CVE-2008-2840 in Exero
Summary
by MITRE
Multiple directory traversal vulnerabilities in Exero CMS 1.0.0 and 1.0.1 allow remote attackers to include and execute arbitrary local files via a .. (dot dot) in the theme parameter to (1) custompage.php, (2) errors/404.php, (3) members/memberslist.php, (4) members/profile.php, (5) news/fullview.php, (6) news/index.php, (7) nopermission.php, (8) usercp/avatar.php, or (9) usercp/editpassword.php in themes/Default/. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 09/26/2018
The vulnerability identified as CVE-2008-2840 represents a critical directory traversal flaw affecting Exero CMS versions 1.0.0 and 1.0.1. This security weakness stems from inadequate input validation mechanisms within the content management system's file inclusion processes. The vulnerability manifests when the theme parameter receives malicious input containing directory traversal sequences, specifically the .. (dot dot) notation, which enables attackers to manipulate file paths and access restricted system resources. The affected files span across multiple core components of the CMS including custompage.php, error handling scripts, member management pages, news viewing modules, and user control panel functions, all of which are located within the themes/Default/ directory structure.
This directory traversal vulnerability operates at the core of file inclusion mechanisms, allowing remote attackers to bypass normal access controls and execute arbitrary local files on the target system. The technical flaw resides in the improper sanitization of user-supplied input parameters, particularly the theme parameter, which directly influences file inclusion operations. When an attacker submits a malicious payload containing .. sequences, the CMS fails to properly validate or sanitize this input, leading to path traversal that can access files outside of the intended directory boundaries. The vulnerability affects multiple entry points within the application, indicating a systemic issue in input validation rather than isolated code flaws, which increases the overall attack surface and exploitability of the system.
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, potentially leading to complete system compromise. Remote exploitation allows attackers to access sensitive files including configuration data, user credentials, and application source code, which can then be used for further attacks or to establish persistent access. The vulnerability's presence in core CMS components means that successful exploitation could result in unauthorized access to user databases, modification of website content, and potential data exfiltration. Additionally, the ability to execute arbitrary local files creates opportunities for attackers to install backdoors, deploy malware, or conduct further reconnaissance activities against the compromised system.
Security practitioners should implement immediate mitigations including input validation and sanitization of all user-supplied parameters, particularly those used in file inclusion operations. The recommended approach involves implementing strict parameter validation that rejects or filters out directory traversal sequences such as .., and establishing proper access controls that limit file system access to authorized components only. Organizations should also consider implementing web application firewalls to detect and block malicious traversal attempts, while ensuring that file inclusion operations use absolute paths rather than relative paths that could be manipulated. According to CWE classification, this vulnerability maps to CWE-22 Directory Traversal, which is categorized under the broader weakness of improper input validation. The ATT&CK framework would classify this as a path traversal technique under the T1059.007 execution tactic, potentially leading to privilege escalation and lateral movement within compromised networks. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other applications, as this type of flaw remains prevalent in legacy systems and demonstrates the importance of proper input validation in preventing remote code execution attacks.