CVE-2006-4191 in Extreme Message Board
Summary
by MITRE
Directory traversal vulnerability in memcp.php in XMB (Extreme Message Board) 1.9.6 and earlier allows remote attackers to include and execute arbitrary local files via directory traversal sequences in the langfilenew parameter, as demonstrated by injecting PHP sequences into an Apache HTTP Server log file, which is then included by header.php.
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Analysis
by VulDB Data Team • 07/14/2024
The vulnerability identified as CVE-2006-4191 represents a critical directory traversal flaw within the XMB (Extreme Message Board) software version 1.9.6 and earlier. This vulnerability exists in the memcp.php script which processes user input through the langfilenew parameter without adequate validation or sanitization. The flaw enables remote attackers to manipulate file inclusion mechanisms by exploiting directory traversal sequences such as ../ or ..\, allowing them to access arbitrary local files on the server. The vulnerability is particularly dangerous because it can be exploited to execute arbitrary code by injecting PHP sequences into log files that are subsequently included by other scripts, creating a chain of execution that can compromise the entire system.
The technical implementation of this vulnerability stems from improper input validation and insecure file handling practices within the memcp.php script. When the langfilenew parameter is processed, the application fails to properly sanitize user-supplied input, allowing directory traversal sequences to pass through unchanged. This creates an opportunity for attackers to navigate the file system and access sensitive files that should remain protected. The specific exploitation technique involves injecting PHP code into Apache HTTP Server log files, which are then included by header.php through the vulnerable memcp.php script. This approach leverages the web server's logging mechanism as an attack vector, making the exploitation more stealthy and difficult to detect through traditional security monitoring.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it provides attackers with the capability to execute arbitrary code on the affected system. By leveraging the log file injection technique, attackers can achieve persistent access to the server and potentially escalate privileges to gain full administrative control. The vulnerability affects the confidentiality, integrity, and availability of the system, as unauthorized parties can read sensitive data, modify system files, and disrupt normal operations. The attack surface is particularly concerning because it can be exploited remotely without requiring authentication, making it accessible to anyone who can interact with the vulnerable web application.
This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The flaw also maps to several ATT&CK techniques including T1059.007 for command and script injection, T1566.001 for spearphishing with attachments, and T1078 for valid accounts. The attack chain typically involves initial reconnaissance to identify the vulnerable application, followed by crafting malicious payloads that exploit the directory traversal mechanism. Security practitioners should consider this vulnerability as part of a broader attack surface assessment, particularly focusing on web applications that handle user input for file operations. Organizations should implement proper input validation, use whitelisting approaches for file access, and regularly update their software to address known vulnerabilities. The remediation strategy involves patching the affected XMB version or implementing proper parameter validation and sanitization to prevent directory traversal sequences from being processed as legitimate file paths.