CVE-2011-3771 in phpBook
Summary
by MITRE
phpBook 2.1.0 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 doc/update_smilies_1.50-1.60.php and certain other files.
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Analysis
by VulDB Data Team • 02/10/2019
The vulnerability identified as CVE-2011-3771 affects phpBook version 2.1.0, a content management system that falls under the category of web applications susceptible to information disclosure attacks. This flaw represents a significant security weakness that exposes installation paths through error messages generated during direct file access attempts. The vulnerability specifically manifests when attackers make direct requests to php files within the application's directory structure, triggering error responses that inadvertently reveal critical system information. The disclosed installation path information serves as a valuable reconnaissance tool for malicious actors seeking to understand the target environment and plan subsequent attacks.
The technical mechanism behind this vulnerability stems from inadequate error handling within the phpBook application's file processing logic. When a direct request is made to a php file such as doc/update_smilies_1.50-1.60.php or similar update scripts, the application fails to properly sanitize or suppress error messages that contain filesystem path information. This behavior aligns with CWE-209, which addresses "Information Exposure Through an Error Message," and represents a classic example of how improper error handling can lead to sensitive data exposure. The vulnerability operates at the application layer and requires no special privileges or authentication to exploit, making it particularly dangerous as it can be leveraged by any remote attacker.
The operational impact of this vulnerability extends beyond simple information disclosure, as the revealed installation paths provide attackers with crucial environmental information that can be used for further exploitation attempts. Knowledge of the actual filesystem structure enables attackers to craft more targeted attacks, potentially leading to directory traversal, local file inclusion, or other privilege escalation vulnerabilities. The exposure of installation paths also violates fundamental security principles of least privilege and defense in depth, as it provides attackers with information that should remain confidential within the application's operational environment. This vulnerability particularly affects web applications that do not implement proper input validation or error handling mechanisms, making it a common issue in legacy systems.
Mitigation strategies for CVE-2011-3771 should focus on implementing comprehensive error handling procedures and restricting direct access to sensitive application files. Organizations should ensure that all php applications implement proper error suppression mechanisms that prevent filesystem paths from appearing in user-facing error messages. The recommended approach involves configuring the web server to handle errors gracefully without exposing internal system information, as outlined in the OWASP Top Ten security guidelines. Additionally, implementing proper file access controls and restricting access to update scripts and administrative files through authentication mechanisms would significantly reduce the attack surface. The remediation process should also include updating to patched versions of phpBook where available, as this vulnerability represents a known issue that has been addressed in subsequent releases. Security teams should also consider implementing web application firewalls and intrusion detection systems that can monitor for and block suspicious direct file access patterns. The vulnerability's classification under ATT&CK technique T1083 (File and Directory Discovery) highlights the importance of implementing proper access controls and monitoring mechanisms to prevent reconnaissance activities that could lead to more serious exploitation attempts.