[ISN] Microsoft offers plug for 'critical' SQL Server holes

From: InfoSec News (isnat_private)
Date: Fri Jul 26 2002 - 01:58:44 PDT

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    By Joris Evers
    IDG News Service, 07/25/02 
    Microsoft warned of five vulnerabilities in its SQL Server 2000
    database product, the most serious of which could allow an attacker to
    take over the server.
    Deemed "critical" are three vulnerabilities in a feature that allows
    users to host multiple copies of SQL Server on a single machine. Less
    serious are two flaws in utilities for database consistency checks and
    database replication, Microsoft said in two security bulletins
    released late Wednesday.
    Two buffer overrun flaws exist in the SQL Server Resolution Service,
    which is used to direct users to the right TCP port when multiple SQL
    Server copies are installed on one system. An attacker could get full
    control over the system the database software is running on by
    exploiting these flaws, Microsoft said.
    A third flaw in the SQL Server Resolution Service is a denial of
    service vulnerability. An attacker could initiate a never-ending cycle
    of data packet exchanges between two or more database servers by
    sending a specially crafted data packet to a mechanism designed to
    check if a database server is online. The packet exchanges would
    consume most if not all of the server resources, slowing performance,
    Microsoft said.
    Previous versions of SQL Server are not vulnerable as they do not
    support multiple copies on one system and thus do not include the SQL
    Server Resolution Service, Microsoft said.
    Anybody with access to the SQL Server, for example via the Internet,
    could exploit the flaws in the Resolution Service, Microsoft said.  
    That makes those flaws more serious than the flaws in the database
    consistency check and replication tools, which can only be exploited
    by registered database users and administrators.
    A buffer overrun vulnerability exists in several Database Consistency
    Checkers that are part of database maintenance tools. A user assigned
    the already privileged db_owner or db_ddladmin role on one database
    could exploit the flaw to gain control over the complete server,
    Microsoft said.
    The database replication function has a so-called SQL Injection
    Vulnerability that could allow an attacker to gain control over the
    server. It is exploitable by anybody with user privileges on the SQL
    server, but requires a special purpose user account to be enabled.  
    This SQL Server Agent Proxy Account is disabled by default and can
    only be enabled by a server administrator, Microsoft said.
    Patches to fix the vulnerabilities are available from Microsoft's
    TechNet Web site. Users should immediately patch the SQL Server
    Resolution Service holes, while the other patch should be considered,
    Microsoft said.
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