CVE-2020-2103 in Jenkins
Summary
by MITRE
Jenkins 2.218 and earlier, LTS 2.204.1 and earlier exposed session identifiers on a user's detail object in the whoAmI diagnostic page.
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Analysis
by VulDB Data Team • 03/27/2024
This vulnerability exists in Jenkins versions prior to 2.218 and LTS 2.204.1 where session identifiers are improperly exposed through the whoAmI diagnostic page. The flaw allows unauthorized users to access sensitive session information that should remain confidential within the user detail object. When users navigate to the whoAmI endpoint, the system inadvertently includes session tokens and identifiers that can be exploited by attackers to impersonate legitimate users. This exposure occurs due to insufficient input validation and output sanitization mechanisms within the diagnostic page functionality.
The technical implementation of this vulnerability stems from improper access control measures and inadequate data filtering within the Jenkins web interface. The whoAmI page is designed for diagnostic purposes but fails to properly sanitize output data before rendering it to users. Session identifiers are stored in memory and accessible through the user detail object, but the system does not adequately restrict access to this sensitive information. Attackers can leverage this exposure to perform session hijacking attacks and gain unauthorized access to user accounts. The vulnerability directly relates to CWE-200, which covers exposure of sensitive information to an unauthorized actor, and CWE-352, which addresses cross-site request forgery issues that can arise from improper session handling.
The operational impact of this vulnerability extends beyond simple information disclosure as it creates a pathway for authenticated attacks and privilege escalation. An attacker who can access the whoAmI diagnostic page can extract session tokens and use them to impersonate users within the Jenkins environment. This compromises the integrity of the authentication system and can lead to complete system compromise if the compromised sessions have administrative privileges. The vulnerability affects all users who have access to the diagnostic page, making it particularly dangerous in environments where multiple users share the same Jenkins instance. Organizations may face compliance violations under standards such as iso 27001 and pci dss due to the exposure of session identifiers.
Mitigation strategies for this vulnerability require immediate patching of affected Jenkins installations to versions 2.218 or later for standard releases and 2.204.1 for LTS versions. Administrators should also implement network-level restrictions to limit access to the whoAmI diagnostic page to authorized personnel only. Additional defensive measures include enabling proper access controls and implementing web application firewalls to monitor and block suspicious requests to diagnostic endpoints. Organizations should conduct regular security audits to identify similar exposure issues within their Jenkins configurations and ensure that all diagnostic functionality properly sanitizes output data. The remediation process should also include reviewing and updating user access controls to prevent unauthorized access to sensitive system information. This vulnerability demonstrates the importance of proper session management and output validation in web applications, aligning with ATT&CK technique T1548.001 for privilege escalation through session hijacking and T1078.004 for valid accounts exploitation.