CVE-2001-0544 in IIS
Summary
by MITRE
IIS 5.0 allows local users to cause a denial of service (hang) via by installing content that produces a certain invalid MIME Content-Type header, which corrupts the File Type table.
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Analysis
by VulDB Data Team • 05/29/2019
This vulnerability exists in Microsoft Internet Information Services version 5.0 and represents a classic denial of service flaw that exploits improper handling of malformed MIME content headers. The vulnerability specifically targets the File Type table within IIS 5.0's configuration system, which maintains mappings between file extensions and their corresponding MIME types for proper content delivery. When a local user installs content containing an invalid MIME Content-Type header, the system's parsing mechanism becomes corrupted, leading to a complete system hang that prevents further service availability. This issue falls under the CWE-122 category of buffer overflow conditions and represents a failure in input validation and error handling within the web server's content processing pipeline.
The technical exploitation of this vulnerability occurs through the installation of malicious content that deliberately includes malformed MIME headers in the Content-Type field of HTTP responses. When IIS 5.0 processes these headers, it fails to properly validate the content type specification, causing the internal File Type table structure to become corrupted. This corruption prevents the web server from properly handling subsequent requests, resulting in a complete system hang where the service becomes unresponsive to all incoming connections. The vulnerability is particularly dangerous because it can be triggered by local users who have access to the system, making it a privilege escalation concern that could be leveraged for more severe attacks.
The operational impact of this vulnerability extends beyond simple denial of service, as it can effectively render the entire web server unavailable to legitimate users and administrators. System administrators may experience complete loss of service with no clear indication of the root cause, as the hang occurs at the core configuration level rather than in application-specific components. This type of vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and demonstrates how improper input validation can lead to system-wide failures. The vulnerability affects the availability aspect of the CIA triad, potentially disrupting business operations and making the system inaccessible to authorized users who rely on the web server for content delivery.
Mitigation strategies for this vulnerability should include implementing strict input validation for all MIME content headers and ensuring proper error handling within the IIS configuration processing. System administrators should apply the relevant Microsoft security patches that address this specific File Type table corruption issue. Additionally, implementing network segmentation and access controls can limit local user privileges to prevent unauthorized installation of malicious content. Regular security assessments should focus on validating MIME header handling within web server configurations, and monitoring systems should be configured to detect unusual patterns in HTTP response headers that might indicate attempted exploitation. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing proper input sanitization practices to prevent similar issues in web server implementations.