SuSE: 2008-033: bind Security Update
Summary
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SUSE Security Announcement
Package: bind
Announcement ID: SUSE-SA:2008:033
Date: Fri, 11 Jul 2008 09:00:00 +0000
Affected Products: openSUSE 10.2
openSUSE 10.3
openSUSE 11.0
SUSE SLES 9
Novell Linux Desktop 9
Open Enterprise Server
Novell Linux POS 9
SUSE Linux Enterprise Desktop 10 SP1
SLE SDK 10 SP1
SLE SDK 10 SP2
SUSE Linux Enterprise Server 10 SP1
SUSE Linux Enterprise Desktop 10 SP2
SUSE Linux Enterprise Server 10 SP2
Vulnerability Type: DNS cache poisoning
Severity (1-10): 9
SUSE Default Package: no
Cross-References: CVE-2008-1447
Content of This Advisory:
1) Security Vulnerability Resolved:
DNS cache poisoning
2) Solution or Work-Around
3) Special Instructions and Notes
4) Package Location and Checksums
5) Pending Vulnerabilities, Solutions, and Work-Arounds:
6) Authenticity Verification and Additional Information
______________________________________________________________________________
1) Problem Description and Brief Discussion
The bind daemon is responsible for resolving hostnames in IP addresses and
vice versa.
The new version of bind uses a random transaction-ID (TRXID) and a random
UDP source-port for DNS queries to address DNS cache poisoning attacks
possible because of the "birthday paradox" and an attack discovered by Dan
Kaminsky. Unfortunately we do not have details about Kaminsky's attack and
have to trust the statement that a random UDP source-port is sufficient to
stop it.
DNS servers that do not support recursive queries or do not use a cache
(authoritative only servers) are not vulnerable too.
Update packages of bind9 for SLES8 will be available soon.
The glibc stub resolver is known to be vulnerable too and we will publish
updates as soon as possible.
Note, a local attacker can always sniff DNS queries and generate spoofed
responses easily.
If you use the UDP source-port number of the DNS server in your firewall
configuration, for example to let DNS queries through your packetfilter,
then you have to take steps to adapt your filter rules to the new behavior
of the DNS server.
2) Solution or Work-Around
To protect your infrastructure from cache poisoning attacks you should
provide two DNS servers.
One that is authoritative only and accessible from the Internet to resolve
queries for your local systems that are available over the Internet. The
other system (caching) is not accessible over the Internet and can be used
by internal clients to recursively lookup names and addresses.
But we encourage you to install the bind update as soon as possible too.
If you use the latest update of pdns-recursor you are not vulnerable to
this attack.
For the glibc stub resolver bug you can install a local secure DNS for-
warder on your machine or make a DNS forwarder available for a protected
network.
3) Special Instructions and Notes
Please restart the bind daemon after the update.
4) Package Location and Checksums
The preferred method for installing security updates is to use the YaST
Online Update (YOU) tool. YOU detects which updates are required and
automatically performs the necessary steps to verify and install them.
Alternatively, download the update packages for your distribution manually
and verify their integrity by the methods listed in Section 6 of this
announcement. Then install the packages using the command
rpm -Fhv
References