Jenkins is a widely used open-source automation server that assists developers in building, deploying, and automating their projects. As one of the most popular CI/CD tools, Jenkins offers a robust ecosystem of plugins that extend its functionality and provide integrations with various third-party technologies. However, CVE-2022-45396, a recently discovered vulnerability, threatens the security of Jenkins deployments using the SourceMonitor Plugin version .2 and earlier. This blog post will delve into the specifics of this vulnerability, explain why it's a cause for concern, and provide guidance on how to mitigate its potential impact.

Vulnerability Details

The CVE-2022-45396 vulnerability stems from the SourceMonitor Plugin's failure to properly secure its XML parser, leaving it exposed to XML External Entity (XXE) attacks. XXE attacks exploit flaws in the way XML parsers handle external entities, allowing attackers to gain unauthorized access to sensitive data, execute remote code, or launch Denial of Service (DoS) attacks.

The SourceMonitor Plugin enables Jenkins users to integrate with SourceMonitor, a powerful, free static code analyzer that supports multiple programming languages. This Plugin version .2 and earlier does not configure its XML parser in a manner that prevents XXE attacks. Hence, malicious actors who can control the XML data loaded by the SourceMonitor Plugin can exploit this vulnerability to compromise Jenkins systems.

Exploit Details

An attacker exploits the CVE-2022-45396 vulnerability by crafting a malicious XML file containing external entities, which extracts or discloses sensitive information when processed by the SourceMonitor Plugin's XML parser. For example, an attacker could craft an XML file like this:

<!DOCTYPE foo [
<!ELEMENT foo ANY >
<!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
<foo>&xxe;</foo>

In this example, the attacker employs an external entity (&xxe;) to access the /etc/passwd file on the target system when the SourceMonitor Plugin processes the crafted XML file. This potentially exposes critical system files, confidential data, or other sensitive information.

Original References

1. Jenkins Security Advisory: https://www.jenkins.io/security/advisory/2022-03-17/
2. CVE-2022-45396: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-45396
3. SourceMonitor Plugin: https://plugins.jenkins.io/sourcemonitor/

Mitigation Steps

To shield systems from the CVE-2022-45396 vulnerability, the Jenkins project recommends updating the SourceMonitor Plugin to version .3 or later, which addresses the XXE attack risk. Jenkins administrators can complete this update by following these steps:

Click "Download now and install after restart."

Administrators should also ensure that XML parsers used in other plugins and custom integrations are appropriately configured to defend against XXE attacks. Best practices for securing XML parsers can be found in OWASP's XXE Prevention Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html

Conclusion

CVE-2022-45396 reveals the inherent risks associated with third-party plugin integrations in Jenkins and emphasizes the need for regular updates and security checks. Jenkins administrators should always stay informed about emerging vulnerabilities, patch their systems promptly, and adhere to security best practices when deploying and managing Jenkins environments.

By addressing the CVE-2022-45396 vulnerability and configuring XML parsers to prevent XXE attacks, organizations can mitigate the risk of data breaches, unauthorized access, and other potential security threats, ensuring the ongoing safety and integrity of their Jenkins deployments.

Timeline

Published on: 11/15/2022 20:15:00 UTC
Last modified on: 11/20/2022 03:08:00 UTC