Security
Headlines
HeadlinesLatestCVEs

Headline

Critical Citrix Bug Exploited as a Zero-Day, 'Patching Is Not Enough'

The latest threat to Citrix NetScaler, CVE-2023-4966, was exploited as a zero-day bug for months before a patch was issued. Researchers expect exploitation efforts to surge.

DARKReading
#vulnerability#backdoor#auth#zero_day

A critical security vulnerability in Citrix NetScaler patched last week is under active attack — and has been since at least August.

Making matters worse, the bug (CVE-2023-4966, CVSS score 9.4), can’t be fully remediated by simply applying the patch, Mandiant warns.

To that point, “organizations should … terminate all active sessions,” Mandiant CTO Charles Carmakal explained in a LinkedIn post on the active Citrix exploitation this week. “These authenticated sessions will persist after the update to mitigate CVE-2023-4966 has been deployed. Therefore, even after the patch is applied, a threat actor could use stolen session data to authenticate to resources until the sessions are terminated.”

Technically an information-disclosure vulnerability, the flaw allows cyberattackers to hijack existing authenticated sessions and potentially bypass multifactor authentication (MFA). The result is full control over NetScaler environments, which control and manage application delivery within enterprises.

Zero-Day Exploitation Since August

Mandiant has traced attacks exploiting the bug back to late summer, carried out by an unknown threat actor. Carmakal said that the ongoing exploitation appears focused on cyberespionage, with professional services, technology, and government organizations so far in the unknown attackers’ sights.

“We anticipate other threat actors with financial motivations will exploit this over time,” he added.

That’s a likely prediction given that organizations have a poor track record when it comes to mitigating known threats against Citrix gear. For instance, earlier in the month it came to light that legions of attackers are still targeting CVE-2023-3519 (CVSS score of 9.8), a critical pre-authentication remote code-execution (RCE) vulnerability in Citrix NetScaler gateways that was addressed in July (but exploited as a zero-day for a month before that).

Thousands of credential-theft attacks ensued after the disclosure, cresting in August as patching lagged. As of early October, according to the Shadowserver Foundation, more than 1,300 backdoored NetScaler instances were still appearing in scans.

As far as the latest critical security bug goes, customer-managed Citrix NetScaler ADC and NetScaler Gateway installations are affected; cloud instances are not, as outlined in the Citrix bug advisory, which also includes information about patched versions. Mandiant on Wednesday also offered updated, detailed remediation guidance for CVE-2023-4966.

Related news

Zero-Days Win the Prize for Most Exploited Vulns

Among the top exploited zero-day vulnerabilities were bugs found in systems from Citrix and Cisco.

RansomHub Ransomware Group Targets 210 Victims Across Critical Sectors

Threat actors linked to the RansomHub ransomware group encrypted and exfiltrated data from at least 210 victims since its inception in February 2024, the U.S. government said. The victims span various sectors, including water and wastewater, information technology, government services and facilities, healthcare and public health, emergency services, food and agriculture, financial services,

U.S. Agencies Warn of Iranian Hacking Group's Ongoing Ransomware Attacks

U.S. cybersecurity and intelligence agencies have called out an Iranian hacking group for breaching multiple organizations across the country and coordinating with affiliates to deliver ransomware. The activity has been linked to a threat actor dubbed Pioneer Kitten, which is also known as Fox Kitten, Lemon Sandstorm (formerly Rubidium), Parisite, and UNC757, which it described as connected to

Citrix, VMware, and Atlassian Hit with Critical Flaws — Patch ASAP!

Citrix is warning of two zero-day security vulnerabilities in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway) that are being actively exploited in the wild. The flaws are listed below - CVE-2023-6548 (CVSS score: 5.5) - Authenticated (low privileged) remote code execution on Management Interface (requires access to NSIP, CLIP, or SNIP with management

Ransomware review: December 2023

In November, ransomware gangs attacked at least 457 victims—the highest monthly count in 2023, after May's record numbers.

Citrix Bleed widely exploitated, warn government agencies

Citrix Bleed is being actively exploited by at least six cybercrime groups.

LockBit Ransomware Exploiting Critical Citrix Bleed Vulnerability to Break In

Multiple threat actors, including LockBit ransomware affiliates, are actively exploiting a recently disclosed critical security flaw in Citrix NetScaler application delivery control (ADC) and Gateway appliances to obtain initial access to target environments. The joint advisory comes from the U.S. Cybersecurity and Infrastructure Security Agency (CISA), Federal Bureau of Investigation (FBI),

Lockbit Ransomware Leaks Boeing Data Trove

By Deeba Ahmed Earlier, Boeing acknowledged a cyberattack amidst claims by the Lockbit ransomware gang of breaching its security and stealing data. This is a post from HackRead.com Read the original post: Lockbit Ransomware Leaks Boeing Data Trove

World’s Largest Bank ICBC Discloses Crippling Ransomware Attack

By Deeba Ahmed Reportedly, it was a ransomware attack orchestrated by the notorious LockBit gang. This is a post from HackRead.com Read the original post: World’s Largest Bank ICBC Discloses Crippling Ransomware Attack

October 2023: back to Positive Technologies, Vulristics updates, Linux Patch Wednesday, Microsoft Patch Tuesday, PhysTech VM lecture

Hello everyone! October was an interesting and busy month for me. I started a new job, worked on my open source Vulristics project, and analyzed vulnerabilities using it. Especially Linux vulnerabilities as part of my new Linux Patch Wednesday project. And, of course, analyzed Microsoft Patch Tuesday as well. In addition, at the end of […]

You’d be surprised to know what devices are still using Windows CE

The Arid Viper threat actor is actively trying to install spyware on targeted devices in the Middle East, using fake dating apps as lures.

Mandiant Tracks Four Uncategorized Groups Exploiting Citrix Vulnerability

By Waqas Mandiant Investigates Zero-Day Exploitation in Citrix Vulnerability, CVE-2023-4966. This is a post from HackRead.com Read the original post: Mandiant Tracks Four Uncategorized Groups Exploiting Citrix Vulnerability

CVE-2023-4967: NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-4966 and CVE-2023-4967

Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual Server

As Citrix Urges Its Clients to Patch, Researchers Release an Exploit

In the race over Citrix's latest vulnerability, the bad guys have a huge head start, with broad implications for businesses and critical infrastructure providers worldwide.

Alert: PoC Exploits Released for Citrix and VMware Vulnerabilities

Virtualization services provider VMware has alerted customers to the existence of a proof-of-concept (PoC) exploit for a recently patched security flaw in Aria Operations for Logs. Tracked as CVE-2023-34051 (CVSS score: 8.1), the high-severity vulnerability relates to a case of authentication bypass that could lead to remote code execution. "An unauthenticated, malicious actor can inject files

Critical Citrix NetScaler Flaw Exploited to Target from Government, Tech Firms

Citrix is warning of exploitation of a recently disclosed critical security flaw in NetScaler ADC and Gateway appliances that could result in exposure of sensitive information. Tracked as CVE-2023-4966 (CVSS score: 9.4), the vulnerability impacts the following supported versions - NetScaler ADC and NetScaler Gateway 14.1 before 14.1-8.50 NetScaler ADC and NetScaler Gateway 13.1 before

CVE-2023-4966: NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-4966 and CVE-2023-4967

Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA ?virtual?server. 

Citrix Devices Under Attack: NetScaler Flaw Exploited to Capture User Credentials

A recently disclosed critical flaw in Citrix NetScaler ADC and Gateway devices is being exploited by threat actors to conduct a credential harvesting campaign. IBM X-Force, which uncovered the activity last month, said adversaries exploited "CVE-2023-3519 to attack unpatched NetScaler Gateways to insert a malicious script into the HTML content of the authentication web page to capture user

Citrix NetScaler Alert: Ransomware Hackers Exploiting Critical Vulnerability

Unpatched Citrix NetScaler systems exposed to the internet are being targeted by unknown threat actors in what's suspected to be a ransomware attack. Cybersecurity company Sophos is tracking the activity cluster under the moniker STAC4663. Attack chains involve the exploitation of CVE-2023-3519, a critical code injection vulnerability impacting NetScaler ADC and Gateway servers that could

CISA Adds Citrix ShareFile Flaw to KEV Catalog Due to In-the-Wild Attacks

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a critical security flaw in Citrix ShareFile storage zones controller to its Known Exploited Vulnerabilities (KEV) catalog, based on evidence of active in-the-wild exploitation. Tracked as CVE-2023-24489 (CVSS score: 9.8), the shortcoming has been described as an improper access control bug that, if successfully exploited

Citrix NetScalers backdoored in widespread exploitation campaign

Categories: Exploits and vulnerabilities Categories: News Tags: Citrix Tags: NetScalers Tags: Germany Tags: CVE-2023-3519 Tags: Fox-IT Tags: DIVD Researchers have found almost 2000 backdoored Citrix NetScalers, many of which were patched after the backdoor in the form of a web shell was dropped. (Read more...) The post Citrix NetScalers backdoored in widespread exploitation campaign appeared first on Malwarebytes Labs.

Nearly 2,000 Citrix NetScaler Instances Hacked via Critical Vulnerability

Nearly 2,000 Citrix NetScaler instances have been compromised with a backdoor by weaponizing a recently disclosed critical security vulnerability as part of a large-scale attack. "An adversary appears to have exploited CVE-2023-3519 in an automated fashion, placing web shells on vulnerable NetScalers to gain persistent access," NCC Group said in an advisory released Tuesday. "The adversary can

Citrix ADC (NetScaler) Remote Code Execution

A vulnerability exists within Citrix ADC that allows an unauthenticated attacker to trigger a stack buffer overflow of the nsppe process by making a specially crafted HTTP GET request. Successful exploitation results in remote code execution as root.

Hundreds of Citrix NetScaler ADC and Gateway Servers Hacked in Major Cyber Attack

Hundreds of Citrix NetScaler ADC and Gateway servers have been breached by malicious actors to deploy web shells, according to the Shadowserver Foundation. The non-profit said the attacks take advantage of CVE-2023-3519, a critical code injection vulnerability that could lead to unauthenticated remote code execution. The flaw, patched by Citrix last month, carries a CVSS score of 9.8. The

CISA: You've got two weeks to patch Citrix NetScaler vulnerability CVE-2023-3519

Categories: Exploits and vulnerabilities Categories: News Tags: Citrix Tags: NetScaler Tags: CVE-2023-3519 Tags: web shell A critical unauthenticated remote code execution vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway is being actively exploited (Read more...) The post CISA: You've got two weeks to patch Citrix NetScaler vulnerability CVE-2023-3519 appeared first on Malwarebytes Labs.

Citrix NetScaler ADC and Gateway Devices Under Attack: CISA Urges Immediate Action

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) issued an advisory on Thursday warning that the newly disclosed critical security flaw in Citrix NetScaler Application Delivery Controller (ADC) and Gateway devices is being abused to drop web shells on vulnerable systems. "In June 2023, threat actors exploited this vulnerability as a zero-day to drop a web shell on a critical

DARKReading: Latest News

Faux ChatGPT, Claude API Packages Deliver JarkaStealer