CVE-2017-1000092 in Jenkins
Summary
by MITRE
Git Plugin connects to a user-specified Git repository as part of form validation. An attacker with no direct access to Jenkins but able to guess at a username/password credentials ID could trick a developer with job configuration permissions into following a link with a maliciously crafted Jenkins URL which would result in the Jenkins Git client sending the username and password to an attacker-controlled server.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/22/2019
The vulnerability described in CVE-2017-1000092 represents a critical security flaw in the Jenkins Git Plugin that exploits a combination of trust assumptions and user interaction patterns within the Jenkins environment. This issue specifically targets the form validation process where the Git Plugin attempts to connect to user-specified Git repositories, creating an attack surface that can be leveraged by remote adversaries. The vulnerability operates under the premise that an attacker can guess valid credential IDs within the Jenkins system while maintaining no direct access to the Jenkins instance itself, demonstrating how indirect attack vectors can compromise even well-protected systems. The flaw is particularly concerning because it relies on social engineering techniques to propagate, requiring minimal technical expertise from the attacker while potentially causing significant damage to the organization's source code repositories.
The technical implementation of this vulnerability stems from the Git Plugin's improper handling of repository validation requests, where it automatically attempts to establish connections to Git repositories using stored credentials without sufficient verification of the destination server. This behavior creates a scenario where a maliciously crafted Jenkins URL can redirect the Git client to an attacker-controlled server, effectively enabling credential theft through what appears to be legitimate administrative functions. The flaw is categorized under CWE-200, which deals with information exposure, and specifically manifests as an improper restriction of operations within a recognized security boundary. The vulnerability demonstrates a classic case of insecure direct object reference where the system fails to properly validate the destination of network requests, allowing attackers to redirect authenticated connections to malicious endpoints.
From an operational impact perspective, this vulnerability enables attackers to gain unauthorized access to Git repositories through the theft of valid username and password combinations, potentially leading to code injection, data exfiltration, and complete compromise of source code integrity. The attack requires only that an attacker can guess valid credential IDs and convince a developer with job configuration permissions to click on a malicious link, making it particularly dangerous in environments where developers have elevated privileges. The vulnerability can result in continuous credential exposure as long as the malicious URL remains active, potentially allowing attackers to maintain persistent access to sensitive repositories. This threat is exacerbated by the fact that the attack can occur without direct access to the Jenkins server, making it difficult to detect through traditional network monitoring approaches and highlighting the importance of proper input validation and secure coding practices.
Organizations should implement immediate mitigations including restricting access to job configuration pages for users who do not require such privileges, implementing strict URL validation for all Jenkins links, and configuring proper network segmentation to prevent unauthorized access to Jenkins instances. The recommended approach involves establishing a comprehensive credential management policy that includes regular credential rotation, implementing multi-factor authentication for sensitive systems, and deploying network monitoring solutions that can detect unusual patterns of credential usage. Additionally, organizations should consider implementing automated security scanning tools that can identify vulnerable plugins and ensure all Jenkins components are regularly updated to prevent exploitation of known vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1078 for valid accounts and T1566 for phishing, emphasizing the need for both technical controls and user awareness training to prevent successful exploitation.