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Re: recent breakins and things to look out for
- From: "Mark Thompson" <mthompson ed umuc edu>
- To: pam-list redhat com, redhat-install-list redhat com
- Subject: Re: recent breakins and things to look out for
- Date: Mon, 01 May 2000 11:14:34 +0200
In case anyone hasn't seen it, there is a serious security vulnerablility in
named. I personally know somebody who was hacked using this method. Named is
often installed as a default, so even if you are not running DNS services, it
would be a good idea to check if named is running. This hack gives the user
root access to your system. Here is the CERT Advisory that was sent out.
CERT Advisory CA-2000-03
Wed, 26 Apr 2000 15:30:02 -0400 (EDT)
CERT Advisory <cert-advisory cert org>
cert-advisory-request cert org
CERT(R) Coordination Center - +1 412-268-7090
cert-advisory cert org
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CERT(r) Advisory CA-2000-03 Continuing Compromises of DNS servers
Original release date: April 26, 2000
Last revised: April 26, 2000
* Systems running various vulnerable versions of BIND (including on
machines where the system administrator does not realize a DNS
server is running)
This CERT Advisory addresses continuing compromises of machines
running the Domain Name System (DNS) server software that is part of
BIND ("named"), including compromises of machines that are not being
used as DNS Servers. The Advisory also reports that a significant
number of delegated(*) DNS servers in the in-addr.arpa tree are running
outdated versions of DNS software, and urges system and network
administrators to ensure that they are up-to-date with DNS security
patches and workarounds.
The CERT Coordination Center has received reports of continuing
activity indicating that intruders are targeting machines running
vulnerable versions of "named" . We continue to receive regular, daily
reports that sites running unpatched, vulnerable versions of "named"
have been compromised. CERT Advisory CA-99-14 "Multiple
Vulnerabilities in BIND" describes the BIND NXT record privileged
compromise vulnerability that is being exploited. We encourage you to
review this advisory and to apply the appropriate patches if you have
not done so already. The advisory is available at
Some sites with compromised systems have found one of the following
empty directories on systems where the NXT record vulnerability was
Other artifacts that are commonly found include
* inetd started with an intruder-supplied configuration file in /tmp
that provides a backdoor into the system
* modified /etc/inittab and/or system startup files to load intruder
processes at boot time
* Trojan horse versions of sshd and /bin/login designed to provide a
backdoor into a compromised system
* complete rootkits that include Trojan horse replacements for
system binaries, sniffers, denial-of-service tools, vulnerability
scanners, exploits, etc.
* newer versions of BIND
Compromised systems are commonly used to search for and attack other
potentially vulnerable systems.
In many of the reports of DNS server compromises, compromised machines
running DNS server software were not being used as DNS servers. The
DNS server software was running because it was installed by default
(unknowingly in many cases) when the machines were configured. This
software was not up to date with security patches and workarounds; and
since the system administrators were not planning to have the machines
operate as DNS servers, they did not ensure the software was up to
date, or simply disable the DNS server software on the machine. We
encourage system and network administrators to disable DNS server
software, and other services, on machines where the services are not
We have also received information from Bill Manning of the USC/ISI
concerning DNS servers running vulnerable versions of domain name
server software. Since 1997, Bill Manning sweeps the inverse tree
(in-addr.arpa) on a quarterly basis to verify the accuracy of
delegations within that hierarchy. Using the first quarter survey
results, he compiled a list of what version of DNS server software
the servers were running. Of the responding DNS servers that are
delegated(*) DNS servers for the in-addr.arpa zone, more than 50%
of these DNS servers were running older, vulnerable versions of
BIND (any vulnerabilities, not just the NXT vulnerability). This is
significant because the compromise of DNS servers that are
delegated DNS servers can have impact on the security of other
organizations in addition to the organization operating the DNS
A copy of the survey results are available at
Based on the number of older versions being run, and the rate of
compromises, we believe the number of DNS servers running older,
vulnerable versions of BIND have not significantly decreased since the
survey was published.
We encourage DNS server operators to ensure that their DNS server
software is up to date with the most recent versions of the DNS server
software and that all security patches and workarounds have been
delegated DNS server: a delegated DNS is a DNS server that is assigned
responsibility for responding to requests for a portion of the DNS
hierarchy. For more information on delegation, see the section on
delegation in DNS and BIND third edition, by Paul Albitz and Cricket
Liu, O'Reilly and Associates, 1998.
Advisory Author: Jeffrey J. Carpenter
The CERT Coordination Center thanks Bill Manning, USC/ISI, for
providing information used in this CERT Advisory.
This document is available from:
CERT/CC Contact Information
Email: cert cert org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
CERT personnel answer the hotline 08:00-20:00 EST(GMT-5) / EDT(GMT-4)
Monday through Friday; they are on call for emergencies during other
hours, on U.S. holidays, and on weekends.
We strongly urge you to encrypt sensitive information sent by email.
Our public PGP key is available from
If you prefer to use DES, please call the CERT hotline for more
Getting security information
CERT publications and other security information are available from
our web site
To be added to our mailing list for advisories and bulletins, send
email to cert-advisory-request cert org and include SUBSCRIBE
your-email-address in the subject of your message.
* "CERT" and "CERT Coordination Center" are registered in the U.S.
Patent and Trademark Office.
Any material furnished by Carnegie Mellon University and the Software
Engineering Institute is furnished on an "as is" basis. Carnegie
Mellon University makes no warranties of any kind, either expressed or
implied as to any matter including, but not limited to, warranty of
fitness for a particular purpose or merchantability, exclusivity or
results obtained from use of the material. Carnegie Mellon University
does not make any warranty of any kind with respect to freedom from
patent, trademark, or copyright infringement.
Copyright 2000 Carnegie Mellon University.
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> On Wed, Apr 26, 2000 at 11:09:22AM -0700, Andrew Morgan wrote:
> > [In the majority of cases that I was able to follow up with, this was
> > related to a malicious attack: /bin/login and /usr/bin/passwd were
> > replaced with 'intruder friendly ones'.
> I investigated such a break-in a couple of days ago on an OpenLinux
> box. It appears that the intruders did not alter the RPM package database
> so it was quite simple to pin down what files got changed. I cannot
> tell exactly because the machine's owner had already partly restored
> it. I did however notice that login had been replaced, as well as
> crond and crontab. The attackers did leave parts of an intrusion kit
> in some subdirectory of /dev.
> During an earlier attack on that machine, attackers had also installed
> a network sniffer as /usr/sbin/rpc.nlsd, that was writing its log
> info to another subdirectory of /dev.
> > My advice so far has been and will continue
> > to be "reinstall your system from CD and be sure to install all of the
> > available updates", but this is not always well received.]
> That's my advice as well.
> Olaf Kirch | --- o --- Nous sommes du soleil we love when we play
> okir monad swb de | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax
> okir caldera de +-------------------- Why Not?! -----------------------
> UNIX, n.: Spanish manufacturer of fire extinguishers.
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