CVE-2005-4358 in phpBB
Summary
by MITRE
admin/admin_disallow.php in phpBB 2.0.18 allows remote attackers to obtain the installation path via a direct request with a non-empty setmodules parameter, which causes an invalid append_sid function call that leaks the path in an error message.
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Analysis
by VulDB Data Team • 07/15/2018
The vulnerability described in CVE-2005-4358 affects phpBB version 2.0.18 and represents a sensitive information disclosure flaw that can be exploited by remote attackers to obtain the server installation path. This issue resides within the admin/admin_disallow.php file and demonstrates a classic example of improper error handling that reveals system information to unauthorized parties. The vulnerability is particularly concerning as it allows attackers to gain knowledge about the server's file system structure, which can serve as a foundation for more sophisticated attacks targeting the application or underlying infrastructure. The flaw specifically manifests when a malicious actor sends a direct request to the affected script with a non-empty setmodules parameter, creating a condition that leads to an invalid append_sid function call.
The technical implementation of this vulnerability stems from a lack of proper input validation and error handling within the phpBB administrative interface. When the setmodules parameter is provided with non-empty content, the system fails to properly process this input before attempting to call the append_sid function. This function call results in an error message that inadvertently includes the full server path where phpBB is installed. The append_sid function in phpBB is designed to handle session management and URL building, but when invoked incorrectly due to the malformed setmodules parameter, it generates an error that exposes sensitive path information. This type of information disclosure vulnerability is categorized under CWE-209, which specifically addresses error messages containing sensitive information, and aligns with ATT&CK technique T1212, which involves exploitation of information disclosure vulnerabilities to gather system information.
The operational impact of this vulnerability extends beyond simple path disclosure, as it provides attackers with crucial reconnaissance data that can be leveraged in subsequent attack phases. The leaked installation path can be used to understand the server's directory structure, potentially revealing the existence of other sensitive files or directories that might not be directly accessible through normal web browsing. This information can aid attackers in crafting more targeted attacks, including directory traversal attempts or exploitation of other vulnerabilities that might exist within the same installation. The vulnerability is particularly dangerous in environments where multiple applications share the same server, as the disclosed path information might reveal the location of other applications or their configuration files that could contain additional sensitive data or vulnerabilities. Security professionals should note that this issue represents a low-effort attack vector that can be automated, making it particularly attractive to threat actors seeking to gather intelligence on web applications.
Mitigation strategies for CVE-2005-4358 should focus on implementing proper input validation and error handling within the affected phpBB installation. Organizations should immediately upgrade to phpBB version 2.0.19 or later, as this vulnerability was patched in subsequent releases. The fix implemented in newer versions involves proper validation of the setmodules parameter and enhanced error handling that prevents the exposure of sensitive path information in error messages. Additionally, system administrators should implement proper logging and monitoring to detect unusual requests to administrative scripts that might indicate exploitation attempts. Network-level protections such as web application firewalls can help detect and block requests containing malicious setmodules parameters. The vulnerability also highlights the importance of following security best practices such as disabling unnecessary administrative scripts, implementing proper access controls, and ensuring that error messages do not contain sensitive system information. Organizations should conduct regular security assessments to identify similar vulnerabilities in their web applications and ensure that error handling mechanisms are properly configured to prevent information disclosure. This vulnerability serves as a reminder of the critical importance of proper error handling in web applications and the potential consequences of exposing system information to unauthorized users.