[Full-disclosure] Details for BID 19586 - DB2 UDB Vulnerability

DB2 UDB - Handshake Protocol DoS Attack (BID 19586)

Background

DB2 Universal Database (UDB)(tm) is a popular database software package
from IBM available for legacy platforms as well as open systems (Unix
and Windows). Clients use a protocol called DRDA to communicate with the
DB2 UDB server. Protocol messages are used for session setup,
authentication and data transfer.

Scope

Imperva's Application Defense Center is conducting an extensive research
of the DRDA protocol and its implementation. As part of the research the
team has identified vulnerability in DB2 UDB's connection establishment
mechanism that allows an attacker to terminate the UDB service,
effectively denying service from all database users.

Findings

An attacker can send a specially crafted ACCSEC command during the
handshake process with the server, causing the server process to crash.

Details

A simple connection establishment process to the DB2 UDB server with a
user-password authentication consists of several commands: EXCSAT
(Exchange Server Attributes), ACCSEC (Access Security), SECCHK (Security
Check) and ACCRDB (Access RDB). The RDBNAM parameter, which appears in
some of them, specifies the name of the RDB that the command accesses
(according to the documentation, if this parameter is specified, its
value must be the same as the value specified on the ACCRDB command for
RDBNAM). ACCSEC usually appears twice during the handshake process.

It turns out that if the RDBNAM parameter is omitted from the first
ACCSEC command, the DB2 UDB server becomes unstable, while the
establishment of the connection may continue successfully. Once the
connection is established, a simple command (such as SELECT) sent
through the connection causes the service to terminate unexpectedly.

Exploit

Send a connection establishment request to the DB2 UDB server, where the
RDBNAM parameter is omitted from the first ACCSEC command. After the
connection is established, send a simple query (e.g.: SELECT * FROM
dummy).

Tested Versions

Vulnerable

DB2 UDB version 8.x all platforms.

Not Vulnerable

Vendor's Status

January 11th 2006 - Vendor Notified

August 14th 2006 - Patched in UDB 8.1 FixPak 13, APAR is IY87211

August 18th 2006 - Reported by vendor to Bugtraq and labeled as BID
19586

Workaround

None.

Credit

Discovered by Tal Ryterski from Imperva Inc.

Amichai Shulman
CTO

<http://www.imperva.com/&gt; Imperva, Inc.
12 Hachilazon St.
Ramat Gan
Israel

(972) 3-6120133 x103 Office
(972) 54-5885083 Mobile
(972) 3-5711133 Fax
[email protected]

… <http://imperva.com/go/nc/&gt;

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