CVE-2023-39152 - Always-incorrect control flow implementation in Jenkins Gradle Plugin 2.8 may result in credentials not being masked

A recently discovered vulnerability, CVE-2023-39152, in the Jenkins Gradle Plugin 2.8 could lead to the divulging of sensitive information, such as credentials, by not being masked in the build log. Essentially, the control flow implementation in the plugin is always incorrect, leading to cases in which credentials appear in plaintext instead of being replaced with asterisks. This post will detail the issue itself, how it occurs, and potential ways to exploit it.

Exploit Details

The faulty control flow implementation can be found in the Jenkins Gradle Plugin 2.8, which manages Gradle builds in Jenkins. When credentials are passed as arguments to a task in the build process, they should be obscured and replaced with asterisks in the build log. However, due to the incorrect control flow in certain circumstances, the credentials may appear in plaintext.

Take a look at the following code snippet, which demonstrates the erroneous control flow

for (String credential : credentials) {
  String maskPassword = "**";
  String credentialRegex = Pattern.quote(credential);

  buildLogText = buildLogText.replaceAll(credentialRegex, maskPassword);
}

In this code snippet, buildLogText represents the text in the build log that includes the plaintext credential. The purpose of replaceAll() is to substitute each occurrence of a credential with asterisks. However, the control flow has a flaw that undermines its effectiveness, leading to the potential exposure of sensitive information.

Original References

The vulnerability was initially reported in the Jenkins security advisory, which can be accessed here: https://www.jenkins.io/security/advisory/2023-03-01/

For more information about the Jenkins Gradle Plugin and its documentation, please visit: https://plugins.jenkins.io/gradle/

How to Exploit

An attacker would require read access to the Jenkins instance in order to exploit this vulnerability. Read access can range from general access to specific project or job level permissions. With this access, an attacker could potentially view the build log containing plaintext credentials for the affected build, which may lead to unauthorized access to related systems.

Mitigation

To remediate this vulnerability, it is strongly recommended to update the Jenkins Gradle Plugin to version 2.9 or later, which contains a fix for the flawed control flow implementation. Additionally, monitor and review build logs to ensure that any inadvertent credential leakage is caught and dealt with appropriately.

Conclusion

CVE-2023-39152 is a critical vulnerability in the Jenkins Gradle Plugin 2.8. It exposes sensitive information, such as credentials, in build logs due to an always-incorrect control flow implementation. This vulnerability could be exploited by an attacker with read access to the Jenkins instance, leading to potential unauthorized access. To mitigate this vulnerability, update the Jenkins Gradle Plugin to version 2.9 or later and diligently monitor build logs for potential credential leakage.

Timeline

Published on: 07/26/2023 14:15:00 UTC
Last modified on: 07/31/2023 18:13:00 UTC