Title: SQL Query Method Enables Cached Administrator Connection
to be Reused
Date: 12 June 2001
Software: Microsoft SQL Server 2000 and SQL Server 7.0
Impact: Privilege elevation
Bulletin: MS01-032

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-032.asp.

Issue:

When a client connection to a SQL Server is terminated, it remains
cached for a short period of time for performance reasons. One SQL
query method contains a flaw that has the effect of making it
possible for one user's query to reuse a cached connection that
belonged to the sa account.

Exploiting this vulnerability would enable an attacker to execute the
query using the administrator's security context. This would give
her the ability to take any desired action on the database;
moreover, it would give her the ability to run extended stored
procedures, thereby giving her the opportunity to run code of her
choice and assume
de facto control of the server itself.

Mitigating Factors:

• The vulnerability only affects servers configured to use Mixed
  Mode.
  Microsoft strongly recommends against using Mixed Mode, and
  recommends using Windows Authentication mode instead. Customers
  who
  have configured their servers to use Windows Authentication mode
  are not affected by this vulnerability.
• Terminated connections are only cached for a short period. The
  attacker would need to time her attack in order to occur during
  the
  period when an administrator's connection was in the cache.
• The query method at issue here can only be executed by an
  authenticated user. Not only would this limit the number of users
  who could exploit the vulnerability, it also would allow the
  action
  to be audited.

Patch Availability:

• A patch is available to fix this vulnerability. Please read the
  Security Bulletin
  http://www.microsoft.com/technet/security/bulletin/ms01-032.asp
  for information on obtaining this patch.

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