongoing use of legitimate digital document publishing (DDP) sites for phishing, credential theft and session token theft during recent incident response and threat intelligence engagements.
*   Hosting phishing lures on DDP sites increases the likelihood of a successful phishing attack, since these sites often have a favorable reputation, are unlikely to appear on web filter blocklists, and may instill a false sense of security in users who recognize them as familiar or legitimate.
*   DDP sites allow adversaries to quickly deploy and decommission malicious documents on a single platform. Talos IR also observed an adversary move between DDP sites within a short period.

Talos IR has responded to several recent incidents in which threat actors used legitimate digital document publishing sites such as Publuu and Marq to host phishing documents as part of ongoing credential and session harvesting attacks. Threat actors have used a similar tactic of deploying phishing lures on well-known cloud storage and contract management sites such as Google Drive, OneDrive, SharePoint, DocuSign and Oneflow. However, DDP sites could represent a blind spot for defenders, because they are unfamiliar to trained users and unlikely to be flagged by email and web content filtering controls. Recent malicious activity observed across these platforms underscores the need for security teams to ensure that phishing protections and user awareness training programs consider these and similar sites.

**Background and observations**

 “Digital Document Publishing sites” refers to websites that allow users to upload and share PDF files in a browser-based flipbook format. Visitors can view an entire PDF by flipping from page to page without downloading the document, and some DDP sites offer features that allow other types of interaction with the document. Examples of DDP sites include Publuu, Marq, FlipSnack, Issuu, FlippingBook, RelayTo and SimpleBooklet.

The sites discussed in this blog are not malicious. Rather, they are being abused by threat actors.

**Delivery mechanism**

Threat actors integrate DDP sites as a secondary or intermediate stage of the attack chain, which follows tried-and-true phishing methods.

*   The victim receives an email containing a link to a document hosted on a legitimate DDP site. The email’s subject and/or body often includes the phrase “New Document from \[sender organization\],” and leaves the “To” header blank. Instead, the actors load the target list into the “BCC” field.
*   The DDP-hosted document includes a link to an external, adversary-controlled site.
*   When clicked, the link either moves the victim directly to the adversary-controlled site, or through a series of redirects. Talos IR also observed the inclusion of Cloudflare CAPTCHAs as part of some redirects, an adversary technique reported by Cofense, Netskope and other security teams over the past six months.
*   The victim arrives at the adversary-controlled site, which mimics a legitimate authentication page and is designed to capture user credentials or session tokens during authentication.

Attacks leveraging DDP sites for credential and session token theft often take place through unauthorized access to another legitimate email inbox. In a sort of “cascading” business email compromise (BEC) process, the threat actor creates infrastructure and phishing lures to target a specific victim, then leverages that victim’s established connections to conduct follow-on attacks against other organizations. A portion of the infrastructure created for the original target may be reused, while other portions are recreated to increase the likelihood of success during the subsequent attacks. 

**Lure customization**

DDP sites offer custom capabilities that lend credence to a phishing attack. Not only can the threat actor customize the uploaded phishing document, the web page hosting that document can also be modified. Page customization options include changing the background, banner, border or HTML Title tag. These quick configurations create more convincing lures and are likely to garner a higher click-through rate to the credential harvesting page. 

DDP-hosted lure customization observed during investigation ranged from pages listing the organization name only in the HTML Title tag, to a highly customized lure and landing page combination targeting users of a Canadian telecom provider. In the latter case, the final credential harvesting page was a near replica of the provider’s legitimate user login page, though it was hosted on an unrelated webwave\[.\]dev subdomain. 

**Historical trends**

Expanding the scope of the investigation to include historical data reveals a possible trend where threat actors migrate between DDP sites or rapidly activate and deactivate similar campaigns on the same site over time. For example, Talos IR observed a cluster of activity on SimpleBooklet from late October to early November 2020, and another on RelayTo in early September 2023. More recently, an adversary was observed operating the same credential-harvesting attack, first on Publuu, then later Issuu. 

**Adversary advantages create challenges for defenders**

DDP sites create advantages for threat actors seeking to thwart contemporary phishing protections. The same features and benefits that attract legitimate users to these sites can be abused by threat actors to increase the efficacy of a phishing attack. Given some of these advantages, threat actors may find DDP sites as useful as creating spoofed domains or compromising legitimate sites for phishing and credential theft.

**DDP sites offer low-cost, transient file hosting**

Many DDP sites offer either a free tier or a no-cost trial period where a defined number of files can be published for a limited time. No-cost trial periods usually require only limited personal identifiers and no payment methods. Threat actors can quickly and easily create multiple free accounts, with a varying number of malicious pages per account.

Some DDP sites also allow a link expiration to be set for published content. This feature creates a “set it and forget it” capability for threat actors, who are no longer required to closely track where phishing documents have been deployed so they can be decommissioned. Instead, a link expiration date and time is configured during page creation, ensuring the content will be rendered unavailable automatically, usually after only a short time.

Talos IR observed instances where an adversary launched, then disabled a DDP page in fewer than 24 hours, and others where the DDP page was left active but the final landing page on the adversary-controlled domain was removed through DNS fast fluxing or another mechanism.

This transient nature of DDP pages creates challenges for security teams and complicates the incident response process. While it’s possible to detect, create internal alerts for, and/or notify security personnel about a DDP-hosted lure, the brief availability of the pages creates a compressed response time for defenders. Understanding the theme of the lure, the associated adversary-controlled domains, and the intent of the attack in such a short time may be difficult, even for experienced security teams.

**DDP sites usually have a favorable web reputation.**

The ratio of legitimate to compromised pages hosted on DDP sites is likely quite low. While that ratio seemed to vary by DDP provider, Talos IR found that most pages created recently across all DDP sites hosted legitimate content. Unless this trend continues to shift toward hosting greater volumes of malicious content, these sites will maintain a favorable reputation score and are less likely to be included in automated blocklists. 

A favorable web reputation score may also mislead users who investigate the DDP site using popular open-source intelligence tools or a basic internet search, leading to higher click and credential capture rates than sites with an unknown or poor reputation.

**Site**

**Domain Registration**

**Umbrella Unique Visitors Score\***

**Umbrella Reputation Score\*\***

**Publuu**

2019-02-28 (IS)

63

53 (Medium Risk)

**Marq**

2004-06-19 (IS)

76

9 (Low Risk)

**FlipSnack**

2010-06-03 (US)

96

11 (Low Risk)

**Issuu**

2007-04-19 (GB)

100

9 (Low Risk)

**RelayTo**

2013-12-02 (US)

53

58 (Medium Risk)

_\* Umbrella’s Unique Visitors Score is included to illustrate estimated traffic volume per site as of Feb. 2, 2024._

_\*\* Reputation Score as of Feb. 2, 2024._

**DDP productivity features may inhibit malicious link detection.**

Talos IR found that productivity features on at least one DDP site inhibited traditional methods of extracting the true URL from a phishing link. During the investigation of a malicious document hosted on Publuu, a custom sub-menu was displayed when the user right-clicked on the URL. While this sub-menu included options that would benefit legitimate users, it did not provide a clear option to copy the URL behind the “View Online PDF” hyperlink. Further, no tooltip popups appeared to show the URL when hovering over the link. 

**Case studies**

Two recent Talos IR engagements involved the use of a DDP site as part of potential credential and session token-harvesting attacks.

**Publuu**

Several individuals at the targeted organization received phishing emails from a compromised email address belonging to a trusted third-party vendor with the subject, “New Document from \[third-party vendor\]”.

The link included in the body of the email led to a Publuu flipbook, with a URL like https://publuu[.]com/flip-book/[6_digit_identifier]/[6_digit_identifier]. The phishing document was a generic, widely used file observed in similar attacks on other DDP sites. However, while the phishing document was reused, the adversary had modified the Publuu page with the sender organization’s name to lend authenticity to the document.

Clicking the “VIEW ONLINE PDF” link directed the user to a Cloudflare CAPTCHA, a technique described in the publications by Cofense and Netskope linked above. Use of the CAPTCHA likely has a dual purpose, as it both protects the credential harvesting page from automated access while giving the impression of a legitimate site to users who fall victim to the phishing link.

After completing the CAPTCHA, the victim is directed to a convincing replica of a Microsoft 365 authentication page. The URL for the page contains a lengthy alphanumeric string, which may act as an identifier for the visitor. The adversary-controlled domain associated with the authentication page was atlas-aerspace[.]onlineextracted. The customization of the original Publuu page to the target organization in contrast to this unrelated spoofed domain suggests this incident may have been part of a cascading BEC attack.  

Talos IR later identified an attack chain hosted on the Issuu DDP site with similar indicators. The phishing document was nearly identical, though, unlike the Publuu link, this link URL leveraged the Google AMP to Cloudflare CAPTCHA flow described in the Cofense blog. The credential harvest page was ultimately located at the domain aerospace-atlas[.]online and included the same identifier-style URL string as the one observed with the atlas-aerspace[.]online90 days domain.

In aggregate, the following similar domains – all hosted by Cloudflare – were registered within 90 days. The first two domains were found to be associated with phishing lures hosted on DDP sites, suggesting an effort to target users of the legitimate atlas-aerospace[.]com domain.

*   aerospace-atlas[.]online (registered Jan. 24, 2024)
*   atlas-aerspace[.]online (registered Dec. 19, 2023)
*   atlas-aerspace[.]com (registered Oct. 25, 2023)

Talos provided notification through established channels so affected organizations could review and address this activity.

**Marq**

Talos IR also responded to an incident involving the Marq DDP site. The Marq page hosting the phishing document had already been deactivated, but Talos IR used other forensic data to determine the URL of the associated credential harvesting page. The first part of that URL was https[:]//mvnwsenterprise[.]top:443/aadcdn.msauth.net/.

While the Marq page could not be accessed, Talos IR identified similar pages through open- and closed-source intelligence. These pages were customized to show the sender organization in the HTML Title tag (displayed in the browser tab) but otherwise used an identical “Microsoft365 Online Fax” lure. Unlike some activity clusters on other DDP sites, each page was configured with a unique URL using the .top top-level domain, such as onedrivesmncs[.]top, onedrivemwsamc[.]top, and 347nsm239mws934[.]top. Another common characteristic was the presence of the URL query string tkmilric in all URLs embedded in the phishing document. 

Once clicked, the link passed the user to the spoofed Microsoft authentication page, which resided at the redirect.cgi path of the unique \`.top\` domain. The URL query string for this page included a “ref” parameter, which contained a Base64 and URL encoded value. An example of the decoded value is:

https://login.microsoftonline.com/common/oauth2/authorize?client_id=00000002-0000-0ff1-ce00-000000000000&redirect_uri=https://outlook.office.com/owa/&resource=00000002-0000-0ff1-ce00-000000000000&response_mode=form_post&response_type=code id_token&scope=openid&msafed=1&msaredir=1&client-request-id=**[REDACTED]**&protectedtoken=true&claims={"id_token":{"xms_cc":{"values":["CP1"]}}}&nonce=**[REDACTED]**&state=**[REDACTED]**

The value 00000002-0000-0ff1-ce00-000000000000 found in the client_id and resource parameters is the Microsoft Application ID for Office 365 Exchange Online. The claims string {"id_token":{"xms_cc":{"values":["CP1"]}}} is a required component for a client application to communicate its capabilities to Microsoft Entra ID in an OAuth 2.0 authorization flow. These characteristics likely indicate a campaign to capture session tokens for Microsoft 365 components using the same lure and customized or DGA-generated domains.

**Other DDP Sites**

Following these investigations, Talos IR identified similar activity on other DDP sites. The following examples are provided to demonstrate similarities across DDP sites and are not related to any ongoing or prior Talos IR investigations.

**Flipsnack**

Talos IR identified at least two lure formats used recently on FlipSnack – one eFax PDF-themed lure, and one SharePoint PDF-themed lure. Both landing pages had been removed by the adversary at the time of Talos IR’s review, but the URL for the adversary-controlled page associated with the SharePoint lure (afurrytailwedding[.]com/cure/MSthOffice/index.phpexcept) could indicate a potential Microsoft 365 credential harvesting effort. Neither lure had been customized to target a specific victim. 

**Issuu**

Malicious documents found on Issuu were very similar to those observed on Publuu, except for minor details like a “Reference” number and the link URL. Of the two links tested by Talos IR, one was redirected through an intermediary site before reaching the landing page. The other leveraged the Google AMP and Cloudflare CAPTCHA flow reported by Cofense. Again, the landing pages for both examples had been removed by the adversary at the time of Talos IR’s review.

**RelayTo**

Talos IR located at least two different phishing lures that had been deployed to the RelayTo site in early September 2023. One of these lures was published repeatedly from multiple RelayTo accounts with modifications to only the name of the associated organization. The link in each lure – https[:]//secure-docsx[.]com/efgh5678 – was the same. The secure-docsx[.]combefore the domain had been registered a week this activity began and was followed by the creation of the secure-docu[.]com domain, with which it shared registrant details.

**SimpleBooklet**

Talos IR could not locate a malicious page on the SimpleBooklet site that had not already been deactivated. However, a review of related URLs in VirusTotal suggests that an adversary made prolific use of this site for phishing and possible credential theft from October 2020 through January 2021.

**Defender actions**

Defenders should consider the following actions to help defend against phishing attacks that leverage DDP sites.

*   Block common DDP sites via border security devices, endpoint detection and response (EDR) like Cisco Secure Endpoint, web content filtering, and/or DNS security controls if access to these sites is not required for normal business operations. If blocking these sites will disrupt normal operations, develop a procedure to ensure malicious domains identified in DDP-hosted phishing lures can be quickly blocked.
*   Configure email security controls to detect and alert on links in emails containing common DDP site URLs.
*   Leverage threat intelligence to quickly identify newly created sites related to known threats – in this case, new DDP sites that may be leveraged by threat actors.
*   Monitor for behavioral trends within the organization’s internal environment that could indicate coordinated malicious activity, including activity to blocked sites.
*   Update user security awareness training to include information about DDP sites and other cloud-hosted phishing attack methods. Reinforce a “see something, say something” mentality when users are uncertain about a site’s legitimacy.

End users can also support defenders by remaining vigilant for documents shared over unusual or uncommon sites, even if those sites are legitimate and have a favorable reputation, and by following their organization’s guidelines for reporting suspicious emails.

Threat actors leverage document publishing sites for ongoing credential and session token theft

March’s Patch Tuesday is relatively light, containing 60 vulnerabilities — only two labeled “critical.”

Tuesday, March 12, 2024 14:07

For the second month in 2024, there are no actively exploited vulnerabilities included in this month’s security update from Microsoft. 

March’s Patch Tuesday is relatively light, containing 60 vulnerabilities — only two labeled “critical.” Last month’s Patch Tuesday included more than 70 security vulnerabilities affecting Microsoft products, and there were even fewer in January and December, especially when compared to 2023.  

Still, both critical vulnerabilities addressed this month are notable because they affect Windows Hyper-V, potentially allowing an adversary to target a host machine from a virtual machine environment.   

All other vulnerabilities Microsoft disclosed Tuesday are considered to be of “important” severity.  

CVE-2024-21408 is a denial-of-service vulnerability in Windows Hyper-V that could allow an adversary to target a host machine from inside a VM. However, Microsoft did not provide any additional details on how this denial-of-service could occur, and despite being listed as critical, it only scored a 5.5 out of 10 in the CVSS severity scoring system.   

The other critical issue is CVE-2024-21407, a remote code execution also in Hyper-V. An attacker inside a VM environment could remotely execute code on the host machine by sending specially crafted file operation requests to hardware resources on the VM. However, the adversary would need to be authenticated inside the VM first and acquire certain, specific information about the environment to be gathered before a successful attack. 

Another remote code execution vulnerability — of which there are 19 in Tuesday’s release, CVE-2024-21334, exists in Open Management Infrastructure. A remote, unauthenticated attacker could exploit this vulnerability by accessing the OMI instance from the internet and sending specially crafted requests to trigger a use-after-free vulnerability.  

CVE-2024-21334 is only considered by Microsoft to be “important,” though it has a CVSS score of 9.8 out of 10 — the highest of any vulnerability disclosed as part of March’s Patch Tuesday that affects a Microsoft product.  

A complete list of all the other vulnerabilities Microsoft disclosed this month is available on its update page. 

In response to these vulnerability disclosures, Talos is releasing a new Snort rule set that detects attempts to exploit some of them. Please note that additional rules may be released at a future date and current rules are subject to change pending additional information. Cisco Security Firewall customers should use the latest update to their ruleset by updating their SRU. Open-source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org. 

The rules included in this release that protect against the exploitation of many of these vulnerabilities are 63140, 63141, 63142, 63144, 63145, 63152, 63153, 63155, 63156, 63161, 63162 and 63169 - 63170. There are also Snort 3 rules 300855, 300856 and 300858 - 300860.

Source

TALOS