CVE-2000-1084 in SQL Server
Summary
by MITRE
The xp_updatecolvbm function in SQL Server and Microsoft 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 CVE-2000-1084 vulnerability represents a critical buffer overflow flaw in Microsoft SQL Server and MSDE implementations that specifically affects the xp_updatecolvbm extended stored procedure. This vulnerability stems from inadequate input validation within the SQL Server API for Extended Stored Procedures, creating a dangerous condition where attacker-controlled data can corrupt memory structures. The flaw manifests when the xp_updatecolvbm function processes parameters without proper boundary checks before invoking the srv_paraminfo function, which serves as the interface for parameter handling in extended procedures. This design oversight creates a pathway for malicious actors to manipulate memory layout through carefully crafted input sequences that exceed expected buffer limits.
The technical exploitation of this vulnerability occurs through the manipulation of parameter values passed to the xp_updatecolvbm function, which then triggers an improper buffer handling mechanism within the SQL Server extended procedures API. When the srv_paraminfo function receives oversized parameter data, it fails to validate the input length against allocated buffer boundaries, leading to potential stack corruption or heap manipulation. This behavior aligns with CWE-121, which categorizes buffer overflow conditions that occur when insufficient bounds checking allows data to overwrite adjacent memory locations. The vulnerability operates at the intersection of memory management and API parameter processing, making it particularly dangerous as it can be exploited through legitimate SQL Server interfaces without requiring elevated privileges for initial access.
The operational impact of CVE-2000-1084 extends beyond simple denial of service to encompass full system compromise capabilities through arbitrary code execution. Attackers can leverage this vulnerability to execute malicious code within the SQL Server process context, potentially gaining access to sensitive database information, modifying data integrity, or establishing persistent access points. The vulnerability's exploitation can lead to complete system compromise when combined with other attack vectors, as the SQL Server service typically runs with elevated privileges. This makes the vulnerability particularly attractive to threat actors targeting database environments, where the compromise of SQL Server can provide access to critical business data and potentially serve as a foothold for broader network infiltration. The vulnerability's classification under ATT&CK technique T1071.004 for application layer protocol manipulation further demonstrates its potential for lateral movement within database environments.
Mitigation strategies for CVE-2000-1084 require immediate implementation of multiple defensive measures including the application of Microsoft security patches, disabling unnecessary extended stored procedures, and implementing network segmentation controls. Organizations should prioritize the installation of Microsoft's security updates that address the buffer overflow in the xp_updatecolvbm function and related extended procedures. Network-level protections such as firewall rules that restrict access to SQL Server ports and implementation of principle of least privilege for database accounts can significantly reduce exploitation risk. Database administrators should also conduct comprehensive audits of extended stored procedures, disabling or removing any that are not essential for business operations. The vulnerability's age and widespread impact make it a critical target for immediate remediation, as the exploitation techniques remain viable against unpatched systems and represent a common entry point for database-focused attacks. Additionally, implementing proper input validation at application layers and monitoring for unusual parameter patterns can provide additional defense-in-depth measures against similar buffer overflow vulnerabilities.