CVE-2017-6080 in Zammad
Summary
by MITRE
An issue was discovered in Zammad before 1.0.4, 1.1.x before 1.1.3, and 1.2.x before 1.2.1, caused by lack of a protection mechanism involving HTTP Access-Control headers. To exploit the vulnerability, an attacker can send cross-domain requests directly to the REST API for users with a valid session cookie and receive the result.
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Analysis
by VulDB Data Team • 09/06/2020
The vulnerability identified as CVE-2017-6080 represents a critical security flaw in the Zammad helpdesk system affecting multiple version ranges including pre-1.0.4, pre-1.1.3, and pre-1.2.1 releases. This weakness stems from the absence of proper HTTP Access-Control headers that should govern cross-origin resource sharing behaviors. The flaw fundamentally compromises the application's ability to enforce proper access controls between different domains, creating an avenue for unauthorized data access through malicious cross-domain requests.
The technical implementation of this vulnerability exploits the lack of CORS (Cross-Origin Resource Sharing) protection mechanisms within the Zammad REST API endpoints. When a legitimate user maintains an active session cookie, an attacker can craft malicious requests that target the application's API directly from an external domain. This attack vector leverages the fact that the system fails to implement proper origin validation through Access-Control-Allow-Origin headers, allowing unauthorized domains to make requests to the protected API endpoints. The vulnerability specifically affects the REST API functionality where session-based authentication should prevent unauthorized access but fails to enforce cross-domain restrictions.
From an operational perspective, this vulnerability creates significant risk for organizations using affected Zammad versions as it enables attackers to bypass normal access controls through cross-domain requests. The attack requires minimal prerequisites since it only needs a valid session cookie from an authenticated user, making it particularly dangerous in environments where session management is not properly secured. The impact extends beyond simple data theft to potentially enable privilege escalation attacks, as the attacker can access sensitive user information and potentially manipulate system resources through the exposed API endpoints. This flaw directly violates the principle of least privilege and undermines the application's security model.
The vulnerability maps directly to CWE-346, which addresses "Origin Validation Error" in web applications, and aligns with ATT&CK technique T1071.004 for application layer protocol manipulation. Organizations should immediately implement proper CORS header configurations including Access-Control-Allow-Origin, Access-Control-Allow-Methods, and Access-Control-Allow-Headers to prevent unauthorized cross-domain access. The recommended mitigations include enforcing strict origin validation, implementing additional authentication checks for API endpoints, and ensuring that session cookies are properly secured with HttpOnly and Secure flags. Patching to versions 1.0.4, 1.1.3, or 1.2.1 respectively resolves the underlying implementation flaw by introducing proper CORS protection mechanisms that validate request origins before processing API requests.