CVE-2011-4451 in WikkaWiki
Summary
by MITRE
** DISPUTED ** libs/Wakka.class.php in WikkaWiki 1.3.1 and 1.3.2, when the spam_logging option is enabled, allows remote attackers to write arbitrary PHP code to the spamlog_path file via the User-Agent HTTP header in an addcomment request. NOTE: the vendor disputes this issue because the rendering of the spamlog_path file never uses the PHP interpreter.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2011-4451 affects WikkaWiki versions 1.3.1 and 1.3.2, specifically when the spam_logging feature is enabled. This issue resides within the libs/Wakka.class.php file and represents a potential code injection vector that could be exploited by remote attackers. The vulnerability manifests through the manipulation of the User-Agent HTTP header during an addcomment request, allowing malicious actors to write arbitrary PHP code into the spamlog_path file. This presents a significant security risk as it could enable unauthorized code execution on the affected web server, potentially leading to complete system compromise.
The technical flaw stems from improper input validation and sanitization within the spam logging mechanism. When the spam_logging option is enabled, the application creates a spamlog_path file to store information about spam attempts. However, the application fails to properly sanitize the User-Agent header value before writing it to this file. This lack of input sanitization creates an opportunity for attackers to inject malicious PHP code that gets stored in the log file, which could then be executed under certain conditions. The vulnerability operates at the application level and demonstrates poor security practices in handling user-supplied data, specifically violating CWE-20 standards for improper input validation. The issue is particularly concerning because it leverages HTTP headers as attack vectors, which are commonly used in web-based attacks and often bypass traditional network security measures.
From an operational impact perspective, this vulnerability could allow attackers to execute arbitrary code on the affected WikkaWiki installation, potentially leading to full system compromise. The ability to write PHP code to a log file creates a persistent backdoor opportunity, as the attacker can inject malicious code that remains dormant until executed. This could result in data theft, service disruption, unauthorized access to sensitive information, and potential lateral movement within the network. The vendor's position that the rendering of the spamlog_path file never uses the PHP interpreter suggests that the immediate execution path may not be straightforward, but the vulnerability still represents a code injection risk that could be exploited through other vectors or in combination with other vulnerabilities. The impact extends beyond simple code execution to include potential privilege escalation and persistent access to the compromised system.
The suggested mitigations for this vulnerability include immediate patching of the WikkaWiki installation to a version that addresses this issue, as well as implementing proper input validation and sanitization measures. Organizations should disable the spam_logging feature if it is not essential for their operations, and ensure that all user-supplied data is properly validated and sanitized before being written to any files. Network-level protections such as web application firewalls and intrusion prevention systems can provide additional layers of defense. The vulnerability also highlights the importance of secure coding practices and proper input handling, particularly when dealing with user-supplied data that may be stored and later processed. Security monitoring should include checks for unusual file modifications in log directories, and regular security audits should verify that applications properly handle user input to prevent similar issues. This vulnerability underscores the critical need for defense in depth strategies and proper security testing of web applications before deployment.