CVE-2009-4137 in Piwik
Summary
by MITRE
The loadContentFromCookie function in core/Cookie.php in Piwik before 0.5 does not validate strings obtained from cookies before calling the unserialize function, which allows remote attackers to execute arbitrary code or upload arbitrary files via vectors related to the __destruct function in the Piwik_Config class; php://filter URIs; the __destruct functions in Zend Framework, as demonstrated by the Zend_Log destructor; the shutdown functions in Zend Framework, as demonstrated by the Zend_Log_Writer_Mail class; the render function in the Piwik_View class; Smarty templates; and the _eval function in Smarty.
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Analysis
by VulDB Data Team • 08/30/2021
The vulnerability described in CVE-2009-4137 represents a critical remote code execution flaw in the Piwik analytics platform version 0.5 and earlier. This issue stems from improper input validation within the loadContentFromCookie function located in core/Cookie.php, where user-supplied cookie data is directly passed to the unserialize function without adequate sanitization or validation. The vulnerability falls under the category of deserialization attacks, specifically aligning with CWE-502 which addresses unsafe deserialization of untrusted data. The flaw enables attackers to manipulate serialized objects stored in cookies, potentially executing arbitrary code on the target system.
The technical exploitation of this vulnerability leverages the PHP unserialize mechanism to trigger malicious code execution through various attack vectors. Attackers can craft specially formatted cookie data that, when deserialized, invokes the __destruct method of the Piwik_Config class or other vulnerable components. This particular attack chain demonstrates the dangerous nature of PHP object injection when untrusted data flows into the unserialize function. The vulnerability extends beyond simple code execution to include arbitrary file upload capabilities, making it particularly dangerous for web applications. The attack surface includes multiple components within the Piwik framework and its dependencies such as the Zend Framework and Smarty templating engine, where destructor methods and rendering functions can be manipulated to achieve remote code execution.
The operational impact of this vulnerability is severe, as it allows remote attackers to gain complete control over affected systems without requiring authentication. Once exploited, attackers can execute arbitrary commands, upload malicious files, and potentially escalate privileges within the compromised environment. The vulnerability affects not only the Piwik application itself but also its underlying dependencies, making it a widespread concern for systems utilizing these components. The attack can be executed through simple cookie manipulation, requiring no special privileges or complex exploitation techniques, which significantly increases the risk and attack surface. Organizations running vulnerable versions of Piwik face potential data breaches, system compromise, and complete loss of control over their analytics infrastructure.
Mitigation strategies for CVE-2009-4137 require immediate patching of the Piwik application to version 0.5 or later, where the vulnerability has been addressed. System administrators should implement proper input validation and sanitization for all cookie data, ensuring that serialized content is properly validated before deserialization occurs. The recommended approach involves implementing strict type checking and using whitelisting mechanisms to prevent unauthorized object instantiation. Additionally, organizations should consider implementing web application firewalls and monitoring for suspicious cookie patterns that might indicate exploitation attempts. Network segmentation and access controls can help limit the potential damage from successful exploitation. The vulnerability also highlights the importance of secure coding practices, particularly in handling untrusted data, and aligns with ATT&CK technique T1190 for exploiting vulnerabilities in web applications. Regular security audits and dependency updates are essential to prevent similar issues in the future, as the vulnerability demonstrates how seemingly minor input validation flaws can lead to complete system compromise.