Vulnerability Note VU#776781

tcpdump vulnerable to buffer overflow via parsing of AFS ACL packets

Overview

Tcpdump version 3.5 contains a buffer overflow vulnerability permitting unauthorized remote root access.

I. Description

Tcpdump version 3.5 added support for handling AFS packets. Unfortunately the code responsible for printing AFS access control lists contains an unchecked buffer that can be overflowed by a remote attacker by sending a crafted AFS packet into the target network. Any machine on the target network that is running tcpdump with a large (> ~500) snaplen argument when the hostile packet arrives can be made to execute arbitrary code. Since tcpdump requires root privileges in order to run, the arbitrary code will also run with root privileges. Fixed in version 3.6.1.

Note that a program that successfully exploits this vulnerability was publicly released on the BugTraq mailing list on January 11, 2001.

II. Impact

Attackers can remotely execute arbitrary code with root privileges on a vulnerable host.

III. Solution

Upgrade to version 3.6.1 or greater.

Filter incoming dst UDP 7000 packets from untrusted networks. Exclude dst UDP 7000 packets from tcpdump capture, e.g. "tcpdump not udp dst port 7000".

Systems Affected

Vendor	Status	Date Notified	Date Updated
FreeBSD.org	Vulnerable	21-Jun-2001
MandrakeSoft	Vulnerable	21-Jun-2001

References

http://www.securityfocus.com/bid/1870
http://www.securityfocus.com/templates/archive.pike?list=1&mid=155883

Credit

First public disclosure by zhodiac@outlimit.org and the !Hispahack Research Team.

Other Information

Date Public:	2001-01-11
Date First Published:	2001-06-22
Date Last Updated:	2001-06-26
CERT Advisory:
CVE-ID(s):	CVE-2000-1026
NVD-ID(s):	CVE-2000-1026
US-CERT Technical Alerts:
Metric:	16.03
Document Revision:	16

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