CVE-2023-3519 Detection: RCE Zero-Day in Citrix NetScaler ADC and NetScaler Gateway Exploited in the Wild

Heads up! Cybersecurity experts notify defenders of a zero-day flaw compromising Citrix NetScaler Application Delivery Controller (ADC) and NetScaler Gateway Appliances. The flaw tracked as CVE-2023-3519 can lead to RCE and is observed to be actively leveraged by adversaries in the wild with the PoC exploit released to GitHub.

Detect CVE-2023-3519 Exploitation Attempts

The growing volume of attacks weaponizing CVE-2023-3519 to proceed with intrusions in an automated fashion poses an increasing menace for cyber defenders. To identify possible intrusions at the earliest stages, SOC Prime Platform for collective cyber defense offers a set of curated Sigma rues aimed at CVE-2023-3519 exploit detection. 

All rules are compatible with 28 SIEM, EDR, XDR, and Data Lake technologies and mapped to MITRE ATT&CK v12 to streamline threat hunting operations and smooth out the deep dive into the critical threat. 

To explore the full list of rules addressing the security issue in the spotlight, hit the Explore Detections button below. Security professionals can reach extensive cyber threat context accompanied by ATT&CK references and CTI links, as well as obtain more relevant metadata matching current security needs and boosting threat investigation.

Explore Detections

CVE-2023-3519 Analysis

In response to the increasing attack attempts relying on CVE-2023-3519 RCE, with the CVSS score reaching 9.8, Mandiant researchers have recently published an IOC scanning tool to enable defenders to check their Citrix devices for any traces of compromise.

The flaw came to the limelight in mid-July 2023, immediately causing a stir in the cyber threat arena with the increasing claims of its active exploitation in the wild. The vulnerability enables adversaries to perform RCE on the targeted NetScaler ADC (formerly called Citrix ADC) and NetScaler Gateway appliances. Adversaries can weaponize the CVE-2023-3519 flaw by uploading files with malicious web shells and scripts, enabling them to scan the environment and steal sensitive data. A PoC exploit for CVE-2023-3519 that applies related addresses and shellcode is currently available on GitHub.

To raise cybersecurity awareness, Citrix instantly issued a related security heads-up, striving to timely warn defenders of the potential exploitation attempts of CVE-2023-3519 along with other flaws impacting NetScaler users, including CVE-2023-3466 and CVE-2023-3467. In the corresponding security bulletin, NetScaler customers were prompted to upgrade their potentially compromised instances to the latest software versions addressing the vulnerabilities. However, cybersecurity researchers from the Shadowserver Foundation uncovered that even after releasing the updates by Citrix, over 15,000 appliances were later exposed to the related in-the-wild attacks abusing the security bug. 

The emerging volumes of attacks leveraging the CVE-2023-3519 zero-day with thousands of Citrix NetScaler instances potentially affected require ultra-responsiveness from defenders. Rely on Uncoder AI to search for the presence of related indicators of compromise and instantly generate IOC queries ready to run in your SIEM or EDR environment while shaving seconds off threat investigation.