CVE-2000-1086 in SQL Server
Summary
by MITRE
The xp_printstatements function in Microsoft SQL Server 2000 and SQL Server Desktop Engine (MSDE) does not properly restrict the length of a buffer before calling the srv_paraminfo function in the SQL Server API for Extended Stored Procedures (XP), which allows an attacker to cause a denial of service or execute arbitrary commands, aka the "Extended Stored Procedure Parameter Parsing" vulnerability.
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Analysis
by VulDB Data Team • 04/24/2017
The xp_printstatements function in Microsoft SQL Server 2000 and SQL Server Desktop Engine represents a critical buffer overflow vulnerability that stems from inadequate input validation within the extended stored procedure interface. This flaw exists within the SQL Server API for Extended Stored Procedures where the srv_paraminfo function is invoked without proper bounds checking on parameter lengths. The vulnerability manifests when the xp_printstatements function processes user-supplied input that exceeds predetermined buffer limits, creating a condition where memory corruption can occur during parameter parsing operations.
This vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, specifically affecting the parameter handling mechanism within extended stored procedures. The flaw enables attackers to manipulate the memory layout of the SQL Server process through carefully crafted input sequences that exceed the expected buffer capacity. When the srv_paraminfo function attempts to process these oversized parameters, it overwrites adjacent memory locations, potentially leading to unpredictable behavior including application crashes, denial of service conditions, or more severe exploitation scenarios.
The operational impact of this vulnerability extends beyond simple denial of service to encompass potential remote code execution capabilities. Attackers can leverage this flaw to execute arbitrary commands on the target system with the privileges of the SQL Server service account, which typically operates with elevated system permissions. The vulnerability affects both SQL Server 2000 and MSDE installations, making it particularly dangerous as it impacts both enterprise and desktop database deployments. The exploitation requires minimal privileges since the vulnerability exists within the extended procedure framework that is designed to allow system-level operations.
From a threat modeling perspective, this vulnerability maps to multiple ATT&CK techniques including T1059.001 for command and script interpreter, T1068 for exploit for privilege escalation, and T1489 for denial of service. The attack surface is broad as it affects any system running vulnerable SQL Server versions, and the exploitation can occur through various attack vectors including direct database connections or through web applications that interface with SQL Server databases. The vulnerability demonstrates the inherent risks of extended stored procedures and improper input validation in database systems.
Mitigation strategies for this vulnerability require immediate patching of affected SQL Server installations through Microsoft security updates, as no effective workarounds exist for this specific buffer overflow condition. Organizations should implement network segmentation to limit access to SQL Server instances and restrict the permissions of database accounts to minimize potential impact if exploitation occurs. Security monitoring should focus on detecting unusual database activity patterns and parameter inputs that might indicate attempted exploitation. Additionally, implementing proper input validation at application layers and maintaining up-to-date security patches for all database systems represents the most effective defense against this and similar vulnerabilities in database environments.