CVE-2012-3527 in TYPO3
Summary
by MITRE
view_help.php in the backend help system in TYPO3 4.5.x before 4.5.19, 4.6.x before 4.6.12 and 4.7.x before 4.7.4 allows remote authenticated backend users to unserialize arbitrary objects and possibly execute arbitrary PHP code via an unspecified parameter, related to a "missing signature (HMAC)."
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Analysis
by VulDB Data Team • 03/27/2021
The vulnerability CVE-2012-3527 represents a critical security flaw in the TYPO3 content management system that affects multiple versions including 4.5.x before 4.5.19, 4.6.x before 4.6.12, and 4.7.x before 4.7.4. This issue resides within the backend help system's view_help.php file and specifically targets authenticated backend users who possess administrative privileges. The vulnerability stems from a missing signature validation mechanism that should have been implemented through HMAC (Hash-based Message Authentication Code) to ensure the integrity and authenticity of data being processed. This weakness allows attackers who have gained access to legitimate backend accounts to exploit a deserialization vulnerability that can lead to arbitrary code execution on the server.
The technical flaw manifests when an authenticated user accesses the help system and manipulates an unspecified parameter within the view_help.php script. The system fails to properly validate the integrity of the serialized data being passed through this parameter, creating an opportunity for attackers to inject malicious serialized objects. When the system processes these objects, it performs an unserialize operation without adequate input sanitization or signature verification, which enables the execution of arbitrary PHP code on the target server. This type of vulnerability is classified as a deserialization vulnerability and falls under CWE-502, which specifically addresses the deserialization of untrusted data. The attack vector requires only authenticated access to the TYPO3 backend, making it particularly dangerous as it can be exploited by insiders or compromised accounts.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected TYPO3 versions. Attackers can leverage this weakness to execute arbitrary commands on the web server, potentially leading to complete system compromise, data theft, or service disruption. The vulnerability allows for privilege escalation and can be used to establish persistent backdoors within the system. Given that the affected versions were widely used in enterprise environments, the potential attack surface was substantial. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1566.001 for Phishing, as it enables attackers to gain a foothold through legitimate administrative access and then escalate their privileges. The lack of HMAC signature validation creates a trust boundary violation that undermines the security model of the application.
Organizations should immediately apply the patches released by TYPO3 for versions 4.5.19, 4.6.12, and 4.7.4 to address this vulnerability. The recommended mitigations include implementing proper input validation, enforcing HMAC signature verification for all serialized data, and conducting regular security audits of serialization mechanisms. Additionally, organizations should enforce strict access controls for backend systems, implement multi-factor authentication, and monitor for unusual administrative activities that might indicate exploitation attempts. Security teams should also consider implementing web application firewalls to detect and block suspicious parameter manipulation attempts, and conduct thorough vulnerability assessments to identify other potential deserialization vulnerabilities in their systems. The incident highlights the critical importance of proper input validation and signature verification in preventing deserialization attacks that can lead to complete system compromise.