CVE-2001-0276 in Badblue
Summary
by MITRE
ext.dll in BadBlue 1.02.07 Personal Edition web server allows remote attackers to determine the physical path of the server by directly calling ext.dll without any arguments, which produces an error message that contains the path.
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Analysis
by VulDB Data Team • 10/07/2025
The vulnerability identified as CVE-2001-0276 represents a critical information disclosure flaw within the BadBlue 1.02.07 Personal Edition web server software. This issue resides in the ext.dll component which serves as a critical subsystem for the web server's operation. The vulnerability manifests when attackers can directly access this dynamic link library without proper authentication or input validation, enabling them to extract sensitive system information through a simple method invocation. The flaw operates by leveraging the server's response mechanism to malformed or empty requests, where the system's error handling routine inadvertently reveals the physical file path structure of the underlying operating system.
This vulnerability directly maps to CWE-200, which classifies information exposure issues in software systems. The technical implementation of this flaw demonstrates a classic case of insufficient error handling within the web server's architecture. When ext.dll receives a request without arguments, it fails to properly sanitize or validate the input before processing, resulting in the generation of an error message that contains unfiltered system path information. The error message response includes the complete physical path to the server installation directory, which provides attackers with crucial reconnaissance data for subsequent exploitation attempts. This type of information disclosure vulnerability enables attackers to understand the server's file structure, which can significantly aid in planning more sophisticated attacks.
The operational impact of this vulnerability extends beyond simple path disclosure, as it creates a foundation for more advanced exploitation techniques. Attackers can use the discovered path information to map the server's directory structure, identify potential weak points in the file system, and plan targeted attacks against specific files or directories. The vulnerability affects the confidentiality aspect of the security triad by exposing sensitive system information that should remain hidden from unauthorized users. This disclosure can facilitate directory traversal attacks, file inclusion vulnerabilities, and other exploitation techniques that rely on knowledge of the server's physical file structure. The vulnerability's exploitation requires minimal technical skill and can be accomplished through simple web requests, making it particularly dangerous in environments where the web server is exposed to untrusted networks.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and error handling within the web server's architecture. System administrators should immediately apply patches or updates provided by the vendor to address this specific flaw in the ext.dll component. The recommended approach involves configuring the web server to suppress detailed error messages and implement proper access controls that prevent direct access to system components without proper authentication. Organizations should also implement network segmentation and firewall rules to limit access to the web server's internal components. Additionally, security monitoring should be enhanced to detect unusual access patterns that might indicate exploitation attempts. This vulnerability highlights the importance of following secure coding practices and adhering to the principle of least privilege when designing web server applications. The flaw demonstrates how simple error handling issues can create significant security risks, emphasizing the need for comprehensive security testing and code review processes that identify such information disclosure vulnerabilities before they can be exploited by malicious actors.