NetScaler ADC and NetScaler Gateway version 12.1, now end of life.NetScaler ADC and NetScaler Gateway 13.0 before 13.0-91.13.NetScaler ADC and NetScaler Gateway 13.1 before 13.1-49.13.CVE-2023-3519ĬVE-2023-3519 is an unauthenticated RCE vulnerability affecting the following versions of NetScaler ADC and NetScaler Gateway:

Citrix released a patch on July 18, 2023. Citrix confirmed that the actors exploited a zero-day vulnerability: CVE-2023-3519. In July 2023, a critical infrastructure organization reported to CISA that threat actors may have exploited a zero-day vulnerability in NetScaler ADC to implant a webshell on their non-production NetScaler ADC appliance. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool. See the MITRE ATT&CK Tactics and Techniques section for a table of the threat actors’ activity mapped to MITRE ATT&CK® tactics and techniques. Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 13. If no compromise is detected, organizations should immediately apply patches provided by Citrix. If potential compromise is detected, organizations should apply the incident response recommendations provided in this CSA. CISA encourages critical infrastructure organizations to use the detection guidance included in this advisory for help with determining system compromise. This advisory provides tactics, techniques, and procedures (TTPs) and detection methods shared with CISA by the victim. Citrix released a patch for this vulnerability on July 18, 2023. The victim organization identified the compromise and reported the activity to CISA and Citrix. The actors attempted to move laterally to a domain controller but network-segmentation controls for the appliance blocked movement. The webshell enabled the actors to perform discovery on the victim’s active directory (AD) and collect and exfiltrate AD data.

In June 2023, threat actors exploited this vulnerability as a zero-day to drop a webshell on a critical infrastructure organization’s non-production environment NetScaler ADC appliance. The Cybersecurity and Infrastructure Security Agency (CISA) is releasing this Cybersecurity Advisory to warn network defenders about exploitation of CVE-2023-3519, an unauthenticated remote code execution (RCE) vulnerability affecting NetScaler (formerly Citrix) Application Delivery Controller (ADC) and NetScaler Gateway.

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