CVE-2006-0707 in PyBlosxom
Summary
by MITRE
PyBlosxom before 1.3.2, when running on certain webservers, allows remote attackers to read arbitrary files via an HTTP request with multiple leading / (slash) characters, which is accessed using the PATH_INFO variable.
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Analysis
by VulDB Data Team • 07/19/2018
This vulnerability exists in PyBlosxom blogging software versions prior to 1.3.2 and represents a directory traversal flaw that can be exploited through improper handling of the PATH_INFO variable in specific web server configurations. The vulnerability occurs when web servers process HTTP requests containing multiple leading forward slashes in the URL path, allowing attackers to manipulate the application's internal file resolution mechanism. The flaw specifically affects systems where PyBlosxom operates in an environment where the PATH_INFO variable is used to determine the requested resource path, creating a scenario where the application fails to properly sanitize or validate the input before processing file operations.
The technical implementation of this vulnerability stems from the application's failure to normalize or validate the PATH_INFO variable, which typically contains the path component of the URL after the script name. When multiple leading slashes are present in the request, the application interprets these as part of the intended path without proper sanitization, potentially allowing access to files outside the intended document root or blog directory structure. This type of vulnerability falls under the CWE-22 category for Improper Limitation of a Pathname to a Restricted Directory, commonly known as directory traversal or path traversal attacks. The vulnerability is particularly dangerous because it can be exploited without requiring authentication and can potentially allow access to sensitive system files, configuration data, or other resources that should remain protected.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can provide attackers with unauthorized access to the underlying file system and potentially enable further exploitation. An attacker can construct malicious requests with multiple leading slashes to traverse directories and access files such as configuration files, database files, or even system-level files that contain sensitive information. The vulnerability is especially concerning in shared hosting environments or when PyBlosxom is deployed with insufficient security hardening. According to ATT&CK framework, this vulnerability maps to T1083 (File and Directory Discovery) and potentially T1566 (Phishing) if the attacker can use the disclosed information to craft more sophisticated attacks. The attack surface is broad as it affects any system running PyBlosxom 1.3.1 or earlier on web servers that properly populate the PATH_INFO variable.
Mitigation strategies for this vulnerability include immediate upgrading to PyBlosxom version 1.3.2 or later, which contains proper input validation for the PATH_INFO variable. Organizations should also implement proper web server configuration to prevent multiple leading slashes from being passed to the application, and consider implementing input sanitization at the web server level. Additional protective measures include restricting file permissions on the server, implementing proper access controls, and monitoring for unusual file access patterns. The vulnerability highlights the importance of proper input validation and the principle of least privilege in web application security. Security teams should also implement regular vulnerability scanning and application security testing to identify similar path traversal issues in other applications. Organizations running legacy versions of PyBlosxom should consider implementing web application firewalls or security modules that can detect and block such malicious path traversal attempts before they reach the vulnerable application layer.