CVE-2000-0709 in FrontPage Server Extensions
Summary
by MITRE
The shtml.exe component of Microsoft FrontPage 2000 Server Extensions 1.1 allows remote attackers to cause a denial of service in some components by requesting a URL whose name includes a standard DOS device name.
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Analysis
by VulDB Data Team • 05/09/2019
The vulnerability identified as CVE-2000-0709 represents a classic denial of service flaw within the Microsoft FrontPage 2000 Server Extensions 1.1 implementation. This security issue specifically targets the shtml.exe component which serves as the server-side include processor for FrontPage extensions. The vulnerability arises from insufficient input validation when processing Uniform Resource Locator requests that contain DOS device names within their path components. When a remote attacker crafts a malicious URL incorporating standard DOS device names such as CON, PRN, AUX, NUL, or COM1 through COM9, the shtml.exe processor fails to properly handle these malformed requests, leading to system instability and service disruption.
The technical root cause of this vulnerability stems from the component's lack of proper sanitization of input parameters during URL parsing operations. Microsoft FrontPage 2000 Server Extensions were designed to support dynamic web content through server-side includes, but the shtml.exe module did not adequately filter or validate file path components that might contain reserved DOS device names. This flaw directly maps to CWE-20, which describes improper input validation, and specifically relates to CWE-116, concerning improper encoding or escaping of output. When the processor encounters a request containing these device names, the system's file handling mechanisms become confused, resulting in resource exhaustion or process termination that manifests as a denial of service condition.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of web applications hosted on affected servers. Attackers can exploit this weakness by simply accessing specific URLs that contain the problematic device names, requiring no authentication or special privileges. The denial of service effect can render entire web applications inaccessible to legitimate users, potentially causing significant business disruption. This vulnerability particularly affects organizations relying on FrontPage extensions for web content management, as it can be triggered through normal web browsing activities without requiring sophisticated attack techniques. The attack surface is broad since any web server running FrontPage 2000 Server Extensions 1.1 and processing requests through shtml.exe is potentially vulnerable.
Security professionals should implement immediate mitigations to address this vulnerability including applying the relevant Microsoft security patches that were released following this disclosure. Organizations should also consider implementing URL filtering mechanisms at network boundaries to block requests containing known DOS device names, though this approach may have unintended consequences for legitimate web applications. The vulnerability demonstrates the importance of proper input validation and the potential risks associated with legacy web server components. From an ATT&CK framework perspective, this vulnerability aligns with the T1499.004 technique for network denial of service, as it specifically targets availability through service disruption. Additionally, the weakness represents a classic example of how legacy software components can contain fundamental design flaws that persist across multiple versions and create ongoing security risks for organizations that fail to properly maintain their web server infrastructure.