CVE-2017-2607 in Jenkins
Summary
by MITRE
jenkins before versions 2.44, 2.32.2 is vulnerable to a persisted cross-site scripting vulnerability in console notes (SECURITY-382). Jenkins allows plugins to annotate build logs, adding new content or changing the presentation of existing content while the build is running. Malicious Jenkins users, or users with SCM access, could configure jobs or modify build scripts such that they print serialized console notes that perform cross-site scripting attacks on Jenkins users viewing the build logs.
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Analysis
by VulDB Data Team • 03/14/2023
The vulnerability described in CVE-2017-2607 represents a critical persisted cross-site scripting flaw within Jenkins continuous integration platform affecting versions prior to 2.44 and 2.32.2. This security weakness specifically targets the console notes functionality that allows plugins to annotate build logs and modify their presentation during active builds. The vulnerability falls under CWE-79 which categorizes cross-site scripting attacks as a result of improper input validation and output encoding. The attack vector leverages the legitimate console notes feature to inject malicious scripts that persist in build logs and execute when other users view these logs, creating a sophisticated attack scenario that combines both server-side and client-side exploitation techniques.
The technical flaw stems from inadequate sanitization of user-supplied data within Jenkins console notes functionality. When malicious actors with sufficient privileges configure jobs or modify build scripts, they can craft serialized console notes that contain malicious javascript payloads. These payloads are then embedded within the build log output and executed in the context of other users' browsers when they view the build logs. This represents a classic persisted XSS vulnerability where the malicious content is stored on the server and delivered to victims upon subsequent page requests. The vulnerability is particularly dangerous because it can be exploited by users with SCM access or those who can modify job configurations, making it accessible to both internal attackers and compromised accounts.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to perform a wide range of malicious activities through the victim's Jenkins session. Attackers can execute arbitrary javascript code in the context of authenticated Jenkins users, potentially allowing them to access sensitive build information, modify job configurations, or even escalate their privileges within the Jenkins environment. The vulnerability affects users who view build logs, creating a broad attack surface since Jenkins administrators, developers, and other authorized personnel regularly access these logs. This makes the attack particularly insidious as it can be triggered simply by viewing a compromised build log, requiring no additional user interaction beyond normal system usage. The security implications align with ATT&CK technique T1059.007 for script execution and T1566 for credential access through compromised applications.
Mitigation strategies for CVE-2017-2607 involve immediate patching of Jenkins installations to versions 2.44 or 2.32.2, which contain the necessary security fixes. Organizations should also implement strict access controls and privilege management to limit who can modify build scripts and job configurations. Additional defensive measures include regular security audits of Jenkins plugins, implementation of content security policies to limit script execution, and monitoring of console notes functionality for suspicious activity. The vulnerability highlights the importance of input validation and output encoding practices, particularly when dealing with user-generated content that is subsequently rendered in web browsers. Organizations should also consider implementing web application firewalls and regular security training for Jenkins administrators to recognize and prevent potential exploitation attempts. The fix addresses the core issue by properly sanitizing console note content and ensuring that user-supplied data cannot be executed as javascript code, thereby preventing the persistence and execution of malicious payloads in build logs.