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CERT Coordination Center

ISC BIND 8 contains buffer overflow in transaction signature (TSIG) handling code

Vulnerability Note VU#196945

Original Release Date: 2001-01-29 | Last Revised: 2002-05-01

Overview

The Berkeley Internet Name Domain (BIND) is an implementation of the Domain Name System (DNS) by the Internet Software Consortium (ISC). There is a buffer overflow vulnerability in BIND 8.2.x, which may allow remote intruders to gain access to systems running BIND. DNS servers running BIND 8 are responsible for the majority of name resolution services on the Internet.

This vulnerability has been successfully exploited in a laboratory environment and presents a serious threat to the Internet infrastructure.

Description

During the processing of transaction signatures, BIND performs a test for signatures that fail to include a valid key. If a transaction signature is found in the request, but a valid key is not included, BIND skips normal processing of the request and jumps directly to code designed to send an error response. Because this code fails to initialize variables in the same manner as the normal processing, later function calls make invalid assumptions about the size of the request buffer. In particular, the code to add a new (valid) signature to the response may overflow the request buffer and overwrite adjacent memory on the stack or heap. Overwriting this memory can allow an intruder (in conjunction with other buffer overflow exploit techniques) to gain unauthorized access to the vulnerable system.

The flawed program logic is distributed over several function calls within the BIND software. When the attacker sends a UDP request, the packet will be loaded into a buffer on the stack (u.buf) by the function datagram_read(). On the other hand, TCP requests are loaded into a buffer (sp->s_buf) on the heap by the function stream_getmsg(). Regardless of the protocol, each of these functions call dispatch_message(), which in turn calls ns_req().

The ns_req() function handles the request. A call to ns_find_tsig() determines if a transaction signature exists in the request, and find_key() is called thereafter to determine if a valid key has been included. In the case where a transaction signature is found but the key is NULL, msglen is computed to include only the portion of the request before the signature. This is where the problem occurs, because the variables buflen and msglen are assumed through most of the code to add up to the total size of the buffer allocated for holding the request.

BIND uses the same buffer for storing the request and generating the response. Specifically, the response is composed by appending an error code and a transaction signature to the existing request. Since the new transaction signature is supposed to overwrite the signature of the request, msglen was modified to reflect the request length minus the signature length. However, buflen was not modified to reflect the new value of msglen, causing subsequent function calls (specifically ns_sign) to cause BIND to overwrite memory adjacent to the packet buffer.

These overwrites may allow an intruder to create conditions required for the execution of arbitrary code. Because the overflows occur on the stack for UDP requests and on the heap for TCP requests, the specific details of the exploit begin to differ at this point. Both scenarios result in the same impact -- the attacker can execute arbitrary code on the vulnerable system.

For more information on transaction signatures, please visit:

Impact

This vulnerability may allow an attacker to execute privileged commands or code with the same permissions as the BIND server. Because BIND is typically run by a superuser account, the execution would occur with superuser privileges.

Solution

The ISC has released BIND version 8.2.3 to address this security issue as well as others. The CERT/CC strongly recommends that all users of BIND 8.2.x upgrade to 8.2.3 immediately. The ISC recommends that users affected by this vulnerability upgrade to either BIND 8.2.3 or BIND 9.1.

The BIND 8.2.3 distribution can be downloaded from:


The BIND 9.1 distribution can be downloaded from:

Please note that upgrading to BIND 8.2.3 also addresses the information leakage vulnerability discussed in VU#325431.

Vendor Information

196945
 
Affected   Unknown   Unaffected

Caldera

Notified:  January 18, 2001 Updated:  January 29, 2001

Status

  Vulnerable

Vendor Statement

OpenLinux 2.3, eServer 2.3.1 and eDesktop 2.4 are all vulnerable.

Update packages will be provided at

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Compaq Computer Corporation

Notified:  January 18, 2001 Updated:  April 04, 2001

Status

  Vulnerable

Vendor Statement

COMPAQ COMPUTER CORPORATION

------------------------------------------------------------------------------------
VU#196945 - BIND 8 contains buffer overflow in transaction signature handling code
X-REF: SSRT1-66U, SSRT1-68U
------------------------------------------------------------------------------------
Compaq Tru64 UNIX V5.1 -
V5.1 patch: SSRT1-66U_v5.1.tar.Z

Compaq Tru64 UNIX V5.0 & V5.0a -
V5.0 patch: SSRT1-68U_v5.0.tar.Z
V5.0a patch: SSRT1-68U_v5.0a.tar.Z

Compaq Tru64 UNIX V4.0D/F/G - Not Vulnerable

TCP/IP Services for Compaq OpenVMS - Not Vulnerable

------------------------------------------------------------------------------------
Compaq will provide notice of the completion/availability of the patches
through AES services (DIA, DSNlink FLASH), the Security mailing list (**),
and be available from your normal Compaq Support channel.

**You may subscribe to the Security mailing list at:

http://www.support.compaq.com/patches/mailing-list.shtml

Software Security Response Team
COMPAQ COMPUTER CORPORATION

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Conectiva

Notified:  January 29, 2001 Updated:  April 04, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Conectiva Linux has made an announcement regarding this vulnerability; for further information, please see:

Debian

Notified:  January 18, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Debian has made an announcement regarding this vulnerability; for further information, please see:

FreeBSD

Notified:  January 18, 2001 Updated:  May 11, 2001

Status

  Vulnerable

Vendor Statement

No supported version of FreeBSD contains BIND 4.x, so this does not affect us. We currently ship betas of 8.2.3 in the FreeBSD 4.x release branch, and will be upgrading to 8.2.3 once it is released.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

FreeBSD has released the following advisory regarding this issue:

IBM

Notified:  January 18, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

[A fix for this vulnerability] can be downloaded from ftp://ftp.software.ibm.com/aix/efixes/security. The compressed tarfile is multiple_bind_vulns_efix.tar.Z. Installation instructions and other important information are given in the README file that is included in the tarball.

The official fix for the four BIND4 and BIND8 vulnerabilities will be in APAR #IY16182.

AIX Security Response Team
IBM Austin

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

ISC

Notified:  January 05, 2001 Updated:  April 04, 2001

Status

  Vulnerable

Vendor Statement

Name:"tsig bug"
Versions:8.2, 8.2-P1, 8.2.1, 8.2.2, 8.2.2-P1, 8.2.2-P2, 8.2.2-P3,
8.2.2-P4, 8.2.2-P5, 8.2.2-P6, 8.2.2-P7 and all 8.2.3 betas.
Severity:CRITICAL
Exploitable:Remotely
Type:Access possible

Description:

It is possible to overflow a buffer handling TSIG signed
queries, thereby obtaining access to the system.

Workarounds:

None.

Active Exploits:

Exploits for this bug exist.

Solution:

Upgrade to BIND 8.2.3-REL or preferably BIND 9.1.

Credits:

Discovery and initial documentation of this vulnerability
was conducted by Anthony Osborne and John McDonald of the
COVERT Labs at PGP Security.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The ISC has posted this information on their web site at:


The source code for ISC BIND can be downloaded from:

Immunix

Notified:  January 31, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Immunix has made an announcement regarding this vulnerability; for further information, please see:

MandrakeSoft

Notified:  February 03, 2001 Updated:  April 04, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

MandrakeSoft has made an announcement regarding this vulnerability; for further information, please see:

NetBSD

Notified:  January 18, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please see NetBSD-SA2001-001, "Security vulnerabilities in BIND" at:

RedHat

Notified:  January 18, 2001 Updated:  April 04, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

RedHat has released an advisory regarding this vulnerability; for further information, please see RHSA-2001-007 and associated bug reports at:

SCO

Notified:  January 18, 2001 Updated:  May 01, 2002

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Caldera UNIX has published Security Advisory CSSA-2002-SCO.16 to address this issue in their UnixWare product line. For more information, please see:

Slackware

Notified:  February 03, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Slackware has made an announcement regarding this vulnerability; for further information, please see:

SuSE

Notified:  February 03, 2001 Updated:  April 05, 2001

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

SuSE has made an announcement regarding this vulnerability; for further information, please see:

Sun

Notified:  January 18, 2001 Updated:  August 07, 2001

Status

  Vulnerable

Vendor Statement

CERT Advisory CA-2001-02 describes four vulnerabilities in certain

versions of BIND.  The four vulnerabilities are listed below along with
the affected versions of Solaris and the version of BIND shipped with each
version of Solaris.

VU#196945 - ISC BIND 8 contains buffer overflow in transaction signature (TSIG)
            handling code

    Solaris 8 04/01* (BIND 8.2.2-p5)
    Solaris 8 Maintenance Update 4* (BIND 8.2.2-p5)

VU#572183 - ISC BIND 4 contains buffer overflow in nslookupComplain()

    Solaris 2.6 (BIND 4.9.4-P1)
    Solaris 2.5.1** (BIND 4.9.3)

VU#868916 - ISC BIND 4 contains input validation error in nslookupComplain()

    Solaris 2.6 (BIND 4.9.4-P1)
    Solaris 2.5.1** (BIND 4.9.3)

VU#325431 - Queries to ISC BIND servers may disclose environment variables

    Solaris 2.4, 2.5 (BIND 4.8.3)
    Solaris 2.5.1** (BIND 4.9.3 and BIND 4.8.3)
    Solaris 2.6 (BIND 4.9.4-P1)
    Solaris 7 and 8 (BIND 8.1.2)

*  To determine if one is running Solaris 8 04/01 or Solaris 8 Maintenance
   Update 4, check the contents of the /etc/release file.

** Solaris 2.5.1 ships with BIND 4.8.3 but patch 103663-01 for SPARC and
   103664-01 for x86 upgrades BIND to 4.9.3, current revision for each
   patch is -17.

List of Patches

 The following patches are available in relation to the above problems.

 OS Version               Patch ID
 __________               _________
 SunOS 5.8                109326-04
 SunOS 5.8_x86            109327-04
 SunOS 5.7                107018-03
 SunOS 5.7_x86            107019-03
 SunOS 5.6                105755-10
 SunOS 5.6_x86            105756-10
 SunOS 5.5.1              103663-16
 SunOS 5.5.1_x86          103664-16
 SunOS 5.5                103667-12
 SunOS 5.5_x86            103668-12
 SunOS 5.4                102479-14
 SunOS 5.4_x86            102480-12

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

For the full text of Sun Microsystems Security Bulletin #204, please visit

http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doctype=coll&doc=secbull/204&type=0&nav=sec.sba

This document has been archived here

sun-security-bulletin-204.txt

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Apple

Notified:  January 18, 2001 Updated:  April 05, 2001

Status

  Not Vulnerable

Vendor Statement

Apple plans to include BIND 8.2.3 in Mac OS X. BIND is not enabled by default in Mac OS X or Mac OS X Server.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Hewlett Packard

Notified:  January 18, 2001 Updated:  May 10, 2001

Status

  Not Vulnerable

Vendor Statement

None of the Bind versions of HP-UX is vulnerable to VU#196945 - problem of buffer overflow in TSIG handling code.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

HP has released a Security Bulletin to address this issue; for further information, please visit http://itrc.hp.com and search for "HPSBUX0102-144". Please note that registration may be required to access this document.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Microsoft

Notified:  January 18, 2001 Updated:  January 30, 2001

Status

  Not Vulnerable

Vendor Statement

Microsoft's implementation of DNS is not based on BIND, and is not affected by this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

OpenBSD

Notified:  January 18, 2001 Updated:  January 30, 2001

Status

  Not Vulnerable

Vendor Statement

So we are pretty impressed with ourselves, since it looks like none of these BIND bugs affected us. In '97, a couple of us did some sprintf->snprintf whacking. Probably took about 3 minutes.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

BSDI

Notified:  January 18, 2001 Updated:  January 26, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Data General

Notified:  January 18, 2001 Updated:  January 26, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Fujitsu

Notified:  January 18, 2001 Updated:  January 26, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NEC

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NeXT

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

SGI

Notified:  January 18, 2001 Updated:  April 27, 2001

Status

  Unknown

Vendor Statement

SGI's IRIX (tm) operating system contains base BIND 4.9.7 with SGI modifications. IRIX BIND 4.9.7 is vulnerable to buffer overflow in nslookupComplain(). Patches are forth coming and will be released with an advisory to http://www.sgi.com/support/security/ when available.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

SGI has released an advisory regarding this vulnerability. For further information, please visit

Sequent

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Siemens Nixdorf

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sony

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Unisys

Notified:  January 18, 2001 Updated:  January 27, 2001

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

The CERT/CC thanks the COVERT Labs at PGP Security for discovering and analyzing this vulnerability and the Internet Software Consortium for providing a patch to fix it.

This document was written by Cory F Cohen.

Other Information

CVE IDs: CVE-2001-0010
CERT Advisory: CA-2001-02
Severity Metric: 50.87
Date Public: 2001-01-29
Date First Published: 2001-01-29
Date Last Updated: 2002-05-01 19:01 UTC
Document Revision: 59

Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.