CVE-2005-0871 in phpBB
Summary
by MITRE
calendar_scheduler.php in Topic Calendar 1.0.1 module for phpBB, when running on a Microsoft IIS server, allows remote attackers to obtain sensitive information via invalid parameters, which reveal the path in an error message.
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Analysis
by VulDB Data Team • 07/07/2018
The vulnerability identified as CVE-2005-0871 affects the Topic Calendar 1.0.1 module for phpBB when deployed on Microsoft IIS web servers. This issue represents a classic information disclosure vulnerability that occurs when the application fails to properly validate user input parameters. The flaw manifests in the calendar_scheduler.php script which processes calendar-related scheduling functions within the phpBB forum platform. When malformed or invalid parameters are submitted to this script, the application generates error messages that inadvertently expose the server's file system paths to remote attackers.
The technical implementation of this vulnerability stems from inadequate input sanitization and error handling practices within the phpBB module. Microsoft IIS servers, unlike some other web server platforms, may handle error messages differently, often including more verbose debugging information in error responses. When the calendar_scheduler.php script encounters invalid parameters, it fails to properly sanitize the input before processing, resulting in error messages that contain absolute file paths from the server's file system. This path disclosure occurs because the application does not implement proper exception handling or input validation mechanisms that would prevent sensitive system information from being exposed through error responses.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with critical system information that can be leveraged for further exploitation. The exposed file paths can reveal the complete installation directory structure of the phpBB application, including the root directory where the forum is installed. This information significantly reduces the attack surface for potential attackers who might then attempt to exploit other vulnerabilities within the same application or target the specific server configuration. The vulnerability is particularly concerning in environments where multiple applications share the same server, as the disclosed paths might reveal the locations of other sensitive applications or data directories.
This vulnerability aligns with CWE-200, which describes information exposure through error messages, and represents a common weakness in web application security practices. The ATT&CK framework categorizes this as a reconnaissance technique where adversaries gather information about the target system to plan subsequent attacks. The vulnerability demonstrates the critical importance of proper input validation and error handling in web applications, as it shows how seemingly minor implementation flaws can provide attackers with significant system intelligence. Organizations should implement proper error handling that does not expose system paths or internal application structures in user-facing error messages.
Mitigation strategies for this vulnerability include implementing comprehensive input validation for all parameters received by the calendar_scheduler.php script, configuring the web server to suppress detailed error messages, and applying the latest security patches from phpBB developers. Administrators should also consider implementing proper logging mechanisms to detect and respond to attempts to exploit this vulnerability. The most effective long-term solution involves upgrading to a patched version of the Topic Calendar module or removing the vulnerable component entirely from the phpBB installation. Additionally, organizations should conduct regular security assessments to identify similar input validation and error handling issues across their web applications.