Jenkins is a widely used open-source automation server that helps automate parts of the software development process. A recent vulnerability, referenced as CVE-2023-41930, has been discovered in the Jenkins Job Configuration History Plugin, affecting versions 1227.v7a_79fc4dc01f and earlier. This vulnerability allows attackers to have Jenkins render a manipulated configuration history that was not created by the plugin. In this blog post, we will take a closer look at this vulnerability, its impact, and the steps necessary to mitigate the risk.
Description of Vulnerability
The Jenkins Job Configuration History Plugin allows users to view, manage, and compare configuration changes over time. However, in versions 1227.v7a_79fc4dc01f and earlier, the plugin fails to properly restrict the 'name' query parameter when rendering a history entry. This could allow an attacker to manipulate the configuration history and have Jenkins render a configuration history that was not originally created by the plugin.
A successful exploit of this vulnerability could lead to an attacker obtaining sensitive information or compromising the integrity of the Jenkins server.
Exploit Details
The following code snippet demonstrates an example of exploiting the vulnerability by crafting a malicious 'name' query parameter and passing it to the Jenkins server:
GET /jenkins/jobConfigHistory/showConfig?urlName=..%2Fjobs%2Fmalicious_job_name%2FconfigHistory HTTP/1.1
Host: example.com
User-Agent: ...
Cookie: ...
This request would prompt the Jenkins server to render the manipulated configuration history, which could contain sensitive information or cause harm to the system.
Original References
The vulnerability was initially reported by an independent security researcher who published their findings on GitHub:
- GitHub Advisory: https://github.com/advisories/GHSA-cww8-6x6m-j23f
- Jenkins Security Advisory: https://www.jenkins.io/security/advisory/2023-04-18/#SECURITY-2695
To protect your Jenkins server from this vulnerability, follow these steps
1. Update the Jenkins Job Configuration History Plugin to version 1227.vcfe9de9f31a or later. This version addresses the vulnerability by properly restricting the 'name' query parameter when rendering a history entry.
The updated plugin can be found on the Jenkins plugin site: https://plugins.jenkins.io/jobConfigHistory/
2. Regularly review user access to your Jenkins server and limit permissions to those necessary for a user's job function. Ideally, only trusted users should be able to access configuration history.
3. Apply the principle of least privilege and use security best practices to further reduce the risk of exploitation.
4. Monitor your Jenkins server logs for any suspicious activity that could indicate a possible attack or unauthorized access.
Conclusion
While the vulnerability in the Jenkins Job Configuration History Plugin (CVE-2023-41930) poses a risk to users with outdated versions, affected installations can easily be protected by updating the plugin to the latest version and implementing the recommended security measures. By taking these steps, users can ensure the safety and security of their Jenkins server and prevent potential attackers from exploiting this vulnerability.
Timeline
Published on: 09/06/2023 13:15:09 UTC
Last modified on: 09/11/2023 19:23:34 UTC