CVE-2015-5687 in Anchor
Summary
by MITRE
system/session/drivers/cookie.php in Anchor CMS 0.9.x allows remote attackers to conduct PHP object injection attacks and execute arbitrary PHP code via a crafted serialized object in a cookie.
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Analysis
by VulDB Data Team • 06/20/2022
The vulnerability identified as CVE-2015-5687 resides within the Anchor CMS 0.9.x content management system, specifically in the system/session/drivers/cookie.php file. This issue represents a critical security flaw that enables remote attackers to perform PHP object injection attacks through manipulation of cookie data. The vulnerability stems from the application's improper handling of serialized PHP objects within HTTP cookies, creating an avenue for arbitrary code execution. The affected version range indicates this flaw was present in the 0.9.x series, suggesting it was a significant oversight in the session management component that processed user authentication and session data through cookie mechanisms.
The technical implementation of this vulnerability involves the deserialization of user-controllable data without proper sanitization or validation. When Anchor CMS processes cookies containing serialized PHP objects, it fails to verify the integrity or legitimacy of these objects before attempting to unserialize them. This creates a scenario where an attacker can craft a malicious serialized object that, when processed by the application, executes arbitrary PHP code on the server. The attack vector is particularly dangerous because it requires no authentication and can be executed through standard web browser interactions via cookie manipulation. This flaw aligns with CWE-502, which describes "Deserialization of Untrusted Data" as a critical weakness that can lead to remote code execution when objects are unserialized without proper validation.
The operational impact of CVE-2015-5687 extends beyond simple code execution, as it provides attackers with complete control over the affected web server. Successful exploitation allows adversaries to upload malicious files, execute system commands, access sensitive data, and potentially establish persistent backdoors within the CMS environment. The vulnerability affects the entire session management infrastructure, making it possible for attackers to hijack user sessions, impersonate legitimate users, and gain unauthorized access to administrative functions. This type of vulnerability is particularly concerning in web applications where session data is stored in cookies, as it directly impacts the security of user authentication mechanisms and can compromise the integrity of the entire application stack. The attack surface is broad since cookies are routinely used for session management across web applications, making this a widespread concern.
Mitigation strategies for CVE-2015-5687 require immediate action to address the core deserialization vulnerability. The primary recommendation involves upgrading to a patched version of Anchor CMS that properly validates and sanitizes serialized data before deserialization. Organizations should implement input validation measures that prevent malicious serialized objects from being processed, including the use of cryptographic signatures or checksums to verify cookie integrity. Security headers such as HttpOnly and Secure flags should be implemented for session cookies to prevent client-side script access and ensure encrypted transmission. Additionally, implementing proper error handling that does not expose internal application details can help prevent information leakage during exploitation attempts. The mitigation approach aligns with ATT&CK technique T1190, which focuses on exploiting vulnerabilities in application code, and emphasizes the importance of secure coding practices that prevent deserialization attacks. Organizations should also consider implementing web application firewalls that can detect and block suspicious cookie patterns, though this represents a secondary defense mechanism rather than a primary fix. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other components of the application stack.