CVE-2008-6938 in Pi3Web
Summary
by MITRE
Pi3Web 2.0.3 before PL2, when installed on Windows as a desktop application and without using the Pi3Web/Conf/Intenet.pi3, allows remote attackers to cause a denial of service (crash or hang) and obtain the full pathname of the server via a request to a file in the ISAPI directory that is not an executable DLL, which triggers the crash when the DLL load fails, as demonstrated using Isapi\users.txt.
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Analysis
by VulDB Data Team • 11/11/2024
CVE-2008-6938 represents a denial of service vulnerability in Pi3Web 2.0.3 before patch level 2 when running as a desktop application on Windows systems. This vulnerability stems from improper handling of requests to non-executable files within the ISAPI directory structure. The flaw manifests when the web server attempts to load a DLL file that does not exist or cannot be executed, leading to a crash or system hang that effectively denies service to legitimate users. The vulnerability is particularly concerning because it allows remote attackers to obtain the full server pathname information, which can aid in further exploitation attempts. This type of information disclosure combined with denial of service creates a dangerous attack vector that can compromise system availability and potentially expose sensitive path information to attackers. The vulnerability specifically occurs when Pi3Web is installed without the Pi3Web/Conf/Intenet.pi3 configuration file, which would normally provide proper security controls and path validation. The attack is demonstrated using a request to Isapi\users.txt, which triggers the failure path when the system attempts to process this non-executable file as if it were a DLL. This behavior aligns with CWE-248, which addresses "Uncaught Exception" conditions where programs fail to handle exceptions properly, leading to system instability. From an operational perspective, this vulnerability can be exploited by attackers to disrupt services without requiring authentication or elevated privileges, making it particularly dangerous in production environments. The lack of proper input validation and error handling in the ISAPI module processing creates an attack surface that can be leveraged for both availability and information disclosure attacks. Security practitioners should note that this vulnerability demonstrates the importance of proper file type validation and exception handling in web server applications, particularly those that process requests through ISAPI extensions. The flaw also relates to ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through the exploitation of application-level vulnerabilities. Organizations should implement immediate mitigations including applying the vendor patch, restricting access to the ISAPI directory, and implementing proper input validation controls. The vulnerability highlights the critical need for robust error handling in web applications and the importance of not exposing internal system paths through error responses. Additionally, the absence of the required configuration file suggests that default installations may be vulnerable, emphasizing the need for proper security hardening and configuration management practices. This vulnerability serves as a reminder of how seemingly minor implementation flaws in web server components can lead to significant security consequences and operational disruptions.
The technical exploitation of this vulnerability requires minimal privileges and can be automated, making it particularly attractive to threat actors seeking to disrupt services. The specific path traversal and file loading behavior demonstrates how improper handling of file extensions and execution contexts can create exploitable conditions. Security controls should focus on implementing proper access controls for ISAPI directories, ensuring that only valid executable content can be processed through the ISAPI pipeline. The vulnerability also underscores the importance of not exposing internal system paths through error messages or response content, as this information can be leveraged for more sophisticated attacks. Organizations should consider implementing monitoring for unusual access patterns to ISAPI directories and ensure that all web server components are properly patched and configured according to security best practices. The combination of denial of service and information disclosure in a single vulnerability makes CVE-2008-6938 particularly dangerous and warrants immediate attention from security teams responsible for maintaining web server infrastructure.