CVE-2011-3824 in YOURLS
Summary
by MITRE
Your Own URL Shortener (YOURLS) 1.5 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by includes/auth.php and certain other files.
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Analysis
by VulDB Data Team • 02/11/2019
The vulnerability identified as CVE-2011-3824 affects Your Own URL Shortener version 1.5, a popular open-source URL shortening application that enables users to create custom short URLs. This flaw represents a classic information disclosure vulnerability that occurs when the application fails to properly handle error conditions and instead exposes sensitive system information to remote attackers through direct file access attempts.
The technical implementation of this vulnerability stems from insufficient error handling within the YOURLS application architecture. When attackers make direct requests to specific .php files such as includes/auth.php and other related components, the system does not properly validate the request context or sanitize error responses. Instead, the application generates error messages that inadvertently reveal the full server installation path where YOURLS is deployed. This occurs because the application's error reporting mechanism lacks proper input validation and context awareness, allowing attackers to exploit the direct file access pattern to extract path information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with critical system reconnaissance data that can be leveraged for more sophisticated attacks. The exposed installation paths can reveal directory structures, file locations, and potentially even underlying server configurations that may aid in identifying other vulnerabilities or planning targeted attacks. This information disclosure can facilitate further exploitation attempts including directory traversal attacks, path-based privilege escalation, or combination attacks that exploit the revealed system structure to gain deeper access to the affected system.
Security professionals should note that this vulnerability aligns with CWE-200, which describes the improper handling of information exposure, and demonstrates characteristics consistent with ATT&CK technique T1212, which involves exploitation of information exposure vulnerabilities. The vulnerability represents a fundamental flaw in the application's security design where proper error handling and input validation mechanisms are missing, allowing attackers to exploit the application's natural error reporting behavior to gather system information.
Mitigation strategies should include implementing proper error handling throughout the application codebase, ensuring that all error messages are generic and do not contain system-specific information. Organizations should also establish proper access controls that prevent direct access to internal application files and implement proper input validation to ensure that requests are properly authenticated and authorized. Additionally, regular security audits and code reviews should be conducted to identify and remediate similar information disclosure vulnerabilities in the application's architecture and error handling procedures.
The vulnerability serves as a reminder of the importance of secure error handling practices in web applications and demonstrates how seemingly minor implementation flaws can create significant security risks. Proper implementation of the principle of least privilege and defense in depth strategies can help prevent such information disclosure scenarios from occurring in production environments. Regular updates and patch management processes should be maintained to ensure that known vulnerabilities are addressed promptly, as this particular flaw was likely resolved in subsequent versions of the YOURLS application through improved error handling mechanisms and enhanced security practices.