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AUSCERT External Security Bulletin Redistribution
ESB-2001.491 -- CERT Summary CS-2001-04
21 November 2001
AusCERT Security Bulletin Summary
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CERT Summary CS-2001-04
November 20, 2001
Each quarter, the CERT Coordination Center (CERT/CC) issues the CERT
Summary to draw attention to the types of attacks reported to our
incident response team, as well as other noteworthy incident and
vulnerability information. The summary includes pointers to sources of
information for dealing with the problems.
Past CERT summaries are available from:
Since the last regularly scheduled CERT summary, issued in August 2001
(CS-2001-03), we have seen a new worm known as "Nimda," as well as
active exploitation of a vulnerability in Microsft DNS servers. In
addition, we have published a paper on denial of service trends,
issued a new PGP key, and updated the UNIX Security Checklist.
For more current information on activity being reported to the
CERT/CC, please visit the CERT/CC Current Activity page. The Current
Activity page is a regularly updated summary of the most frequent,
high-impact types of security incidents and vulnerabilities being
reported to the CERT/CC. The information on the Current Activity page
is reviewed and updated as reporting trends change.
CERT/CC Current Activity
1. W32/Nimda Worm
Over the past several months, we have received reports of
malicious code known as the "W32/Nimda Worm." This worm can
propogate itself via several methods, including email, network
shares, or by visiting an infected web site. On September 18, the
CERT/CC issued an advisory on Nimda.
CERT Advisory CA-2001-26: Nimda Worm
2. Exploitation of Vulnerability in
SSH1 CRC-32 Compensation Attack Detector
The CERT/CC has received multiple reports of systems being
compromised via the CRC-32 compensation attack detector
vulnerability (VU#945216). On November 5, the CERT/CC released an
incident note which describes system compromises via a
vulnerability in the SSH1 (Secure Shell Protocol v1) CRC-32 attack
detection code. Consequentially, we are also receiving reports of
increased scanning activity for the SSH service (22/tcp).
Incident Note IN 2001-12: Exploitation of vulnerability
in SSH1 CRC-32 compensation attack detector
Vulnerability Note #945216: SSH CRC32 attack detection
code contains remote integer overflow
3. DNS Cache Poisoning in Microsoft DNS Servers
The CERT/CC has received reports from sites experiencing cache
corruption on systems running Microsoft DNS Server. We issued an
incident note which describes this corruption and its impact on
systems. The default configuration of this software allows data
from malicious or incorrectly configured DNS servers to be cached
by a Microsoft DNS server. This corruption can result in erroneous
DNS information being returned to clients which use this server.
Incident Note IN-2001-11: Cache Corruption on Microsoft
Vulnerability Note #109475: Microsoft Windows NT and 2000
Domain Name Servers allow non-authoritative RRs to be
cached by default
4. Trends In Denial Of Service Attack Technology
This paper describes the current and possible future states of
denial of service (DoS) technology. This document is in Adobe
Acrobat format, and requires Acrobat Reader.
Trends In Denial Of Service Attack Technology
UNIX Security Checklist Version 2.0
The CERT Coordination Center and the Australian Computer Emergency
Response Team (AusCERT) have jointly published version 2.0 of the UNIX
Security Checklist which details steps to improve the security of UNIX
Operating Systems. We encourage system administrators to review all
sections of this document and, if appropriate, modify their systems
accordingly to fix potential weaknesses.
AUSCERT UNIX Security Checklist
New CERT/CC PGP Key
On October 1, the CERT/CC issued a new PGP key, which should be used
when sending sensitive information to the CERT/CC.
CERT/CC PGP Public Key
Sending Sensitive Information To The CERT/CC
What's New and Updated
Since the last CERT Summary, we have published new and updated
* Congressional Testimony
* Incident Notes
* CERT/CC Statistics
* Tech Tips
* Training Schedule
* UNIX Security Checklist v2.0
This document is available from:
CERT/CC Contact Information
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/CC personnel answer the hotline 08:00-17:00 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 subscribe to the CERT mailing list for advisories and bulletins,
send email to firstname.lastname@example.org. Please include in the body of your
* "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.
Conditions for use, disclaimers, and sponsorship information
Copyright ©2001 Carnegie Mellon University.
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This security bulletin is provided as a service to AusCERT's members. As
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Previous advisories and external security bulletins can be retrieved from:
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AusCERT personnel answer during Queensland business hours
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On call after hours for emergencies.
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