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Security Alert: BIND9 DNS Cache Poisoning Bug

An unpatched security hole in BIND 9 package could be used by attackers to poison your DNS cache. Attacker to take control of all hosted domains and can can lead to misdirected web traffic and email rerouting.

This update changes Debian's BIND 9 packages to implement the recommended countermeasure: UDP query source port randomization. This change increases the size of the space from which an attacker has to guess values in a backwards-compatible fashion and makes successful attacks significantly more difficult.

Details

  • Package : bind9
  • Vulnerability : DNS cache poisoning
  • Problem type : remote
  • Debian-specific: no
  • CVE Id(s) : CVE-2008-1447
  • CERT advisory : VU#800113

How do I fix BIND9 bug under Debian Linux?

Install the BIND 9 upgrade, using following commands, enter:
# apt-get update
# apt-get install bind9

Sample output:

Reading package lists... Done
Building dependency tree... Done
The following extra packages will be installed:
  libdns22 libisc11 libisccc0 libisccfg1
Suggested packages:
  bind9-doc
The following packages will be upgraded:
  bind9 libdns22 libisc11 libisccc0 libisccfg1
5 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
Need to get 1267kB of archives.
After unpacking 4096B disk space will be freed.
Do you want to continue [Y/n]? y
Get:1 http://security.debian.org stable/updates/main bind9 1:9.3.4-2etch3 [319kB]
Get:2 http://security.debian.org stable/updates/main libisc11 1:9.3.4-2etch3 [188kB]
Get:3 http://security.debian.org stable/updates/main libisccc0 1:9.3.4-2etch3 [96.7kB]
Get:4 http://security.debian.org stable/updates/main libisccfg1 1:9.3.4-2etch3 [111kB]
Get:5 http://security.debian.org stable/updates/main libdns22 1:9.3.4-2etch3 [552kB]
Fetched 1267kB in 1s (724kB/s)
Reading changelogs... Done
(Reading database ... 27244 files and directories currently installed.)
Preparing to replace bind9 1:9.3.4-2etch1 (using .../bind9_1%3a9.3.4-2etch3_amd64.deb) ...
Stopping domain name service...: bind.
Unpacking replacement bind9 ...
Preparing to replace libisc11 1:9.3.4-2etch1 (using .../libisc11_1%3a9.3.4-2etch3_amd64.deb) ...
Unpacking replacement libisc11 ...
Preparing to replace libisccc0 1:9.3.4-2etch1 (using .../libisccc0_1%3a9.3.4-2etch3_amd64.deb) ...
Unpacking replacement libisccc0 ...
Preparing to replace libisccfg1 1:9.3.4-2etch1 (using .../libisccfg1_1%3a9.3.4-2etch3_amd64.deb) ...
Unpacking replacement libisccfg1 ...
Preparing to replace libdns22 1:9.3.4-2etch1 (using .../libdns22_1%3a9.3.4-2etch3_amd64.deb) ...
Unpacking replacement libdns22 ...
Setting up libisc11 (9.3.4-2etch3) ...
Setting up libdns22 (9.3.4-2etch3) ...
Setting up libisccc0 (9.3.4-2etch3) ...
Setting up libisccfg1 (9.3.4-2etch3) ...
Setting up bind9 (9.3.4-2etch3) ...
Configuration file `/etc/bind/db.root'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : background this process to examine the situation
 The default action is to keep your current version.
*** db.root (Y/I/N/O/D/Z) [default=N] ? y
Installing new version of config file /etc/bind/db.root ...
Starting domain name service...: bind.

Also, verify that source port randomization is active. Check that the /var/log/daemon.log file does not contain messages of the following form:

 named[6106]: /etc/bind/named.conf.options:28: using specific
    query-source port suppresses port randomization and can be insecure.

If you see message replace replace the port numbers contained within them with "*" sign (e.g.,
replace "port 53" with "port *") in /etc/bind/named.conf.option file.

How do I fix this issue under Red Hat Linux / RHEL ?

Simply type the command, enter:
# yum update

RIP: BIND 8 under Debian 4.x

Debian team also posted BIND 8 deprecation notice. From the announcement:

The BIND 8 legacy code base could not be updated to include the recommended countermeasure (source port randomization, see DSA-1603-1 for details). There are two ways to deal with this situation:

1. Upgrade to BIND 9 (or another implementation with source port randomization). The documentation included with BIND 9 contains a migration guide.

2. Configure the BIND 8 resolver to forward queries to a BIND 9 resolver. Provided that the network between both resolvers is trusted, this protects the BIND 8 resolver from cache poisoning attacks (to the same degree that the BIND 9 resolver is protected).

This problem does not apply to BIND 8 when used exclusively as an authoritative DNS server. It is theoretically possible to safely use BIND 8 in this way, but updating to BIND 9 is strongly recommended.
BIND 8 (that is, the bind package) will be removed from the etch distribution in a future point release.

By default Apache webserver listen on port 80 (http) and port 443 (https i.e. secure http). Apache webserver uses the TCP protocol to transfer information/data between server and browser. The default Iptables configuration does not allow inbound access to the HTTP (80) and HTTPS (443) ports used by the web server. This post explains how to allow inbound and outbound access to web services under Linux.
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