CVE-2002-0661 in HTTP Server
Summary
by MITRE
Directory traversal vulnerability in Apache 2.0 through 2.0.39 on Windows, OS2, and Netware allows remote attackers to read arbitrary files and execute commands via .. (dot dot) sequences containing \ (backslash) characters.
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Analysis
by VulDB Data Team • 05/26/2025
The vulnerability identified as CVE-2002-0661 represents a critical directory traversal flaw affecting Apache HTTP Server versions 2.0 through 2.0.39 on Windows, OS/2, and Netware operating systems. This vulnerability stems from improper handling of path traversal sequences containing backslash characters, creating a significant security risk that can be exploited remotely by attackers to gain unauthorized access to sensitive system resources. The flaw specifically manifests when the web server processes directory traversal sequences using backslash delimiters rather than the standard forward slash, allowing malicious actors to bypass normal file access controls and navigate to arbitrary locations within the file system.
The technical implementation of this vulnerability exploits the differences in path handling between Unix-style and Windows-style file systems within the Apache server implementation. When Apache processes requests containing .. sequences with backslash characters, the server fails to properly sanitize or normalize these path components, enabling attackers to construct malicious URLs that traverse directories beyond the intended web root. This behavior violates the fundamental security principle of proper input validation and path normalization, creating a pathway for attackers to access files that should remain protected, including configuration files, system binaries, and sensitive data repositories.
The operational impact of CVE-2002-0661 extends beyond simple file reading capabilities to encompass full command execution potential on affected systems. Attackers can leverage this vulnerability to not only read arbitrary files but also execute commands on the underlying operating system, potentially leading to complete system compromise. The vulnerability affects multiple operating systems including Windows, OS/2, and Netware, making it particularly dangerous for organizations running mixed environments or those with legacy systems. This cross-platform nature increases the attack surface and complexity of remediation efforts, as administrators must address the vulnerability across different system architectures and file handling mechanisms.
Security professionals should recognize this vulnerability as a variant of CWE-22 Path Traversal and aligns with ATT&CK technique T1059 Command and Scripting Interpreter, specifically focusing on remote code execution through file system manipulation. The vulnerability's exploitation requires minimal technical expertise and can be automated through common web exploitation frameworks, making it particularly dangerous in environments where Apache servers are publicly accessible. Organizations should implement immediate mitigations including upgrading to Apache 2.0.40 or later versions, implementing proper input validation at the application level, and configuring web server security modules to prevent backslash-based path traversal attempts. Additionally, network-level protections such as web application firewalls and intrusion prevention systems should be configured to detect and block suspicious path traversal patterns containing backslash sequences, as the vulnerability specifically exploits the interaction between different path delimiter handling mechanisms across operating systems.