CVE-2015-6541 in Zimbra Collaboration
Summary
by MITRE
Multiple cross-site request forgery (CSRF) vulnerabilities in the Mail interface in Zimbra Collaboration Server (ZCS) before 8.5 allow remote attackers to hijack the authentication of arbitrary users for requests that change account preferences via a SOAP request to service/soap/BatchRequest.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability identified as CVE-2015-6541 represents a critical cross-site request forgery flaw discovered in the Mail interface of Zimbra Collaboration Server versions prior to 8.5. This vulnerability resides within the web-based administrative interface and specifically targets the SOAP-based service endpoints that handle batch requests for account modifications. The flaw allows malicious actors to exploit the lack of proper authentication verification mechanisms when processing SOAP requests through the service/soap/BatchRequest endpoint, potentially enabling unauthorized actions on user accounts. The vulnerability is particularly concerning because it affects the core mail interface functionality that users interact with daily, making it a prime target for exploitation in targeted attacks.
The technical implementation of this CSRF vulnerability stems from the absence of anti-CSRF tokens or other sufficient authentication verification mechanisms within the SOAP request processing pipeline. When legitimate users access the Zimbra mail interface, their authentication session cookies are automatically included with requests, but the system fails to validate that the request originates from the authenticated user's legitimate session rather than from a malicious third party. This allows attackers to craft specially crafted web pages or email content that, when viewed by an authenticated user, automatically submits malicious SOAP requests to modify account preferences without the user's knowledge or consent. The attack vector leverages the trust relationship between the web browser and the Zimbra server, exploiting the fact that the server does not properly verify the authenticity of the request source beyond session cookies.
The operational impact of this vulnerability extends beyond simple account preference modifications, as it provides attackers with the capability to potentially hijack user sessions and perform unauthorized actions within the Zimbra environment. Attackers could leverage this vulnerability to change user passwords, modify email forwarding rules, access sensitive email content, or even escalate privileges within the system. The implications are particularly severe in enterprise environments where Zimbra serves as the primary email platform, as successful exploitation could lead to complete compromise of user mail accounts and potential lateral movement within the organization. The vulnerability affects the entire user base that has active sessions with the Zimbra interface, making it a high-impact issue that requires immediate attention from system administrators.
Security mitigation strategies for this vulnerability should focus on implementing robust anti-CSRF protection mechanisms within the Zimbra SOAP service endpoints. Organizations should upgrade to Zimbra Collaboration Server version 8.5 or later, which includes proper CSRF token validation and enhanced authentication verification processes. The implementation of proper session management, including the use of anti-CSRF tokens for all state-changing operations, should be enforced across the web interface. Network-level protections such as web application firewalls can provide additional defense-in-depth measures, while regular security auditing of web applications should be conducted to identify similar vulnerabilities. This vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses, and represents a clear violation of the principle of least privilege and proper authentication verification as outlined in various security frameworks. The attack pattern corresponds to ATT&CK technique T1566, which covers spearphishing attacks that leverage web-based vulnerabilities to gain initial access or escalate privileges within target systems.