CVE-2014-3661 in Jenkins
Summary
by MITRE
CloudBees Jenkins before 1.583 and LTS before 1.565.3 allows remote attackers to cause a denial of service (thread consumption) via vectors related to a CLI handshake.
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Analysis
by VulDB Data Team • 03/30/2022
The vulnerability identified as CVE-2014-3661 affects CloudBees Jenkins versions prior to 1.583 and LTS versions prior to 1.565.3, presenting a significant security risk that enables remote attackers to execute denial of service attacks through specifically crafted CLI handshake operations. This vulnerability operates at the core of Jenkins' command line interface functionality, where improper handling of handshake sequences creates exploitable conditions that can be leveraged by malicious actors to consume system resources.
The technical flaw manifests in the Jenkins CLI subsystem where the handshake process fails to properly validate incoming connection requests and authentication sequences. Attackers can exploit this weakness by initiating malformed or excessive CLI handshake requests that cause the Jenkins server to allocate threads unnecessarily, leading to thread exhaustion and ultimately system unresponsiveness. The vulnerability is classified under CWE-400 as a resource exhaustion issue, specifically targeting thread consumption within the application's concurrency model. This represents a classic denial of service vector that can be executed remotely without requiring authentication or elevated privileges.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render Jenkins servers unusable for legitimate users and administrators. When exploited, the vulnerability causes the Jenkins instance to consume all available threads in its thread pool, preventing new connections from being established and causing existing operations to hang or fail. This affects not only the immediate Jenkins server but also any dependent systems that rely on Jenkins for continuous integration and deployment operations. The vulnerability aligns with ATT&CK technique T1499.004 for resource exhaustion attacks and demonstrates how seemingly minor flaws in authentication mechanisms can escalate into critical service availability issues.
Organizations affected by this vulnerability should immediately implement the recommended patches and updates to Jenkins versions 1.583 and LTS 1.565.3, which contain the necessary fixes for the CLI handshake validation. Additional mitigations include implementing network-level restrictions such as firewall rules that limit CLI access to trusted IP addresses, configuring rate limiting on CLI connections, and monitoring thread usage patterns to detect potential exploitation attempts. System administrators should also consider implementing intrusion detection systems that can identify suspicious CLI handshake patterns and automatically block malicious traffic. The vulnerability highlights the importance of proper input validation and resource management in distributed systems, particularly those handling authentication and connection management functions.