BIND T_NXT record processing may cause buffer overflow

Overview

A vulnerability in BIND, repaired in verison 8.2.2p5, allows remote attackers to execute code with the privileges of the process running named. This vulnerability was widely exploited from November 1999 to December 2000.

Description

There is a buffer overflow in the processing of NXT records in the routine rrextract, part of the file ns_resp.c. Specifically, in vulnerable versions of BIND, there is a section of code which reads:

case T_NXT:
n = dn_expand(msg, eom, cp, (char *)data, sizeof data);
if (n < 0) {
hp->rcode = FORMERR;
return (-1);
}
if (!ns_nameok((char *)data, class, NULL, response_trans,
domain_ctx, dname, from.sin_addr)) {
hp->rcode = FORMERR;
return (-1);
}
cp += n;
cp1 = data + strlen((char *)data) + 1;
memcpy(cp1, cp, dlen - n);

The value of the dlen can be influenced by an intruder in such a way that the expression ‘dlen - n’ is larger than the size allocated to cp1. Further, the contents of cp can be influenced by an intruder. Thus, this vulnerability can be exploited to execute arbitrary code with the privileges of the process running named.

An exploit for this vulnerability is publicly available .

NXT record processing was introduced to BIND in version 8.2. 8.1.2 and earlier (including 4.9.x) do not appear to be vulnerable to this problem.

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Impact

Remote user may gain default process access of local nameserver, usually root

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Solution

Upgrade to the latest version of BIND.

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Vendor Information

16532

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The SCO Group (SCO Unix) __ Affected

Updated: January 28, 2001

Status

Affected

Vendor Statement

Santa Cruz Operation, Inc

Security patches for the following SCO products will
be made available at <http://www.sco.com/security&gt;

UnixWare 7.x.x is also reported to be vulnerable
UnixWare 2.x.x is also reported to be vulnerable

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](<mailto:[email protected]?Subject=VU%2316532 Feedback>).

Fujitsu __ Not Affected

Updated: January 28, 2001

Status

Not Affected

Vendor Statement

Regarding the BIND related vulnerabilities VU#16532/VU#13145/VU#4512, Fujitsu’s UXP/V operating system is not vulnerable.

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](<mailto:[email protected]?Subject=VU%2316532 Feedback>).

Sun Microsystems, Inc. __ Not Affected

Updated: January 28, 2001

Status

Not Affected

Vendor Statement

After [] investigation, we have concluded that we are also not vulnerable to Vulnerability #2. Therefore please state that Sun is not vulnerable for both VU#16532 and VU#13145…

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](<mailto:[email protected]?Subject=VU%2316532 Feedback>).

Compaq Computer Corporation __ Unknown

Updated: January 28, 2001

Status

Unknown

Vendor Statement

COMPAQ COMPUTER CORPORATION
-----------------------------

At the time of writing this document, Compaq is currently investigating
the potential impact to Compaq’s BIND release(s).

As further information becomes available Compaq will provide notice of the
completion/availability of any necessary patches through AES services (DIA,
DSNlink FLASH and posted to the Services WEB page) and be available from your
normal Compaq Services Support channel.

COMPAQ COMPUTER CORPORATION 9/99
----------------------------- ----

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](<mailto:[email protected]?Subject=VU%2316532 Feedback>).

Data General __ Unknown

Updated: January 28, 2001

Status

Unknown

Vendor Statement

We are investigating. We will provide an update when our investigation is complete.

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](<mailto:[email protected]?Subject=VU%2316532 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.isc.org/products/BIND/bind-security-19991108.html&gt;
• <http://www.redhat.com/support/errata/RHSA1999054-01.html&gt;
• <http://www.debian.org/security/1999/19991116&gt;
• <ftp://ftp.sco.com/SSE/sse033.ltr&gt;
• <http://www.securityfocus.com/vdb/bottom.html?vid=788&gt;

Acknowledgements

Our thanks to ISC for assistance in understanding this vulnerability.

This document was written by Shawn V Hernan.

Other Information

CVE IDs:	CVE-1999-0833
CERT Advisory:	CA-1999-14 Severity Metric: