CVE-2023-27903 : Security Advisory and Response

This article provides insights into CVE-2023-27903, a security vulnerability impacting Jenkins.

Understanding CVE-2023-27903

CVE-2023-27903 is a vulnerability found in Jenkins, specifically in versions 2.393 and earlier, LTS 2.375.3, and earlier. The vulnerability involves the creation of a temporary file in the default temporary directory with default permissions for newly created files when uploading a file parameter through the CLI. This issue could potentially allow attackers with access to the Jenkins controller file system to read and write the file before it is utilized.

What is CVE-2023-27903?

CVE-2023-27903 is a security flaw in Jenkins that arises when handling file uploads through the CLI. Attackers exploiting this vulnerability could gain unauthorized access to sensitive files, compromising the integrity and confidentiality of the system.

The Impact of CVE-2023-27903

The impact of CVE-2023-27903 could be severe as it allows unauthorized users to manipulate files on the Jenkins controller file system before the intended use. This could lead to unauthorized data access, modification, or potential system compromise.

Technical Details of CVE-2023-27903

This section delves into the technical aspects of CVE-2023-27903, shedding light on the vulnerability, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability in Jenkins 2.393 and earlier, LTS 2.375.3 and earlier stems from the insecure creation of temporary files with default permissions during file uploads via the CLI. This insecure file handling opens up possibilities for unauthorized access and manipulation by malicious actors.

Affected Systems and Versions

The affected systems include Jenkins instances running versions 2.393 and earlier, LTS 2.375.3, and earlier. It is crucial for users of these versions to take immediate action to secure their systems against potential exploitation.

Exploitation Mechanism

Exploiting CVE-2023-27903 involves leveraging the insecure temporary file creation process when uploading files through the Jenkins CLI. Attackers with access to the Jenkins controller file system can take advantage of these vulnerabilities to read and write files before their proper utilization.

Mitigation and Prevention

To mitigate the risks associated with CVE-2023-27903, users and administrators are advised to take immediate steps, implement long-term security practices, and apply relevant patches and updates.

Immediate Steps to Take

Users should upgrade their Jenkins instances to versions where the vulnerability is patched.
Limit access to the Jenkins controller file system to authorized personnel only.
Monitor file system activities for any suspicious behavior.

Long-Term Security Practices

Regularly update and patch Jenkins installations to ensure the latest security fixes are applied.
Implement strong access controls and authentication mechanisms to restrict unauthorized access to sensitive areas.

Patching and Updates

Users are recommended to update their Jenkins installations to versions that contain fixes for CVE-2023-27903. Regularly checking for security advisories from Jenkins and promptly applying patches is crucial to maintain a secure environment.