CVE-2024-23897 is a high-severity arbitrary file read vulnerability affecting the popular Jenkins automation server. It stems from an issue in the command line interface (CLI) feature, allowing an attacker to read any file on the Jenkins controller's file system. This flaw lets unauthenticated attackers read the first few lines of files, while attackers with "Overall/Read" permissions can access entire files. This can lead to remote code execution (RCE) by exposing sensitive information like cryptographic keys.
When was it discovered?
The CVE-2024-23897 vulnerability was publicly disclosed by Jenkins as part of a security advisory on January 24, 2024. The advisory detailed this vulnerability along with several others affecting the Jenkins core and various plugins. Security researchers quickly began analyzing the flaw, with proof-of-concept exploits emerging shortly after the public announcement.
Affected products & versions
The vulnerability impacts multiple versions of the Jenkins automation server. Organizations using these versions should prioritize updating immediately.
Product | Versions Affected | Fixed Versions / Patch Links |
Jenkins | <= 2.441 | Jenkins 2.442 |
Jenkins LTS | <= 2.426.2 | Jenkins LTS 2.426.3 |
CVE-2024-23897 Technical Description
This vulnerability is a classic case of path traversal, but with a twist. The problem lies within the args4j library used by Jenkins to parse command-line arguments. The CLI command parser has a feature that automatically expands an @ character followed by a file path, replacing it with the file's contents. This is intended to simplify passing long arguments.
The catch? The parser didn't properly validate the file paths before reading them. An attacker could craft a CLI command that uses this @ feature to point to any file on the server's file system. For example, a command sent to the Jenkins CLI could include @/etc/passwd, causing the server to read the contents of that file. For unauthenticated attackers, the exposure is limited, but attackers with basic read permissions can escalate their privileges significantly, potentially achieving full remote code execution by stealing secrets stored on the server.
Tactics, Techniques & Procedures (TTPs)
Attackers exploiting CVE-2024-23897 typically start with reconnaissance to identify vulnerable Jenkins instances. They then use the file read capability to exfiltrate sensitive files, such as SSH keys, credentials, or other secrets stored on the file system. With these secrets, they can move laterally across the network, escalate privileges, and ultimately deploy other malware like webshells or ransomware. This is a fast track from a simple file read to a full-blown system compromise.
Indicators of Compromise
Keep an eye out for unusual requests to the Jenkins CLI endpoint, specifically those containing the @ character followed by a file path in the arguments. Suspicious log entries in Jenkins access logs or web server logs showing requests to endpoints like /cli can be a dead giveaway. Monitoring for unexpected outbound connections from the Jenkins server can also help spot data exfiltration attempts. A robust Identity, Detection, Threat, and Response (ITDR) solution can help you catch these unusual behaviors before they escalate.
Known Proof-of-Concepts & Exploits
Within hours of the vulnerability's disclosure, multiple proof-of-concept (PoC) exploits for CVE-2024-23897 were published on platforms like GitHub. These PoCs demonstrated how easy it is to read arbitrary files from a vulnerable Jenkins server. Security researchers and threat actors alike have since integrated these exploits into their toolkits. Active exploitation has been observed in the wild, with attackers scanning for and compromising unpatched Jenkins instances.
How to Detect CVE-2024-23897 Vulnerability?
Detecting this vulnerability requires a mix of proactive scanning and log analysis. You can use vulnerability scanners to check if your Jenkins version is affected. For host-based detection, monitor Jenkins application logs and web server access logs for requests to the CLI endpoint. A SIEM rule could flag any CLI command containing the @ character in its arguments, as this is the core of the exploit. Correlating these logs with unusual process execution or network connections from the Jenkins controller provides another layer of detection. A strong Endpoint Detection and Response (EDR) tool is essential for spotting post-exploit activity.
Impact & Risk of CVE-2024-23897 Vulnerability
Don't underestimate this one. The impact of CVE-2024-23897 is severe. Successful exploitation can lead to the complete compromise of your Jenkins controller. This means an attacker can steal source code, credentials, API keys, and other secrets used in your CI/CD pipelines. From there, they can execute arbitrary code on the server, pivot to other systems in your network, and deploy ransomware. The risk to data confidentiality, integrity, and availability is massive, potentially grinding your development and deployment operations to a halt.
Mitigation & Remediation Strategies
Patch, patch, patch! The most effective way to remediate CVE-2024-23897 is to update your Jenkins instance to a patched version (Jenkins 2.442 or LTS 2.426.3). If you can't patch immediately, Jenkins provided a temporary workaround: disable access to the CLI. This stops the exploit vector cold. You can achieve this by applying a system property at startup. Long-term, you should restrict network access to your Jenkins controller, ensuring it's not exposed to the public internet. Regular Security Awareness Training (SAT) for your dev team on secure coding practices can also help prevent similar issues in the future.
CVE-2024-23897 Vulnerability FAQs
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