CVE-2008-6669 in nweb2fax
Summary
by MITRE
viewrq.php in nweb2fax 0.2.7 and earlier allows remote attackers to execute arbitrary code via shell metacharacters in the var_filename parameter in a (1) tif or (2) pdf format action.
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Analysis
by VulDB Data Team • 10/29/2024
The vulnerability identified as CVE-2008-6669 affects nweb2fax version 0.2.7 and earlier, representing a critical remote code execution flaw in the viewrq.php script. This vulnerability stems from inadequate input validation and sanitization within the web application's file handling mechanisms, specifically when processing the var_filename parameter. The flaw exists in the context of fax processing functionality where the application accepts user-supplied filenames for generating tif or pdf format output files. The vulnerability is particularly dangerous because it allows remote attackers to inject shell metacharacters directly into the filename parameter, which then gets processed without proper sanitization, creating a direct pathway for arbitrary code execution on the affected system. This type of vulnerability falls under the CWE-77 category, which specifically addresses the execution of code via command injection flaws, and aligns with ATT&CK technique T1190 for exploitation of remote services through command injection.
The technical implementation of this vulnerability occurs when an attacker submits a malicious filename containing shell metacharacters such as semicolons, ampersands, or other command separators through the var_filename parameter. When the application processes this parameter in the viewrq.php script, it directly incorporates the user input into system commands without proper escaping or validation, allowing the attacker to chain commands and execute arbitrary code with the privileges of the web server process. The vulnerability is particularly severe because it affects both tif and pdf format actions, expanding the attack surface and providing multiple vectors for exploitation. The flaw demonstrates poor input handling practices and lacks proper sanitization of user-supplied data before it is used in system command execution contexts, which is a fundamental security principle that should be enforced throughout all application layers.
The operational impact of this vulnerability is substantial as it provides attackers with complete control over the affected system, potentially allowing them to establish persistent backdoors, escalate privileges, access sensitive data, or use the compromised system as a launch point for further attacks within the network. The remote nature of the exploit means that attackers do not require physical access or prior authentication to exploit the vulnerability, making it particularly dangerous for publicly accessible web applications. Organizations running affected versions of nweb2fax are at risk of complete system compromise, data breaches, and potential lateral movement within their network infrastructure. The vulnerability also creates a persistent threat as the malicious code execution can be maintained across system restarts, and the compromised system may be used for hosting additional malicious payloads or as a command and control server for other attacks. The flaw demonstrates a critical gap in the application's security architecture where input validation is insufficient to prevent command injection attacks, which is a fundamental requirement for web applications handling user input in system contexts.
Mitigation strategies for CVE-2008-6669 should prioritize immediate patching of the affected nweb2fax versions to the latest available release that contains proper input validation and sanitization. Organizations should implement proper parameter validation and sanitization mechanisms that prevent shell metacharacters from being processed in user-supplied filenames, utilizing allow-list validation approaches rather than deny-list methods. The application should employ proper input escaping techniques when incorporating user data into system commands, and all user-supplied parameters should undergo rigorous validation before being processed. Network segmentation and firewall rules should be implemented to limit access to the affected web application, while monitoring systems should be deployed to detect unusual command execution patterns or suspicious file processing activities. Additionally, organizations should conduct comprehensive security assessments of their web applications to identify similar command injection vulnerabilities, and implement secure coding practices that emphasize input validation, proper error handling, and secure system command execution procedures. The remediation process should also include regular security updates, vulnerability scanning, and maintaining up-to-date security patches to prevent similar issues from arising in the future.