CVE-2008-3415 in CMScout
Summary
by MITRE
Directory traversal vulnerability in common.php in CMScout 2.05, when .htaccess is not supported, allows remote attackers to include and execute arbitrary local files via directory traversal sequences in the bit parameter, as demonstrated by an upload to avatar/ of a .jpg file containing PHP sequences.
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Analysis
by VulDB Data Team • 11/02/2024
The vulnerability identified as CVE-2008-3415 represents a critical directory traversal flaw in CMScout 2.05 content management system that fundamentally compromises the application's security boundaries. This weakness specifically affects systems where .htaccess configuration files are not supported or functional, creating an environment where malicious actors can exploit the application's file handling mechanisms. The vulnerability manifests through the bit parameter in the common.php script, which fails to properly validate or sanitize user input before processing file operations. When an attacker crafts malicious directory traversal sequences within this parameter, they can manipulate the application's file inclusion logic to access arbitrary local files on the server. The attack vector becomes particularly dangerous when combined with the ability to upload files to the avatar/ directory, as demonstrated by the use of .jpg files containing embedded PHP code. This technique allows attackers to bypass normal file upload restrictions and execute arbitrary code on the target system.
The technical implementation of this vulnerability aligns with CWE-22, which categorizes directory traversal attacks as a fundamental weakness in input validation. The flaw occurs because the application does not properly filter or sanitize the bit parameter, allowing attackers to inject sequences such as ../ or ../../../ that traverse the file system hierarchy. When combined with the upload functionality to the avatar directory, this creates a complete attack chain where malicious code can be uploaded as an image file but executed as PHP code. The vulnerability essentially removes the application's ability to distinguish between legitimate file operations and malicious traversal attempts, enabling attackers to access sensitive files including configuration files, database credentials, or other system resources that should remain protected. This type of vulnerability falls under the ATT&CK technique T1566.001 which describes the use of malicious file uploads to gain initial access or execute code on target systems.
The operational impact of CVE-2008-3415 extends far beyond simple unauthorized file access, as it provides attackers with the capability to execute arbitrary code on the compromised system. Once an attacker successfully exploits this vulnerability, they can potentially gain full control over the web server, access databases, steal sensitive information, or establish persistent backdoors. The attack's effectiveness is amplified by the fact that it does not require authentication or specialized privileges, making it particularly dangerous for publicly accessible web applications. The vulnerability's exploitation becomes even more severe when considering that modern web applications often store sensitive data in predictable locations that can be accessed through directory traversal. The ability to upload and execute PHP code through image files also makes this attack vector difficult to detect through traditional security monitoring, as the malicious code is disguised within what appears to be a legitimate file type.
Mitigation strategies for CVE-2008-3415 must address both the immediate vulnerability and broader security practices within the application architecture. The most effective immediate solution involves implementing proper input validation and sanitization for all parameters that influence file operations, particularly ensuring that directory traversal sequences are rejected or properly encoded. Applications should enforce strict file type validation and avoid allowing execution of PHP code within upload directories, even when files appear to be images. The implementation of a whitelist-based approach for file operations, where only explicitly allowed paths and file extensions are permitted, provides a robust defense against such attacks. Organizations should also implement proper access controls and file permissions that prevent unauthorized access to sensitive system directories, while ensuring that .htaccess configurations are properly implemented to restrict access to sensitive files. Additionally, regular security audits and code reviews should be conducted to identify similar vulnerabilities in other application components, as directory traversal flaws often occur in multiple locations within complex applications. The remediation process should also include updating to supported versions of CMScout or migrating to more secure content management systems that have addressed these fundamental security weaknesses.