CVE-2006-2770 in pppBLOG
Summary
by MITRE
Directory traversal vulnerability in randompic.php in pppBLOG 0.3.8 and earlier, when register_globals is enabled, allows remote attackers to read arbitrary files via a .. (dot dot) sequence in an index of the "file" array parameter, as demonstrated by file[0].
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Analysis
by VulDB Data Team • 06/21/2019
The vulnerability described in CVE-2006-2770 represents a classic directory traversal flaw affecting pppBLOG version 0.3.8 and earlier installations. This security weakness specifically targets the randompic.php script within the blogging platform, creating a pathway for remote attackers to access arbitrary files on the server filesystem. The vulnerability is particularly concerning because it leverages the dangerous register_globals PHP configuration setting, which automatically converts HTTP request variables into PHP global variables without proper sanitization. When register_globals is enabled, the malicious input can be directly incorporated into the application's execution context, bypassing normal input validation mechanisms. The attack vector involves crafting a specially formatted request containing a .. (dot dot) sequence within the file array parameter, specifically targeting file[0] in the demonstration exploit.
The technical implementation of this vulnerability stems from inadequate input validation and improper file path handling within the randompic.php script. When the application processes the file parameter without proper sanitization, it directly incorporates user-supplied input into file system operations. This creates an opportunity for attackers to manipulate the file path resolution by inserting directory traversal sequences that navigate upward through the filesystem hierarchy. The CWE-22 classification applies directly to this vulnerability, as it represents a weakness where untrusted input is used to construct file paths without proper validation, allowing access to unintended resources. The flaw operates at the application layer and can be classified under the ATT&CK technique T1083 (File and Directory Discovery) as attackers can enumerate and access arbitrary files on the compromised system.
The operational impact of this vulnerability extends beyond simple information disclosure, as successful exploitation can lead to complete system compromise. Attackers can potentially access sensitive configuration files, database credentials, user data, and other confidential information stored on the server. The vulnerability is particularly dangerous in environments where pppBLOG is deployed with register_globals enabled, which was common in older PHP configurations but is now considered a security risk. The remote nature of the attack means that an attacker can exploit this weakness from anywhere on the internet without requiring local access or authentication. This makes the vulnerability particularly attractive to automated attack tools and increases the potential for widespread exploitation across multiple systems.
Mitigation strategies for this vulnerability focus on both immediate remediation and long-term architectural improvements. The most effective immediate fix involves disabling the register_globals PHP configuration setting, which eliminates the automatic conversion of request variables into global scope. Additionally, developers should implement proper input validation and sanitization techniques, including whitelisting acceptable file paths and using secure file access methods that prevent directory traversal sequences. The application code should validate that all user-supplied input conforms to expected patterns and reject any input containing directory traversal sequences. Organizations should also consider implementing web application firewalls that can detect and block suspicious file path patterns. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in other components of the application stack, as this type of flaw often indicates broader security issues within the software architecture. The vulnerability serves as a reminder of the importance of secure coding practices and the dangers of legacy PHP configurations that were once common but are now considered deprecated security risks.