CVE-2012-2435 in Pligg
Summary
by MITRE
Directory traversal vulnerability in the captcha module in Pligg CMS before 1.2.2 allows remote authenticated users to include and execute arbitrary local files via a .. (dot dot) in the captcha parameter to module.php, as demonstrated by cross-site request forgery (CSRF) attacks.
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Analysis
by VulDB Data Team • 04/15/2017
The CVE-2012-2435 vulnerability represents a critical directory traversal flaw within the captcha module of Pligg CMS versions prior to 1.2.2. This vulnerability specifically affects the module.php script which processes captcha parameters, creating an exploitable condition that allows authenticated remote attackers to manipulate file inclusion mechanisms. The flaw stems from insufficient input validation and sanitization of the captcha parameter, which directly influences how the system resolves file paths during captcha image generation and validation processes.
The technical exploitation of this vulnerability occurs through the manipulation of the captcha parameter to include directory traversal sequences using the .. (dot dot) notation. When an authenticated user submits a request to module.php with a specially crafted captcha parameter containing directory traversal sequences, the application fails to properly validate or sanitize the input before using it in file system operations. This allows attackers to traverse the file system hierarchy and potentially include arbitrary local files, leading to unauthorized code execution or information disclosure. The vulnerability is particularly dangerous because it leverages legitimate authentication mechanisms to gain access to sensitive system resources that should otherwise remain protected.
The operational impact of CVE-2012-2435 extends beyond simple file inclusion, as it can be effectively combined with cross-site request forgery techniques to amplify the attack surface. Attackers can craft malicious requests that appear to originate from authenticated users, making it difficult to distinguish between legitimate and malicious activity. This vulnerability enables attackers to potentially execute arbitrary code on the target system, access sensitive configuration files, or obtain administrative credentials. The implications are severe for any organization using affected Pligg CMS versions, as it provides a direct path to system compromise through authenticated user sessions.
This vulnerability aligns with CWE-22, which specifically addresses directory traversal or path traversal flaws in software systems. The weakness represents a classic input validation failure where user-supplied data is not properly sanitized before being used in file system operations. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence through code execution, as attackers can leverage the file inclusion capability to establish backdoors or escalate their privileges within the system. The vulnerability also relates to credential access patterns where attackers can potentially extract sensitive information from system files or configuration databases.
Mitigation strategies for CVE-2012-2435 primarily involve upgrading to Pligg CMS version 1.2.2 or later, which includes proper input validation and sanitization for the captcha parameter. Organizations should implement comprehensive input validation mechanisms that reject or sanitize directory traversal sequences before processing user input. Additionally, implementing proper file access controls and restricting file inclusion paths to predefined safe directories can significantly reduce the attack surface. Network segmentation and monitoring for unusual file access patterns can help detect exploitation attempts. Security headers and proper authentication controls should be enforced to prevent unauthorized access to vulnerable endpoints, while regular security assessments should be conducted to identify similar vulnerabilities in other system components.