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 -----BEGIN PGP SIGNED MESSAGE----- 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] - -----BEGIN PGP SIGNED MESSAGE----- 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. 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