CVE-2008-4712 in LnBlog
Summary
by MITRE
Directory traversal vulnerability in pages/showblog.php in LnBlog 0.9.0 and earlier, when magic_quotes_gpc is disabled, allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the plugin parameter.
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Analysis
by VulDB Data Team • 11/05/2024
The vulnerability described in CVE-2008-4712 represents a critical directory traversal flaw within the LnBlog 0.9.0 content management system, specifically affecting the pages/showblog.php script. This weakness occurs when the PHP configuration parameter magic_quotes_gpc is disabled, creating an exploitable condition that enables remote attackers to manipulate file inclusion mechanisms. The vulnerability stems from insufficient input validation and sanitization of the plugin parameter, which directly influences how the application processes file paths during dynamic content loading operations.
The technical implementation of this flaw involves the manipulation of the plugin parameter through directory traversal sequences using the .. (dot dot) notation. When magic_quotes_gpc is disabled, the application fails to properly sanitize user-supplied input before using it in file inclusion operations. Attackers can exploit this by crafting malicious URLs that contain directory traversal sequences, allowing them to navigate outside the intended directory structure and access arbitrary local files on the server. This type of vulnerability falls under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to execute arbitrary code on the affected server. Successful exploitation could result in complete system compromise, data theft, or unauthorized access to sensitive server resources. The vulnerability is particularly dangerous because it leverages the fundamental file inclusion mechanism of the application, potentially allowing attackers to access configuration files, database credentials, or other sensitive information stored on the server. This weakness directly aligns with ATT&CK technique T1505.003, which covers server-side include attacks, and represents a classic example of how insufficient input validation can lead to remote code execution through file inclusion vulnerabilities.
Mitigation strategies for this vulnerability must address both the immediate security flaw and the underlying configuration issues that enable exploitation. The primary recommendation involves implementing proper input validation and sanitization for all user-supplied parameters, particularly those used in file inclusion operations. The application should employ strict path validation that prevents directory traversal sequences from being processed, regardless of the magic_quotes_gpc setting. Additionally, administrators should ensure that magic_quotes_gpc is properly configured or implement alternative input sanitization measures. The system should also enforce proper file access controls and implement a principle of least privilege for file operations. Organizations should consider implementing web application firewalls to detect and block suspicious traversal patterns, while also ensuring that all affected systems are updated to newer versions of LnBlog that address this vulnerability. Regular security audits and input validation testing should be conducted to prevent similar issues from emerging in other components of the application stack.