November 14, 2023

CitrixBleed Vulnerability Exploitation Plagues Organizations: A Deep Dive

CitrixBleed Vulnerability Exploitation Plagues Organizations: A Deep Dive


The cybersecurity landscape is rife with challenges, and one such ongoing threat is the exploitation of the CitrixBleed vulnerability. Despite a patch being issued, organizations across various sectors continue to grapple with this persistent issue. In this deep dive, we delve into the details of CitrixBleed, the challenges it presents, and the lessons to be learned from this ongoing cybersecurity battle.

The CitrixBleed Vulnerability:

Citrix NetScaler ADC and NetScaler Gateway users have been exposed to an active and targeted exploitation of a vulnerability known as CitrixBleed. This vulnerability can lead to session hijacking and other malicious activities, posing significant risks to organizations. The Cybersecurity and Infrastructure Security Agency (CISA) has urged organizations to take immediate action by applying the patch, hunting for malicious activity, and reporting their findings.

The Patching Challenge:

Despite the availability of a patch since October 10, organizations have struggled to patch their systems effectively. Caitlin Condon, head of vulnerability research at Rapid7, has noted a steady stream of compromises related to CitrixBleed. It appears that some organizations are finding it challenging to respond swiftly to actively exploited vulnerabilities, highlighting a critical issue in the cybersecurity landscape.

Exploitation Across Industries:

The exploitation of CitrixBleed has not been confined to a single industry. Instead, it has affected organizations in various sectors, including retail, healthcare, and manufacturing. Investigations have revealed that threat actors have engaged in lateral movement and data access, emphasizing the severity and persistence of this threat.

Lockbit's Potential Involvement:

Security researcher Dominic Alvieri has raised concerns about the threat group Lockbit potentially exploiting CitrixBleed. LockBit has previously been linked to threat activity against Boeing, though it remains uncertain whether the Citrix exploit was used to access Boeing's data. This highlights the interconnectedness of cybersecurity threats across different organizations.

Persistent Threat Despite the Patch:

Despite the patch's availability, credible reports of session hijacking and targeted attacks continued to emerge as of October 23. Security researchers speculate that the mass exploitation may be attributed to a combination of slow patch response and patches that do not provide adequate protection. This underscores the importance of timely and effective patch management in cybersecurity defense.

Challenges in Patching:

Dray Agha, U.K. threat operations manager at Huntress, suggests that system administrators may not be patching at the necessary rate to deny threat actors the opportunity to leverage this exploit. Furthermore, patches can sometimes be evadable, allowing adversaries to identify small adjustments needed to re-exploit a vulnerability that was believed to be patched.

Session Persistence and Bypass:

CISA issued urgent warnings for organizations to delete all prior sessions after threat actors managed to bypass the patch, allowing previously authenticated sessions to persist. This represents a significant challenge as attackers can gain unauthorized access even after patch deployment.

Exploitation Techniques:

Reports indicate that exploitation activity included the distribution of Python scripts to ransomware affiliates for exploitation. Palo Alto Networks Unit 42 observed compromised users executing reconnaissance commands and deploying additional tools on virtual desktop infrastructure hosts, highlighting the sophisticated nature of these attacks.


The ongoing exploitation of the CitrixBleed vulnerability serves as a stark reminder of the persistent and evolving nature of cybersecurity threats. Organizations must prioritize proactive patch management, timely response to vulnerabilities, and robust threat detection and mitigation strategies to stay ahead in the ever-changing cybersecurity landscape. The battle against CitrixBleed continues, underscoring the need for constant vigilance and collaboration within the cybersecurity community.

If you would like an understanding of how the CitrixBleed may impact your organization, please contact us today.

Photo by Elti Meshau on Unsplash

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