CVE-2011-4449 in WikkaWiki
Summary
by MITRE
actions/files/files.php in WikkaWiki 1.3.1 and 1.3.2, when INTRANET_MODE is enabled, supports file uploads for file extensions that are typically absent from an Apache HTTP Server TypesConfig file, which makes it easier for remote attackers to execute arbitrary PHP code by placing this code in a file whose name has multiple extensions, as demonstrated by a (1) .mm or (2) .vpp file.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2011-4449 affects WikkaWiki versions 1.3.1 and 1.3.2 when operating in INTRANET_MODE, presenting a critical security flaw in the file upload handling mechanism. This vulnerability stems from an insufficient validation of file extensions during the upload process, allowing attackers to bypass security restrictions by exploiting the way the application processes multiple file extensions. The flaw specifically targets the actions/files/files.php component which manages file operations within the wiki system.
The technical implementation of this vulnerability involves the application's handling of file extensions that are not typically recognized by Apache HTTP Server's default TypesConfig file. When INTRANET_MODE is enabled, the system's file validation logic becomes inadequate, permitting uploads of files with extensions such as .mm and .vpp that would normally be restricted. These extensions can be interpreted by the web server as PHP files when they contain multiple extensions, creating a path for remote code execution. Attackers can exploit this by creating files with names containing multiple extensions, where one extension is a PHP script and another is a seemingly benign file type that the server might process.
The operational impact of this vulnerability is severe as it enables remote attackers to execute arbitrary PHP code on the affected server without authentication. This creates a complete compromise of the system, allowing attackers to gain full control over the web server, access sensitive data, modify content, and potentially use the compromised system as a launching point for further attacks within the network. The vulnerability is particularly dangerous in an intranet environment where the application might be exposed to internal users who could leverage this flaw to escalate privileges or access restricted resources.
This vulnerability maps to CWE-434, which describes "Unrestricted Upload of File with Dangerous Type," and aligns with ATT&CK technique T1190, "Exploit Public-Facing Application." The flaw demonstrates poor input validation and inadequate file type checking mechanisms that fail to properly sanitize user-supplied file names and extensions. Organizations should implement immediate mitigations including disabling INTRANET_MODE when not required, implementing strict file extension validation that rejects any extensions not explicitly whitelisted, and configuring the web server to properly handle files with multiple extensions. Additionally, regular security audits of file upload functionalities and implementing proper access controls around file operations are essential defensive measures against similar vulnerabilities in web applications.