CVE-2011-3773 in PHPDevShell
Summary
by MITRE
PHPDevShell 3.0.0-Beta-4b 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 gzip.php.
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Analysis
by VulDB Data Team • 02/10/2019
CVE-2011-3773 represents a sensitive information disclosure vulnerability affecting PHPDevShell version 3.0.0-Beta-4b. This vulnerability resides in the application's error handling mechanism where direct requests to php files trigger error messages containing the installation path. The flaw demonstrates a classic path disclosure issue that can be exploited by remote attackers to gain insights into the target system's file structure and deployment configuration. The vulnerability specifically manifests when attackers make direct requests to files such as gzip.php, which generates error messages revealing the absolute path where PHPDevShell is installed on the server. This type of information disclosure can significantly aid attackers in planning subsequent attacks by providing them with critical system information that would otherwise remain hidden.
The technical nature of this vulnerability aligns with CWE-200, which categorizes information exposure issues where sensitive data is inadvertently revealed to unauthorized users. The flaw represents a failure in input validation and error handling practices within the PHPDevShell application. When the application encounters an error during processing of direct file requests, it fails to sanitize error messages properly, allowing the installation path to be exposed in plain text. This particular implementation demonstrates poor security hygiene in error message generation, where developers did not implement proper error handling that would prevent sensitive path information from being exposed to remote users. 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 CVE-2011-3773 extends beyond simple information disclosure, as the revealed installation path provides attackers with a foundation for more sophisticated attacks. Knowledge of the exact file system structure enables attackers to craft targeted attacks that exploit other vulnerabilities present in the same application or related systems. The exposure of the installation path can facilitate directory traversal attacks, help in identifying other potentially vulnerable components, and provide attackers with information needed to bypass security controls. Additionally, this vulnerability can be combined with other techniques to build more comprehensive attack vectors, such as identifying the exact version of PHPDevShell installed or mapping the complete application structure. From an attacker's perspective, this information disclosure serves as a reconnaissance tool that significantly reduces the effort required to perform more advanced exploitation techniques.
The vulnerability can be mitigated through several approaches that align with established security practices and frameworks. The primary remediation involves implementing proper error handling that prevents sensitive information from being exposed in error messages. This includes configuring the application to display generic error messages to end users while logging detailed technical information internally for administrators. The application should be configured to disable direct access to php files that are not intended for public access, and proper input validation should be implemented to prevent malformed requests from triggering error conditions. Security hardening measures should include setting appropriate permissions on files and directories, implementing proper logging mechanisms, and ensuring that error messages do not contain system-specific information. Organizations should also consider implementing web application firewalls that can detect and block suspicious requests attempting to access internal files directly. These mitigations align with the principle of least privilege and defense in depth strategies recommended in various security frameworks including the NIST Cybersecurity Framework and ISO 27001 standards. The vulnerability serves as a reminder of the critical importance of proper error handling and input validation in web applications, emphasizing that seemingly minor implementation flaws can have significant security implications.