CVE-2016-3726 in Jenkins
Summary
by MITRE
Multiple open redirect vulnerabilities in CloudBees Jenkins before 2.3 and LTS before 1.651.2 allow remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via unspecified vectors related to "scheme-relative" URLs.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-3726 represents a critical open redirect flaw affecting CloudBees Jenkins versions prior to 2.3 and LTS versions before 1.651.2. This security weakness stems from improper validation of URL schemes in the application's redirect handling mechanisms, creating a pathway for malicious actors to manipulate user navigation. The vulnerability specifically targets scheme-relative URLs, which are web addresses that begin with double forward slashes and rely on the current protocol context for completion. These URLs can be exploited to bypass normal security checks and redirect users to attacker-controlled domains without proper validation.
The technical implementation of this vulnerability allows attackers to craft malicious URLs that appear legitimate within the Jenkins interface while silently redirecting users to phishing sites or malicious domains. When Jenkins processes these scheme-relative URLs, it fails to properly validate the target domain against a whitelist or perform adequate security checks. This flaw enables attackers to construct URLs that exploit the trust relationship between the Jenkins application and its users, particularly when Jenkins is accessed through web browsers where the redirect mechanism operates. The vulnerability exists in the application's URL parsing and validation logic, where scheme-relative URLs are not properly sanitized or verified before being used in redirect operations.
The operational impact of this vulnerability extends beyond simple phishing attacks, as it can facilitate more sophisticated social engineering campaigns and credential theft operations. Users who navigate to compromised Jenkins pages may be unknowingly redirected to malicious sites that mimic legitimate Jenkins interfaces or corporate authentication portals. This creates significant risk for organizations relying on Jenkins for continuous integration and deployment processes, as attackers can exploit the vulnerability to capture user credentials, inject malicious code, or redirect users to sites hosting malware. The vulnerability is particularly dangerous in enterprise environments where Jenkins is used for automated build processes and access to sensitive systems.
Organizations affected by this vulnerability should immediately upgrade to patched versions of Jenkins, specifically version 2.3 or LTS version 1.651.2, which contain fixes for the URL validation logic. Security teams should implement network-level monitoring to detect suspicious redirect patterns and consider implementing additional web application firewalls or security controls to prevent exploitation. The vulnerability maps to CWE-601 Open Redirect vulnerability category, which is classified under the broader weakness of insecure direct object references. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1566 Phishing and T1071.004 Application Layer Protocol HTTP, as it enables attackers to manipulate user sessions through malicious web redirects. Organizations should also review their Jenkins configurations to ensure proper URL validation is enforced and consider implementing additional security measures such as content security policies and strict redirect validation rules to prevent similar vulnerabilities from occurring in other applications within their infrastructure.