Headline
Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server
Summary Microsoft is investigating two reported zero-day vulnerabilities affecting Microsoft Exchange Server 2013, 2016, and 2019. The first vulnerability, identified as CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability, while the second, identified as CVE-2022-41082, allows remote code execution (RCE) when PowerShell is accessible to the attacker. At this time, Microsoft is aware of limited … Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server Read More »
Summary
Microsoft is investigating two reported zero-day vulnerabilities affecting Microsoft Exchange Server 2013, 2016, and 2019. The first vulnerability, identified as CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability, while the second, identified as CVE-2022-41082, allows remote code execution (RCE) when PowerShell is accessible to the attacker.
At this time, Microsoft is aware of limited targeted attacks using the two vulnerabilities to get into users’ systems. In these attacks, CVE-2022-41040 can enable an authenticated attacker to remotely trigger CVE-2022-41082. It should be noted that authenticated access to the vulnerable Exchange Server is necessary to successfully exploit either of the two vulnerabilities.
We are working on an accelerated timeline to release a fix. Until then, we’re providing the mitigations and detections guidance below to help customers protect themselves from these attacks.
Microsoft Exchange Online has detections and mitigation in place to protect customers. Microsoft is also monitoring these already deployed detections for malicious activity and will take necessary response actions to protect customers.
We will continue to provide updates here to help keep customers informed.
Mitigations
Microsoft Exchange Online Customers do not need to take any action. On premises Microsoft Exchange customers should review and apply the following URL Rewrite Instructions and block exposed Remote PowerShell ports.
The current mitigation is to add a blocking rule in “IIS Manager -> Default Web Site -> Autodiscover -> URL Rewrite -> Actions” to block the known attack patterns.
Microsoft has confirmed that the following URL Rewrite Instructions, which are currently being discussed publicly, are successful in breaking current attack chains.
Open the IIS Manager.
Expand the Default Web Site.
Select Autodiscover.
In the Feature View, click URL Rewrite.
In the Actions pane on the right-hand side, click Add Rules.
Select Request Blocking and click OK.
Add String “.*autodiscover\.json.*\@.*Powershell.*” (excluding quotes) and click OK.
Expand the rule and select the rule with the Pattern “.*autodiscover\.json.*\@.*Powershell.*” and click Edit under Conditions.
Change the condition input from {URL} to {REQUEST_URI}
Impact: There is no known impact to Exchange functionality if the URL Rewrite module is installed as recommended.
Authenticated attackers who can access PowerShell Remoting on vulnerable Exchange systems will be able to trigger RCE using CVE-2022-41082. Blocking the ports used for Remote PowerShell can limit these attacks.
- HTTP: 5985
- HTTPS: 5986
Detections
Microsoft Sentinel
While we do not currently have a specific detection query for this issue, based on what we are seeing in the wild, these techniques will help defenders. Our post on Web Shell Threat Hunting with Microsoft Sentinel also provides valid guidance for looking for web shells in general.
The Exchange SSRF Autodiscover ProxyShell detection, which was created in response to ProxyShell, can be used for queries as there are similarities in function with this threat. Also, we have a new Exchange Server Suspicious File Downloads query which specifically looks for suspicious downloads in IIS logs. In addition to those, we have a few more that could be helpful in looking for post-exploitation activity:
- Exchange OAB Virtual Directory Attribute Containing Potential Webshell
- Web Shell Activity
- Malicious web application requests linked with Microsoft Defender for Endpoint alerts
- exchange-iis-worker-dropping-webshell
- Web shell Detection
Microsoft Defender for Endpoint
Microsoft Defender for Endpoint detects post-exploitation activity. The following alerts can be related to this threat:
- Possible web shell installation
- Possible IIS web shell
- Suspicious Exchange Process Execution
- Possible exploitation of Exchange Server vulnerabilities
- Suspicious processes indicative of a web shell
- Possible IIS compromise
Defender for Endpoint customers with Microsoft Defender Antivirus enabled can also detect the web shell malware used in in-the-wild exploitation of this vulnerability as of this writing with the following alerts:
- ‘Chopper’ malware was detected on an IIS Web server
- ‘Chopper’ high-severity malware was detected
Microsoft Defender Antivirus
Microsoft Defender Antivirus detects the post exploitation malware used in current in-the-wild exploitation of this vulnerability as the following:
- Backdoor:ASP/Webshell.Y (Backdoor:ASP/Webshell.Y threat description – Microsoft Security Intelligence)
- Backdoor:Win32/RewriteHttp.A (Backdoor:Win32/RewriteHttp.A threat description – Microsoft Security Intelligence)
Related news
Cloud services provider Rackspace on Thursday confirmed that the ransomware gang known as Play was responsible for last month's breach. The security incident, which took place on December 2, 2022, leveraged a previously unknown security exploit to gain initial access to the Rackspace Hosted Exchange email environment. "This zero-day exploit is associated with CVE-2022-41080," the Texas-based
The Play ransomware group was spotted exploiting another little-known SSRF bug to trigger RCE on affected Exchange servers.
Categories: News Categories: Ransomware Tags: Rackspace Tags: Exchange Tags: ransomware Tags: ProxyNotShell Rackspace said a ransomware incident affected its Hosted Exchange environment and caused service disruptions. (Read more...) The post Rackspace confirms it suffered a ransomware attack appeared first on Malwarebytes Labs.
This Metasploit module chains two vulnerabilities on Microsoft Exchange Server that, when combined, allow an authenticated attacker to interact with the Exchange Powershell backend (CVE-2022-41040), where a deserialization flaw can be leveraged to obtain code execution (CVE-2022-41082). This exploit only supports Exchange Server 2019. These vulnerabilities were patched in November 2022.
Let's face it: Having “2022 election” in the headline above is probably the only reason anyone might read this story today. Still, while most of us here in the United States are anxiously awaiting the results of how well we've patched our Democracy, it seems fitting that Microsoft Corp. today released gobs of security patches for its ubiquitous Windows operating systems. November's patch batch includes fixes for a whopping six zero-day security vulnerabilities that miscreants and malware are already exploiting in the wild.
Long-awaited security fixes for ProxyNotShell and Mark of the Web bypasses are part of a glut of actively exploited zero-day vulnerabilities and other critical flaws that admins need to prioritize in the coming hours.
Hello everyone! This episode will be about Microsoft Patch Tuesday for October 2022, including vulnerabilities that were added between September and October Patch Tuesdays. As usual, I use my open source Vulristics project to create the report. All vulnerabilities: 105Urgent: 2Critical: 1High: 29Medium: 71Low: 2 Let’s take a look at the most interesting vulnerabilities: Two […]
Categories: Exploits and vulnerabilities Categories: News Tags: Microsoft Tags: Apple Tags: Google Tags: Android Tags: Samsung Tags: Xiaomi Tags: Adobe Tags: SAP Tags: VMWare Tags: Fortinet Tags: CVE-2022-41033 Tags: CVE-2022-41040 Tags: zero-day No fix for ProxyNotShell (Read more...) The post Update now! October patch Tuesday fixes actively used zero-day...but not the one you expected appeared first on Malwarebytes Labs.
The computing giant didn't fix ProxyNotLogon in October's Patch Tuesday, but it disclosed a rare 10-out-of-10 bug and patched two other zero-days, including one being exploited.
Microsoft on Friday disclosed it has made more improvements to the mitigation method offered as a means to prevent exploitation attempts against the newly disclosed unpatched security flaws in Exchange Server. To that end, the tech giant has revised the blocking rule in IIS Manager from ".*autodiscover\.json.*Powershell.*" to "(?=.*autodiscover\.json)(?=.*powershell)." The list of
By Jon Munshaw. Welcome to this week’s edition of the Threat Source newsletter. As I wrote about last week, I’ve been diving a lot into apps’ privacy policies recently. And I was recently made aware of a new type of app I never knew existed — family trackers. There are countless mobile apps for parents to track their children or other family members based on their location, phone usage, and even driving speed. As an anxious soon-to-be-parent, this sounds intriguing to me — it’d be a supped-up version of Find my Friends on Apple devices so I’d never have to ask my teenager (granted, I’m many years away from being at that stage of my life) when they were coming home or where they were. Just as with all other types of mobile apps, there are pitfalls, though. Life360, one of the most popular of these types of apps and even tells users what their maximum driving speed was on a given trip, was found in December 2021 to be selling precise location data on its users, potentia...
Microsoft has revised its mitigation measures for the newly disclosed and actively exploited zero-day flaws in Exchange Server after it was found that they could be trivially bypassed. The two vulnerabilities, tracked as CVE-2022-41040 and CVE-2022-41082, have been codenamed ProxyNotShell due to similarities to another set of flaws called ProxyShell, which the tech giant resolved last year.
Nicknamed ProxyNotShell, a new exploit used in the wild takes advantage of the recently published Microsoft Server-Side Request Forgery (SSRF) vulnerability CVE-2022-41040 and a second vulnerability, CVE-2022-41082 that allows Remote Code Execution (RCE) when PowerShell is available to unidentified attackers. Based on ProxyShell, this new zero-day abuse risk leverage a chained attack similar to
‘ProxyNotShell’ abuse less severe than 2021 attack wave due to authentication requirement
Microsoft Exchange Server Elevation of Privilege Vulnerability.
Microsoft Exchange Server Remote Code Execution Vulnerability.
Microsoft on Friday disclosed that a single activity group in August 2022 achieved initial access and breached Exchange servers by chaining the two newly disclosed zero-day flaws in a limited set of attacks aimed at less than 10 organizations globally. "These attacks installed the Chopper web shell to facilitate hands-on-keyboard access, which the attackers used to perform Active Directory
While organizations wait for an official patch for the two zero-day flaws in Microsoft Exchange, they should scan their networks for signs of exploitation and apply these mitigations.
Cisco Talos has released new coverage to detect and prevent the exploitation of two recently disclosed vulnerabilities collectively referred to as "ProxyNotShell," affecting Microsoft Exchange Servers 2013, 2016 and 2019. One of these vulnerabilities could allow an attacker to execute remote code on the targeted server. Limited exploitation of these vulnerabilities in the wild has been reported. CVE-2022-41040 is a Server Side Request Forgery (SSRF) vulnerability, while CVE-2022-41082 enables Remote Code Execution (RCE) when PowerShell is accessible to the attackers. While no fixes or patches are available yet, Microsoft has provided mitigations for on-premises Microsoft Exchange users on Sept. 29, 2022. Even organizations that use Exchange Online may still be affected if they run a hybrid server. Cisco Talos is closely monitoring the recent reports of exploitation attempts against these vulnerabilities and strongly recommends users implement mitigation steps while waiting for securit...
Even organizations that use Exchange Online may still be affected if they run a hybrid server.
By Deeba Ahmed The latest attack against Exchange servers utilizes at least two new flaws (CVE-2022-41040, CVE-2022-41082) that have been assigned CVSS scores of 6.3 and 8.8. This is a post from HackRead.com Read the original post: Microsoft Confirms Two 0-Days Being Exploited Against Exchange Servers
Microsoft Corp. is investigating reports that attackers are exploiting two previously unknown vulnerabilities in Exchange Server, a technology many organizations rely on to send and receive email. Microsoft says it is expediting work on software patches to plug the security holes. In the meantime, it is urging a subset of Exchange customers to enable a setting that could help mitigate ongoing attacks.
The "ProxyNotShell" security vulnerabilities can be chained for remote code execution and total takeover of corporate email platforms.
Categories: Exploits and vulnerabilities Categories: News Tags: Exchange Tags: ProxyShell Tags: remote PowerShell Tags: web shell Tags: CVE-2022-41040 Tags: CVE-2022-41082 Tags: SSRF Tags: RCE Two ProxyShell-like vulnerabilities are being used to exploit Microsoft Exchange Servers (Read more...) The post Two new Exchange Server zero-days in the wild appeared first on Malwarebytes Labs.
Microsoft officially disclosed it investigating two zero-day security vulnerabilities impacting Exchange Server 2013, 2016, and 2019 following reports of in-the-wild exploitation. "The first vulnerability, identified as CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability, while the second, identified as CVE-2022-41082, allows remote code execution (RCE) when PowerShell is
Microsoft officially disclosed it investigating two zero-day security vulnerabilities impacting Exchange Server 2013, 2016, and 2019 following reports of in-the-wild exploitation. "The first vulnerability, identified as CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability, while the second, identified as CVE-2022-41082, allows remote code execution (RCE) when PowerShell is
November 8, 2022 update - Microsoft released security updates for CVE-2022-41040 and CVE-2022-41082. We recommend that customers protect their organizations by applying the updates immediately to affected systems. The options described in the Mitigations section are no longer recommended. For more information, review the Exchange Team blog. Summary Summary On November 8 Microsoft released security updates for two zero-day vulnerabilities affecting Microsoft Exchange Server 2013, Exchange Server 2016, and Exchange Server 2019.