Security update for tcpdump

Knowledgebase

(Last modified: 22MAY2002)

solutions Security update for tcpdump SuSE Linux Maintenance Web (586b4b4feec098dbf0e83ed48fa7ab77)

Applies to

Product(s): SuSE Linux Database Server
SuSE Linux Admin-CD for Firewall
SuSE eMail Server III

SuSE Linux Enterprise Server 7 for IA32
SuSE Linux Enterprise Server 7 for IA64
SuSE Linux Enterprise Server 7 for S/390 and zSeries
SuSE Linux Enterprise Server for S/390
SuSE Firewall Adminhost VPN
SuSE Linux Connectivity Server

Package: tcpdump
libpcapn
Release: 20020522
Obsoletes: none

Indications

Everyone using tcpdump should install this patch.

Contraindications

None.

Problem description

Tcpdump is a command-line tool for monitoring network traffic. It uses libpcap, a library which provides a portable framework for low-level network monitoring. Both are developed by the same team.
During internal source code auditing done by FreeBSD, several overflowable buffers were discovered in the version of tcpdump included in many OS'. Some simply allow the remote attacker to crash the local tcpdump process. This is a problem for systems using tcpdump as a form of intrusion detection, as after an attacker has crashed the tcpdump process, network activity will no longer occur and may be able to cause arbitrary code to be executed as the user running tcpdump, often root.
There is a more serious vulnerability in the decoding of AFS ACL packets in tcpdump which may allow a remote attacker to execute arbitrary code on the local system (usually at root privilege, since root privilege is required to run tcpdump). Similar problem is in displaying NFS traffic, when tcpdump reliably segfaults.
Last problem is in using kernel filter: This issue occurs due to the
interaction in libpcap and the kernel implementation of
filters. When a PF_PACKET socket is created, it is bound into
the network and starts receiving packets. Packets are placed upon its
queue for pickup via recvfrom(). libpcap then binds
the socket to an interface, and then sets the filter on the socket. None
of these actions call skb_queue_purge(), which means that
packets that were put in the queue before the filter was set remain in
the queue and are picked up by libpcap, and hence
tcpdump.

Solution

Please install the updates provided at the location noted below.

Installation notes

This update is provided as an RPM package that can easily be installed onto a running system by using this command:
rpm -Uvh libpcapn.rpm tcpdump.rpm

links to download packages

Download Source Packages

Download the source code of the patches for maintained products.

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