From [log in to unmask] Fri Jul 20 14:25:57 2001
Date: Fri, 20 Jul 2001 10:04:23 +0200
From: [log in to unmask]
Reply-To: SECURITY Informations-Liste <[log in to unmask]>
To: [log in to unmask]
Subject: [Advisory] "Code Red" Wurm nutzt Schwachstelle in MS IIS -
CA-2001-19
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Liebe Kolleginnen und Kollegen,
soeben erreichte uns nachfolgendes Advisory des CERT Coordination
Centers. Wir geben diese Informationen unveraendert an Sie weiter.
In dem Advisory wird der "Code Red" Wurm beschrieben, der einen Buffer
Overflow Fehler in der MS IIS Indexing Service DLL ausnutzt, um
Internet Server zu kompromittieren und sich dadurch weiter zu
verbreiten. Weitere Informationen ueber die vom Wurm ausgenutzte
Schwachstelle im IIS finden in den Advisories von Microsoft
(MS01-033).
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp
und vom CERT/CC (CA-2001-13)
http://www.cert.org/advisories/CA-2001-13.html
Weitere Informationen zu dem Wurm finden Sie in einer ausfuehrlichen
Analyse von eEye Digital Security
http://www.eeye.com.
Die Vorgehensweise des Wurms ist wie folgt:
- - Nach einem TCP Portscan gegen Port 80 sendet der angreifende
Rechner eine speziell konstruierte HTTP GET Anfrage, die den in den
Advisories MS01-033 von Microsoft und CA-2001-13 vom CERT/CC
beschriebenen Buffer Overflow Fehler im IIS ausnutzt.
- - ist der Exploit erfolgreich verlaufen, sucht der Wurm nach der
Existenz der Datei c:\notworm. Ist diese Datei vorhanden, bricht der
Wurm seine Ausfuehrung ab.
- - Ist diese Datei nicht vorhanden, beginnt der Wurm TCP Port 80 von
zufaelligen IP Adressen zu scannen, um weitere angreifbare Internet
Server zu finden und sich weiter zu verbreiten.
- - findet der Wurm eine englische (US) Windows 2000/NT Installation
vor, beginnt der Wurm die lokalen Web Seiten zu veraendern
(Text: HELLO! Welcome to http://www.worm.com! Hacked By Chinese!)
Einen Angriff ausgehend von dem "code red" Wurm erkennen Sie an dem
HTTP GET Request, der den Fingerprint darstellt:
/default.ida?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNN%u9090%u6858%ucbd3%u7801%u9090%u6858%ucbd3%
u7801%u9090%u6858%ucbd3%u7801%u9090%u9090%u8190%u00c3%u0003%u8b00%u531
b%u53ff%u0078%u0000%u00=a
Kompromittierte Rechner erkennen Sie an Portscans von TCP Port 80
von zufaelligen IP Adressen ausgehend von Ihrem Internet
Server. Beachten Sie bitte, dass eine erfolgreiche Kompromittierung
keine Spuren in den IIS Logs hinterlaesst und auch keine Veraenderung
von Web Seiten erfolgen braucht (wenn der Wurm keine englische (US)
Windows 2000/NT Installation vorfindet.) (siehe Analyse)
Da alle kompromittierten Rechner jeweils identische IP Adressen
scannen, werden nicht kompromittierte Rechner von jedem
kompromittierten Rechner aus gescannt - was dem Effekt eines DDoS
Angriffes nahekommen kann. Weiterhin kann ein Angreifer beliebige
Befehle in dem Local System security Kontext ausfuehren.
Von der Schwachstelle betroffen sind Microsoft Windows NT 4.0 und
Windows 2000 mit IIS 4.0 oder IIS 5.0.
Wir empfehlen Ihnen dringend, den entsprechenden Patch von Microsoft
zu installieren. Das DFN-CERT bietet einen Mirror der Inhalte des
FTP-Servers von Microsoft mit den dort bereitgestellten Patches fuer
die us- amerikanische und deutsche Sprachversion von Microsoft Windows
NT 4.0 und des Internet Explorers unter
ftp://ftp.cert.dfn.de/pub/vendor/microsoft/
an. Des weiteren finden Sie dort die aktuellen Service-Packs (deutsch
und us-amerikanisch) fuer Windows NT 4.0 und die aktuellen Patches
fuer Windows 2000 (deutsch und us-amerikanisch).
Die in diesem Advisory beschriebenen Patches finden Sie unter
ftp://ftp.cert.dfn.de/pub/vendor/microsoft/winnt/Security_Bulletins/
sowie
ftp://ftp.cert.dfn.de/pub/vendor/microsoft/win2000/Security_Bulletins/
(siehe jeweils die Datei 01-README)
Mit freundlichen Gruessen,
Jan Kohlrausch, DFN-CERT
- --
Jan Kohlrausch | mailto:[log in to unmask]
DFN-CERT GmbH | http://www.cert.dfn.de/team/kohlrausch/
Oberstr. 14b. | Phone: +49(40) 808077 555
D-20144 Hamburg | FAX: +49(40) 808077 556
Germany | PGP-Key: finger [log in to unmask]
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CERT Advisory CA-2001-19 "Code Red" Worm Exploiting Buffer Overflow In IIS
Indexing Service DLL
Original release date: July 19, 2001
Source: CERT/CC
A complete revision history can be found at the end of this file.
Systems Affected
Systems running Microsoft Windows NT 4.0 and Windows 2000 with IIS 4.0
or IIS 5.0 enabled
Overview
The CERT/CC has received reports of new self-propagating malicious
code that exploits certain configurations of Microsoft Windows
susceptible to the vulnerability described in CERT advisory CA-2001-13
Buffer Overflow In IIS Indexing Service DLL. These reports indicate
that the "Code Red" worm may have already affected as many as 225,000
hosts, and continues to spread rapidly.
Description
In examples we have seen, the "Code Red" worm attack proceeds as
follows:
* The victim host is scanned for TCP port 80 by the "Code Red" worm.
* The attacking host sends a crafted HTTP GET request to the victim,
attempting to exploit a buffer overflow in the Indexing Service
described in CERT advisory CA-2001-13
* If the exploit is successful, the worm begins executing on the
victim host. Initially, the existence of the c:\notworm file is
checked. Should this file be found, the worm ceases execution.
* If c:\notworm is not found, the worm begins spawning threads to
scan seemingly random IP addresses for hosts listening on TCP port
80, exploiting any vulnerable hosts it finds.
* If the victim host's default language is English, then after 100
scanning threads have started and a certain period of time has
elapsed following infection, all web pages served by the victim
host are defaced with the message
HELLO! Welcome to http://www.worm.com! Hacked By Chinese!
* If the victim host's default language is not English, the worm
will continue scanning but no defacement will occur.
System Footprint
The "Code Red" worm can be identified on victim machines by the
presence of the following string in IIS log files:
/default.ida?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNN%u9090%u6858%ucbd3%u7801%u9090%u6858%ucbd3%
u7801%u9090%u6858%ucbd3%u7801%u9090%u9090%u8190%u00c3%u0003%u8b00%u531
b%u53ff%u0078%u0000%u00=a
Additionally, web pages on victim machines may be defaced with the
following message:
HELLO! Welcome to http://www.worm.com! Hacked By Chinese!
The text of this page is stored exclusively in memory and is not
written to disk. Therefore, searching for the text of this page in the
file system may not detect compromise.
Network Footprint
A host running an active instance of the "Code Red" worm scans random
IP addresses on port 80/TCP looking for other hosts to infect.
Additional detailed analysis of this worm has been published by eEye
Digital Security at http://www.eeye.com.
Impact
In addition to web site defacement, infected systems may experience
performance degradation as a result of the scanning activity of this
worm.
Non-compromised systems and networks that are being scanned by other
hosts infected by the "Code Red" worm may experience severe denial of
service. This occurs because each instance of the "Code Red" worm uses
the same random number generator seed to create the list of IP
addresses it scans. Therefore, all victim hosts scan the same IP
addresses.
Furthermore, it is important to note that while the "Code Red" worm
appears to merely deface web pages on affected systems and attack
other systems, the IIS indexing vulnerability it exploits can be used
to execute arbitrary code in the Local System security context. This
level of privilege effectively gives an attacker complete control of
the victim system.
Solutions
The CERT/CC encourages all Internet sites to review CERT advisory
CA-2001-13 and ensure workarounds or patches have been applied on all
affected hosts on your network.
If you believe a host under your control has been compromised, you may
wish to refer to
http://www.cert.org/tech_tips/win-UNIX-system_compromise.html
Reporting
The CERT/CC is interested in receiving reports of this activity. If
machines under your administrative control are compromised, please
send mail to [log in to unmask] with the following text included in the
subject line: "[CERT#36881]".
______________________________________________________________________
Author(s): Roman Danyliw and Allen Householder
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2001-19.html
______________________________________________________________________
CERT/CC Contact Information
Email: [log in to unmask]
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT 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.
Using encryption
We strongly urge you to encrypt sensitive information sent by email.
Our public PGP key is available from
http://www.cert.org/CERT_PGP.key
If you prefer to use DES, please call the CERT hotline for more
information.
Getting security information
CERT publications and other security information are available from
our web site
http://www.cert.org/
To subscribe to the CERT mailing list for advisories and bulletins,
send email to [log in to unmask] Please include in the body of your
message
subscribe cert-advisory
* "CERT" and "CERT Coordination Center" are registered in the U.S.
Patent and Trademark Office.
______________________________________________________________________
NO WARRANTY
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.
Revision History
Jul 19, 2001: Initial release
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