CVE-2001-1140 in Badblue
Summary
by MITRE
BadBlue Personal Edition v1.02 beta allows remote attackers to read source code for executable programs by appending a %00 (null byte) to the request.
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Analysis
by VulDB Data Team • 09/29/2025
The vulnerability identified as CVE-2001-1140 affects BadBlue Personal Edition version 1.02 beta, representing a classic null byte injection flaw that enables unauthorized remote access to sensitive source code files. This vulnerability resides in the web server's handling of file requests and demonstrates a fundamental lack of proper input validation and sanitization. The specific exploitation technique involves appending a null byte character %00 to HTTP requests, which exploits improper string termination handling in the application's file access routines. This particular version of BadBlue failed to adequately validate or sanitize user-supplied input before processing file requests, creating an avenue for attackers to bypass normal access controls and retrieve executable source code.
The technical implementation of this vulnerability stems from the application's failure to properly handle null byte characters in file paths, a common weakness in applications that do not perform adequate input validation. When the null byte is appended to a request, it effectively truncates the file path string, allowing attackers to access files that should otherwise be restricted or protected. This behavior aligns with CWE-170, which addresses improper null termination handling in string operations, and demonstrates how inadequate input validation can lead to privilege escalation and information disclosure. The vulnerability operates at the application layer and requires no special privileges to exploit, making it particularly dangerous as it can be leveraged by any remote attacker with basic network access to the affected server.
The operational impact of this vulnerability extends beyond simple information disclosure, as access to executable source code provides attackers with detailed insights into the application's internal structure, potential security weaknesses, and implementation details. This intelligence can be used to develop more sophisticated attacks targeting other components of the system or to craft targeted exploits against known vulnerabilities within the application's codebase. The exposure of source code can reveal hardcoded credentials, database connection strings, and other sensitive information that might not be apparent through normal reconnaissance activities. From an attacker's perspective, this vulnerability maps to techniques described in the ATT&CK framework under T1566 for credential access and T1083 for file and directory discovery, as it enables unauthorized access to critical system information.
Mitigation strategies for CVE-2001-1140 should focus on implementing proper input validation and sanitization measures that prevent null byte injection attacks. Organizations should immediately update to patched versions of BadBlue Personal Edition or migrate to more secure web server solutions that properly handle input validation. The fix should include implementing strict validation of file paths, rejecting requests containing null bytes or other potentially malicious characters, and ensuring proper string handling routines that prevent null termination issues. Additionally, implementing web application firewalls and input filtering mechanisms can provide additional protection layers against similar attacks. Regular security audits and code reviews should be conducted to identify and remediate similar vulnerabilities in other applications, as this type of flaw demonstrates the critical importance of proper input validation in preventing unauthorized access to sensitive system information.