CVE-2004-1404 in Attachment Mod
Summary
by MITRE
Attachment Mod 2.3.10 module for phpBB, when used with Apache mod_mime, does not properly handle files with multiple file extensions, such as .php.rar, which allows remote attackers to upload and execute arbitrary code.
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Analysis
by VulDB Data Team • 06/23/2018
The vulnerability identified as CVE-2004-1404 represents a critical security flaw in the Attachment Mod 2.3.10 module for phpBB platforms, specifically when integrated with Apache mod_mime functionality. This issue stems from insufficient validation mechanisms that fail to properly process files containing multiple extensions, creating a pathway for malicious code execution through unauthorized file uploads. The flaw exploits a fundamental weakness in how the system interprets file types and extensions, particularly when dealing with complex filename structures that combine multiple dots and extensions.
The technical root cause of this vulnerability lies in the improper handling of file extensions within the attachment processing module. When a file with multiple extensions such as .php.rar is uploaded, the system fails to correctly identify the actual file type based on content inspection rather than relying solely on extension-based detection. Apache mod_mime, which is responsible for determining file types based on their content and extensions, does not adequately validate these multi-extension filenames, allowing the system to treat the file as a legitimate attachment while potentially executing malicious code. This behavior creates a scenario where the server processes the file according to the last extension in the sequence rather than examining the actual file content, opening the door for attackers to bypass security measures.
The operational impact of this vulnerability extends beyond simple code execution, as it allows remote attackers to gain unauthorized access to the affected system. Attackers can upload malicious files that appear to be harmless attachments but contain executable code disguised as legitimate extensions. This capability enables various attack vectors including web shell deployment, privilege escalation, data exfiltration, and potential system compromise. The vulnerability is particularly dangerous in environments where phpBB forums are publicly accessible and where administrators may not have proper security monitoring in place to detect unauthorized file uploads.
The security implications of CVE-2004-1404 align with CWE-434, which addresses the improper restriction of file uploads, and can be mapped to ATT&CK technique T1190 for "Exploit Public-Facing Application" and T1059 for "Command and Scripting Interpreter." The vulnerability demonstrates how improper input validation and file type handling can lead to arbitrary code execution, making it a prime target for automated exploitation tools and manual attack campaigns. Organizations running affected phpBB installations are particularly vulnerable as the flaw exists in the core attachment handling logic, making it difficult to patch without comprehensive system updates.
Mitigation strategies for this vulnerability require immediate attention and include implementing proper file type validation based on content rather than extensions, disabling file uploads for sensitive user groups, and deploying web application firewalls to monitor and block suspicious file upload patterns. System administrators should also consider implementing strict file extension whitelisting, enabling MIME type checking, and conducting regular security audits of attachment handling modules. The most effective long-term solution involves updating to patched versions of phpBB and the Attachment Mod, as the vulnerability was addressed in subsequent releases that properly validate multi-extension files and implement more robust content inspection mechanisms.