CVE-2002-0186 in SQL Server
Summary
by MITRE
Buffer overflow in the SQLXML ISAPI extension of Microsoft SQL Server 2000 allows remote attackers to execute arbitrary code via data queries with a long content-type parameter, aka "Unchecked Buffer in SQLXML ISAPI Extension."
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Analysis
by VulDB Data Team • 04/22/2025
The vulnerability identified as CVE-2002-0186 represents a critical buffer overflow flaw within the SQLXML ISAPI extension component of Microsoft SQL Server 2000. This security weakness specifically manifests when processing data queries that contain excessively long content-type parameters, creating an unchecked buffer condition that can be exploited by remote attackers to execute arbitrary code on the affected system. The vulnerability resides in the ISAPI extension's improper handling of input validation, particularly concerning the content-type header parameter that is commonly used in web-based data queries.
The technical implementation of this flaw occurs within the SQLXML ISAPI extension module where insufficient bounds checking is performed on incoming content-type parameters. When a maliciously crafted HTTP request is sent to the SQL Server 2000 instance with an overly long content-type value, the extension fails to properly validate the input length before copying it into a fixed-size buffer. This classic buffer overflow condition allows attackers to overwrite adjacent memory locations, potentially corrupting the program's execution flow and enabling arbitrary code execution with the privileges of the SQL Server service account. The vulnerability is particularly dangerous because it operates at the ISAPI extension level, which means it can be triggered through standard web-based attacks against SQL Server's XML query capabilities.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with a pathway to compromise entire database servers and potentially access sensitive data repositories. Since SQL Server 2000 was widely deployed in enterprise environments, this vulnerability created a significant attack surface that could be leveraged to gain unauthorized access to critical business data. The remote exploitation capability means that attackers do not require physical access to the server or local network privileges to exploit the vulnerability, making it particularly attractive for automated attack tools. Additionally, the vulnerability affects systems that have enabled the SQLXML ISAPI extension, which was commonly enabled in production environments to support XML-based data querying features.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant Microsoft security patches that address the buffer overflow in the SQLXML ISAPI extension. The recommended approach involves disabling the SQLXML ISAPI extension on systems where it is not absolutely required, or ensuring that all systems are updated with the latest security patches from Microsoft. Network-level protections such as firewall rules that restrict access to the SQL Server ports and implementing web application firewalls can provide additional defense-in-depth measures. From a compliance perspective, this vulnerability aligns with CWE-121 which addresses stack-based buffer overflow conditions, and it maps to ATT&CK technique T1059.007 for execution through web shells and command injection. Organizations should also consider implementing intrusion detection systems to monitor for suspicious HTTP requests containing unusually long content-type headers that could indicate exploitation attempts. The vulnerability serves as a prime example of why proper input validation and bounds checking are critical security practices, particularly in web-facing applications and extensions that process untrusted data from external sources.