Microsoft Uncovers SQL Server Vulnerabilities

Topping off what can only be described as a disastrous week for the security of its products, Microsoft Corp. on Thursday night said it has discovered two vulnerabilities in the two most recent versions of its popular SQL Server database software.

Four separate patches are available for these flaws on the Microsoft Security Web site.

This is the third security bulletin that Microsoft has issued in the last week. On Dec. 14, the company warned of three flaws in various versions of Internet Explorer that enable attackers to execute random files on a users machine and read and delete other files.

And on Dec. 20, Microsoft disclosed a serious vulnerability in its Windows XP operating system that enables an attacker to gain complete control of a vulnerable machine.

The more serious of the two SQL Server vulnerabilities is a buffer overrun caused by some of the functions in SQL 7.0 and 2000 that generate text messages from database queries. Some of these services dont adequately verify that the messages theyre generating can fit into the buffers that are meant to hold them. As a result, an attacker could run code of his choice in the security context of the SQL Server service or cause the service to fail completely, according to Microsofts advisory.

SQL can be configured to run in one of several contexts, but runs by default as a domain user.

The second vulnerability is a format-string vulnerability in the C runtime functions that the SQL Server functions call when its installed on Windows NT 4.0, 2000 or XP. The flaw can be exploited in one of two ways: The attacker can either load and execute a database query that calls one of the affected functions or provide inputs to a Web site or other SQL front end that would accept and process random queries that would call an affected function with the appropriate parameters.

Either of these scenarios could cause a denial of service in the SQL server.

Perhaps with some of its recent problems with Outlook-related patches in mind, Microsoft security officials added this unusual warning to the advisory they published on this issue: “The C runtime plays a crucial role in the operating system itself. While we are confident that both patches are well-tested, if there were a regression error in the C runtime, the effects would likely be serious and widespread.”