CVE-2018-8718 in Mailer Plugin
Summary
by MITRE
Cross-site request forgery (CSRF) vulnerability in the Mailer Plugin 1.20 for Jenkins 2.111 allows remote authenticated users to send unauthorized mail as an arbitrary user via a /descriptorByName/hudson.tasks.Mailer/sendTestMail request.
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Analysis
by VulDB Data Team • 06/18/2024
The CVE-2018-8718 vulnerability represents a critical cross-site request forgery flaw within the Mailer Plugin for Jenkins version 1.20, specifically affecting Jenkins 2.111 installations. This vulnerability exposes organizations to unauthorized email sending capabilities through a carefully crafted malicious request that exploits the plugin's lack of proper authentication verification mechanisms. The flaw exists in the /descriptorByName/hudson.tasks.Mailer/sendTestMail endpoint which should only accept authenticated requests from legitimate administrators but instead permits unauthorized users to execute mail sending operations on behalf of arbitrary users within the system.
The technical implementation of this vulnerability stems from insufficient input validation and authentication checks within the Jenkins Mailer Plugin's REST endpoint handling. When an authenticated user accesses the vulnerable endpoint without proper CSRF token verification, the system processes the request and executes the mail sending operation without confirming that the request originates from a legitimate administrative source. This represents a classic CSRF attack vector where malicious actors can craft specially formatted requests that leverage the victim's existing authenticated session to perform unauthorized actions. The vulnerability specifically affects the test mail functionality that should only be accessible to authorized administrators but can be triggered by any authenticated user within the Jenkins environment.
The operational impact of this vulnerability extends beyond simple unauthorized email sending as it creates potential for abuse in various attack scenarios including spam distribution, phishing campaigns, and social engineering attacks. An attacker with minimal privileges within the Jenkins environment can exploit this flaw to send malicious emails that appear to originate from legitimate system administrators, potentially compromising user trust and enabling further attacks. The vulnerability is particularly concerning in enterprise environments where Jenkins serves as a central automation platform and administrators may have elevated privileges that make the unauthorized email sending capability more dangerous. This flaw undermines the principle of least privilege and creates opportunities for attackers to establish persistence or conduct reconnaissance activities through email-based communication channels.
Organizations should immediately implement mitigations including updating to Jenkins Mailer Plugin versions that address this vulnerability, typically versions 1.21 or later, and implementing additional security controls such as enabling CSRF protection mechanisms within Jenkins configuration. The vulnerability aligns with CWE-352 which specifically addresses Cross-Site Request Forgery weaknesses in web applications, and maps to ATT&CK technique T1059.001 for Command and Scripting Interpreter where attackers might leverage compromised Jenkins systems to send malicious emails. Security teams should also consider implementing network-level restrictions on the vulnerable endpoint, enabling two-factor authentication for administrative accounts, and conducting regular security assessments of Jenkins plugins to identify similar vulnerabilities. Additionally, organizations should review their Jenkins configurations to ensure proper access controls are in place and that all administrative endpoints require appropriate authentication tokens and verification mechanisms to prevent unauthorized access and execution of privileged operations.