CVE-2008-5860 in Constructr
Summary
by MITRE
Directory traversal vulnerability in backend/template.php in Constructr CMS 3.02.5 and earlier, when register_globals is enabled and magic_quotes_gpc is disabled, allows remote attackers to create or read arbitrary files via directory traversal sequences in the edit_file parameter.
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Analysis
by VulDB Data Team • 11/20/2024
The vulnerability described in CVE-2008-5860 represents a critical directory traversal flaw within the Constructr CMS 3.02.5 and earlier versions. This weakness specifically affects the backend/template.php component and exploits a combination of server configuration settings that create an exploitable condition. The vulnerability arises when the PHP configuration parameter register_globals is enabled and magic_quotes_gpc is disabled, creating an environment where user input is directly injected into the global namespace without proper sanitization. This configuration combination fundamentally undermines the security boundaries that would normally protect against malicious input manipulation.
The technical exploitation of this vulnerability occurs through manipulation of the edit_file parameter within the backend/template.php script. When an attacker crafts malicious directory traversal sequences such as ../../ or ../../../ within this parameter, the application fails to properly validate or sanitize the input before using it in file operations. This allows the attacker to bypass normal file access controls and potentially create or read arbitrary files on the server filesystem. The vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw enables attackers to navigate beyond the intended directory structure and access sensitive files that should remain protected.
The operational impact of this vulnerability is severe and multifaceted, particularly when considering the attack surface of content management systems. An attacker could potentially access sensitive configuration files, database credentials, user data, or even system files that contain critical information. The ability to create arbitrary files opens the door to code injection scenarios where malicious payloads could be written to the filesystem and subsequently executed. This vulnerability aligns with several ATT&CK techniques including T1059 for command and scripting interpreter and T1566 for credential access through exploitation of vulnerabilities. The attack vector is particularly dangerous because it requires minimal privileges to exploit, as the vulnerability exists in the backend administrative interface.
Mitigation strategies for this vulnerability must address both the immediate security flaw and the underlying server configuration issues. The primary recommendation involves disabling register_globals in PHP configuration, as this setting directly enables the vulnerability by automatically creating global variables from user input. Additionally, the magic_quotes_gpc should be enabled to provide basic input sanitization, though this alone is insufficient for complete protection. Application-level fixes should include implementing proper input validation and sanitization techniques, such as using realpath() and basename() functions to normalize file paths, and implementing strict whitelisting of allowed file operations. Organizations should also consider implementing web application firewalls to detect and block suspicious directory traversal patterns, and regularly audit their server configurations to ensure that potentially dangerous PHP settings remain disabled. The vulnerability demonstrates the critical importance of proper input validation and the dangers of legacy PHP configurations that were once considered acceptable but now pose significant security risks.