CVE-2005-1956 in File Upload Manager
Summary
by MITRE
File Upload Manager allows remote attackers to upload arbitrary files by modifying the test variable to contain a value of ~~~~~~ (six tildes), which bypasses the file extension checks.
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Analysis
by VulDB Data Team • 07/25/2017
The vulnerability described in CVE-2005-1956 represents a critical security flaw in file upload functionality that enables remote attackers to bypass essential file extension validation mechanisms. This issue resides within the File Upload Manager component where the system fails to properly validate file extensions during the upload process. The specific bypass technique involves manipulating the test variable to include exactly six tildes characters, which allows malicious files to be uploaded despite the presence of security checks designed to prevent unauthorized file uploads.
This vulnerability directly relates to CWE-434, which addresses the improper restriction of uploads of executable files, and aligns with ATT&CK technique T1195.001 focusing on content injection in web applications. The flaw demonstrates a classic case of input validation bypass where the system's security controls can be circumvented through simple manipulation of input parameters. The test variable modification to six tildes represents a clever exploitation method that exploits weaknesses in the validation logic rather than attempting to directly exploit the system's authentication or authorization mechanisms.
The operational impact of this vulnerability is significant as it allows attackers to upload arbitrary files to the target system, potentially including malicious executables, scripts, or web shells. This capability can lead to complete system compromise, unauthorized access to sensitive data, and potential lateral movement within network environments. The vulnerability is particularly dangerous because it requires minimal technical skill to exploit, making it a popular target for automated attack tools and less sophisticated threat actors who can leverage this bypass technique to gain persistent access to affected systems.
The technical implementation of this vulnerability suggests that the File Upload Manager employs a flawed validation approach that does not properly sanitize or normalize input parameters before processing file uploads. The system appears to rely on simple string matching or pattern recognition that can be easily circumvented by manipulating the test variable with six consecutive tildes. This indicates a lack of robust input validation and sanitization practices that should be implemented according to industry standards such as OWASP Top Ten and NIST cybersecurity guidelines. Organizations using this component are at risk of unauthorized code execution and data breaches.
Mitigation strategies should include implementing comprehensive file extension validation that considers multiple input parameters and does not rely solely on simple pattern matching. The system should employ proper input sanitization techniques and validate file content rather than just file extensions. Additionally, organizations should implement strict file type checks, use file content analysis to verify file integrity, and ensure that uploaded files are stored in non-executable directories. Security measures should follow the principle of least privilege and include proper access controls for file upload functionality. Regular security testing and code reviews are essential to identify similar validation bypass vulnerabilities in web applications and ensure compliance with security best practices established by frameworks such as the OWASP Application Security Verification Standard.