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============================================================================= FreeBSD-SA-02:28.resolv Security Advisory The FreeBSD Project
Topic: buffer overflow in resolver
Category: core Module: libc Announced: 2002-06-26 Credits: Joost Pol <firstname.lastname@example.org> Affects: All releases prior to and including 4.6-RELEASE Corrected: 2002-06-26 06:34:18 UTC (RELENG_4) 2002-06-26 08:44:24 UTC (RELENG_4_6) 2002-06-26 18:53:20 UTC (RELENG_4_5) FreeBSD only: NO
The resolver implements functions for making, sending and interpreting query and reply messages with Internet domain name servers. Hostnames, IP addresses, and other information are queried using the resolver.
II. Problem Description
DNS messages have specific byte alignment requirements, resulting in padding in messages. In a few instances in the resolver code, this padding is not taken into account when computing available buffer space. As a result, the parsing of a DNS message may result in a buffer overrun of up to a few bytes for each record included in the message.
An attacker (either a malicious domain name server or an agent that can spoof DNS messages) may produce a specially crafted DNS message that will exploit this bug when parsed by an application using the resolver. It may be possible for such an exploit to result in the execution of arbitrary code with the privileges of the resolver-using application. Though no exploits are known to exist today, since practically all Internet applications utilize the resolver, the severity of this issue is high.
There is currently no workaround.
Do one of the following:
1) Upgrade your vulnerable system to 4.6-STABLE; or to the RELENG_4_6 or RELENG_4_5 security branch dated after the correction date (4.6-RELEASE-p1 or 4.5-RELEASE-p7).
2) To patch your present system:
The following patch has been verified to apply to FreeBSD 4.5 and FreeBSD 4.6 systems.
a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility.
b) Execute the following commands as root:
c) Recompile the operating systems as described in <URL:http://www.freebsd.org/doc/handbook/makeworld.html>.
Note that any statically linked applications that are not part of the base system (i.e. from the Ports Collection or other 3rd-party sources) must be recompiled.
VI. Correction details
The following list contains the revision numbers of each file that was corrected in FreeBSD.
Path Revision Branch
src/lib/libc/net/gethostbydns.c RELENG_4 220.127.116.11 RELENG_4_6 18.104.22.168 RELENG_4_5 22.214.171.124 src/lib/libc/net/getnetbydns.c RELENG_4 126.96.36.199 RELENG_4_6 188.8.131.52.8.1 RELENG_4_5 184.108.40.206.6.1 src/lib/libc/net/name6.c RELENG_4 220.127.116.11 RELENG_4_6 18.104.22.168.8.1 RELENG_4_5 22.214.171.124.6.1 src/sys/conf/newvers.sh RELENG_4_6 126.96.36.199.2.2 RELENG_4_5 188.8.131.52.2.8
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