Vulnerability Note VU#796313

Microsoft SQL Server service account registry key has weak permissions that permit privilege escalation

Overview

The Microsoft SQL Server contains a vulnerability that allows remote attackers to execute arbitrary commands with system privileges.

I. Description

The Microsoft SQL Server typically runs under a dedicated "service account" that is defined by system administrators at installation time. This definition is stored in the Windows registry with permissions that allow the SQL Server to change the value of the registry key. As a result, attackers with access to the "xp_regwrite" extended stored procedure can alter this registry key and cause the SQL Server to use the LocalSystem account as its service account. Upon rebooting the server host or restarting the SQL service, the SQL Server will run with the full administrative privileges of the LocalSystem account. This ability allows a remote attacker to submit SQL queries that can execute any command on the system with the privileges of the operating system.

II. Impact

As a precondition, this vulnerability requires the ability to modify the SQL service account registry key (for example, via the "xp_regwrite" extended stored procedure). Attackers must convince an administrator to grant this access, or they must obtain it by exploiting a second vulnerability.

This vulnerability allows attackers to weaken the security policy of the SQL Server by elevating its privileges and causing it to run in the LocalSystem security context. As a side effect, it increases the severity of vulnerabilities that allow attackers to gain the privileges of the SQL service account. In some cases, this may enable attackers to compromise the server host as well.

III. Solution

Apply a patch

Microsoft has published Security Bulletin MS02-034 to address this vulnerability. For more information, please see

http://www.microsoft.com/technet/security/bulletin/MS02-034.asp

This vulnerability also affects any products that include the Microsoft Desktop Engine (MSDE) 2000. For more information, please see

http://www.microsoft.com/technet/security/MSDEapps.asp

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	25-Jul-2002

References

http://www.microsoft.com/technet/security/bulletin/MS02-034.asp
http://www.microsoft.com/technet/security/MSDEapps.asp
http://support.microsoft.com/support/misc/kblookup.asp?id=Q316333
http://www.microsoft.com/technet/prodtechnol/sql/maintain/security/sql2ksec.asp
http://www.securityfocus.com/bid/5205

Credit

This vulnerability was discovered by Bronek Kozicki and reported to the Bugtraq mailing list on April 18, 2002.

This document was written by Jeffrey P. Lanza and is based upon information provided by Microsoft.

Other Information

Date Public	04/18/2002
Date First Published	07/25/2002 02:33:25 PM
Date Last Updated	02/05/2003
CERT Advisory	CA-2002-22
CVE Name	CAN-2002-0642
US-CERT Technical Alerts
Metric	26.58
Document Revision	22

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