External risk intelligence

Jenkins CLI Vulnerability Allows Unauthorized File Access

CVE advisoryKnown Exploit

CVE-2024-23897

A Jenkins vulnerability allows unauthenticated attackers to read arbitrary files from the Jenkins controller, potentially exposing sensitive data. This impacts organizations using affected Jenkins versions and presents a business risk due to unauthorized information disclosure. Updates are available to address this iss

4Halo Surface Signal

Path Traversal

Jenkins

before 2.426.3before 2.442

External exposure likelihood

Halo Surface Signal score for CVE-2024-23897

Jenkins is a widely deployed automation server that is frequently exposed to the internet to facilitate remote build, deployment, and integration pipelines. The CLI interface is a core component of the Jenkins controller, which is often reachable in common operational configurations.

Horizon Alert

Summary of the vulnerability and why it matters

Jenkins versions prior to 2.441 and LTS versions prior to 2.426.2 contain a vulnerability that allows unauthenticated attackers to read arbitrary files from the Jenkins controller. This occurs because the system fails to disable a feature within its Command Line Interface (CLI) that expands an '@' symbol followed by a file path into the file's contents. This could expose sensitive information residing on the Jenkins controller.

Vulnerable Jenkins CLI feature
File content expansion flaw
Exposure of sensitive files

Attack Path

How an attacker could exploit the issue

The vulnerability allows unauthenticated attackers to read arbitrary files from the Jenkins controller's file system. This occurs when an '@' character followed by a file path is included in an argument to a Jenkins CLI command. The command parser incorrectly interprets this sequence, replacing it with the file's content, thereby exposing sensitive information. Organizations using affected Jenkins versions are at risk of unauthorized data disclosure.

Jenkins controller exposed externally.
Unauthenticated attacker provides crafted CLI argument.
Attacker reads arbitrary files.

Live Threat

Current exploitation, exposure, and threat context

The identified vulnerability in Jenkins allows unauthenticated attackers to read arbitrary files on the Jenkins controller system. This could lead to the exposure of sensitive information, potentially enabling further system compromise. The vulnerability is present in Jenkins versions prior to 2.442 and LTS 2.426.3.

Likely attacker skill level: Low
Required access or conditions: None (unauthenticated)
Business risk or urgency: Critical

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

An organization faces significant risk due to a critical vulnerability in Jenkins' Command Line Interface (CLI). This flaw allows unauthenticated attackers to read arbitrary files from the Jenkins controller's file system. The widespread use of Jenkins for automation and its frequent exposure to the internet heighten the potential impact of this vulnerability.

Identify Jenkins controller assets.
Disable CLI or restrict network access.
Apply vendor fix, verify, and monitor.

Frequently asked questions

What is the nature of the Jenkins vulnerability CVE-2024-23897 and which versions are affected?

CVE-2024-23897 is a critical vulnerability in Jenkins where the CLI command parser does not disable a feature that replaces an '@' character followed by a file path with the file's contents. This allows unauthenticated attackers to read arbitrary files on the Jenkins controller file system. Jenkins versions 2.441 and earlier, and LTS versions 2.426.2 and earlier, are affected.

What type of weakness allows unauthenticated Jenkins users to read arbitrary files?

This vulnerability is classified under CWE-22 and CWE-27, indicating a Path Traversal (also known as Directory Traversal) weakness. This allows an attacker to access files and directories that are outside of the web root directory that is normally accessible. In this specific case, it enables reading arbitrary files on the Jenkins controller's file system.

How can an attacker exploit the Jenkins vulnerability to read files, and what is the scope of access?

An unauthenticated attacker can exploit this vulnerability by providing a crafted argument to a Jenkins CLI command that starts with an '@' character followed by a file path. The CLI command parser will incorrectly expand this, replacing it with the content of the specified file. The scope of access is the Jenkins controller's file system, meaning an attacker can read any file the Jenkins controller has read access to.

What is the relevance of CVE-2024-23897, and why is it considered critical?

This vulnerability is critical because it allows unauthenticated attackers to read arbitrary files on the Jenkins controller. Jenkins is widely used for automation and is often exposed to the internet, increasing the risk of exploitation. The ability to read sensitive files could lead to further system compromise or data breaches. Halo classifies this CVE as external due to its network attack vector and high impact.

What steps should an organization take to respond to the Jenkins CLI vulnerability?

Organizations should identify all Jenkins controller assets, and if possible, disable the CLI or restrict network access to it. The primary operational fix is to apply the vendor-provided security updates to Jenkins, ensuring versions are updated to 2.442 or later, and LTS versions to 2.426.3 or later. After applying the fix, it is crucial to verify the update and continuously monitor for any suspicious activity.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.