CVE-2016-0790 in Jenkins
Summary
by MITRE
CloudBees Jenkins before 1.650 and LTS before 1.642.2 do not use a constant-time algorithm to verify API tokens, which makes it easier for remote attackers to determine API tokens via a brute-force approach.
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Analysis
by VulDB Data Team • 07/12/2022
The vulnerability described in CVE-2016-0790 represents a critical timing attack susceptibility within CloudBees Jenkins continuous integration platform. This flaw affects versions prior to 1.650 for standard releases and 1.642.2 for long-term support editions, creating a significant security risk that adversaries can exploit through carefully crafted brute-force attacks. The vulnerability stems from the implementation of API token verification mechanisms that do not employ constant-time algorithms, thereby leaking timing information that can be used to reverse-engineer valid API tokens.
The technical root cause of this vulnerability lies in the non-constant time comparison operations used during API token validation processes. When Jenkins compares a provided API token against the expected value, the time taken for this comparison varies depending on where the first mismatch occurs in the token string. This timing variation creates a side-channel attack vector that allows remote attackers to perform statistical analysis and determine valid API tokens through repeated attempts. The vulnerability maps directly to CWE-203, which specifically addresses "Information Exposure Through Discrepancy in Time" and aligns with ATT&CK technique T1213.001 for Credential Access through credential dumping and token manipulation.
The operational impact of this vulnerability extends beyond simple credential theft, as API tokens in Jenkins environments typically provide access to critical build systems, repository management, and deployment capabilities. Attackers who successfully obtain valid API tokens can execute arbitrary commands, access sensitive build artifacts, modify pipeline configurations, and potentially escalate privileges within the CI/CD environment. This makes the vulnerability particularly dangerous in enterprise settings where Jenkins serves as a central hub for software development and deployment processes.
Organizations affected by this vulnerability should prioritize immediate remediation through version upgrades to Jenkins 1.650 or LTS 1.642.2, which implement proper constant-time token comparison algorithms. Additional mitigations include implementing rate limiting on authentication attempts, deploying network-level firewalls to restrict access to Jenkins endpoints, and monitoring for unusual authentication patterns that might indicate brute-force attacks. Security teams should also consider implementing multi-factor authentication for Jenkins access and conducting regular security assessments of their CI/CD infrastructure to identify similar timing attack vulnerabilities in other systems. The remediation process should include thorough testing of upgraded environments to ensure that existing functionality remains intact while the security vulnerability is properly addressed.