AusCERT - ESB-2005.0035 -- NGSSoftware Insight Security Research Advisories -- Two vulnerabilities in IBM DB2

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ESB-2005.0035 -- NGSSoftware Insight Security Research Advisories -- Two vulnerabilities in IBM DB2
Date: 13 January 2005
References: ESB-2005.0036

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             AUSCERT External Security Bulletin Redistribution

     ESB-2005.0035 -- NGSSoftware Insight Security Research Advisories
                      Two vulnerabilities in IBM DB2
                              13 January 2005

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           IBM DB2 8.1 Fixpak 6 and earlier
                   IBM DB2 7.x Fixpak 11 and earlier
Publisher:         NGSSoftware
Operating System:  UNIX variants
                   Linux variants
                   Windows
Impact:            Execute Arbitrary Code/Commands
Access:            Remote/Unauthenticated

Original Bulletin: http://www.nextgenss.com/advisory.htm

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Researchers at NGSSoftware have discovered multiple critical/high risk 
vulnerabilities in IBM's DB2 Universal Database. Versions affected include

DB2 8.1 Fixpak 6 and earlier
DB2 7.x Fixpak 11 and earlier

Two of the issues, remotely exploitable buffer overflows, have been fixed in 
Fixpak 7 for DB2 8.1 and Fixpak 12 for DB2 7.x. These Fixpaks were released 
last week and they can be downloaded from

http://www-306.ibm.com/software/data/db2/udb/support/downloadv8.html - DB2 
v8.1
http://www-306.ibm.com/software/data/db2/udb/support/downloadv7.html - DB2 
v7.x

The flaws fixed in these Fixpaks equate to NGSS BUGID 98 and 101 from the 
Vendor Notification Alerts - http://www.nextgenss.com/vna.htm

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Name: IBM DB2 generate_distfile buffer overflow
Systems Affected: DB2 8.1/7.x	
Severity: High risk
Vendor URL: http://www.ibm.com/
Author: David Litchfield [ david at ngssoftware.com ]
Relates to: http://www.nextgenss.com/advisories/db2-01.txt
Date of Public Advisory: 23rd December 2004
Advisory number: #NISR2122004L
Advisory URL: http://www.ngssoftware.com/advisories/db223122004L.txt

Description
***********
IBM's DB2 database server contains a procedure, generate_distfile. This
procedure suffers from a stack based buffer overflow vulnerability.

Details
*******
The generate_distfile procedure is vulnerable to a buffer overflow
vulnerability. generate_distfile is implemented as a C function, exported by
db2dbappext.dll. It takes as its third parameter the name of a file. This
parameter can be up to 255 characters long.

One of the sub functions of generate_distfile takes the third parameter, the
user supplied filename, and appends it to the directory where DB2 has been
installed. It does this by creating a 264 byte buffer on the stack. The
subfunction then calls sqloInstancePath() to get the install path for DB2.
This returns C:\PROGRA~1\IBM\SQLLIB\DB2. \tmp\ is then appended to this.
After \tmp\ is appended the user supplied filename is appended using a while
loop that continues to copy data until a NULL terminator is found. Because
the  DB2 install path (C:\PROGRA~1\IBM\SQLLIB\DB2\tmp\) takes up some of the
buffer, if the user has supplied a thrid parameter of 255 bytes the stack
based  buffer is overflowed.

However, once the buffer is overflowed, as well as overwriting the saved
return address, a pointer is also overwritten. This pointer points to a
buffer where  the resulting full path should be copied to. This interupts a
straight return address overwrite exploit; however it can still easily be
exploited in several  ways. Due to the fact that the attacker "owns" the
pointer to where the path is copied to, they can write arbitrary data to an
arbitrary location allowing a  full compromise. Once such method would be to
overwrite the pointer to the Windows UnhandledExceptionFilter function; as
access violations aren't handled,  the UEF kicks in an as the attacker
controls the UEF the flow of execution can be redirected by the attacker to
arbitrary code.

Note - whilst the discussion has used Windows paths *nix versions of DB2 are
also vulnerable.


Fix Information
***************
IBM has written a patch and can be obtained with the latest fixpak.

http://www-306.ibm.com/software/data/db2/udb/support/downloadv8.html - DB2
v8.1
http://www-306.ibm.com/software/data/db2/udb/support/downloadv7.html - DB2
v7.x

NGSSQuirreL for DB2 (http://www.nextgenss.com/db2.htm) can be used to assess
whether your DB2 server is vulnerable to this.

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Name: IBM DB2 rec2xml buffer overflow
Systems Affected: DB2 8.1/7.x	
Severity: High risk
Vendor URL: http://www.ibm.com/
Author: David Litchfield [ mark at ngssoftware.com ]
Relates to: http://www.nextgenss.com/advisories/db2-01.txt
Date of Public Advisory: 23rd December 2004
Advisory number: #NISR2122004J
Advisory URL: http://www.ngssoftware.com/advisories/db223122004K.txt

Description
***********
IBM's DB2 database server contains a function, rec2xml, used to format a
string in XML. This function suffers from a stack based buffer overflow
vulnerability.

Details
*******
By passing an overly long 3rd parameter to the rec2xml function a stack
based buffer can be overflowed, overwriting the saved return address on the
stack. This allows an attacker to control the flow of execution and the
opportunity to execute arbitrary code.

Fix Information
***************
IBM has written a patch and can be obtained with the latest fixpak.

http://www-306.ibm.com/software/data/db2/udb/support/downloadv8.html - DB2
v8.1
http://www-306.ibm.com/software/data/db2/udb/support/downloadv7.html - DB2
v7.x

NGSSQuirreL for DB2 (http://www.nextgenss.com/db2.htm) can be used to assess
whether your DB2 server is vulnerable to this.

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