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             AUSCERT External Security Bulletin Redistribution

           ESB-2003.0579 -- Trend Micro Medium Risk Virus Alert
                  WORM_MSBLAST.D (W32/Welchia, W32/Nachi)
                              19 August 2003

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        AusCERT Security Bulletin Summary
        ---------------------------------

Operating System:       Microsoft Windows Server 2003
                        Microsoft Windows XP
                        Microsoft Windows 2000
                        Microsoft Windows NT 4.0
Impact:                 Execute Arbitrary Code/Commands
                        Delete Arbitrary Files
Access Required:        Remote
CVE Names:              CAN-2003-0352, CAN-2003-0109

Ref:                    AU-2003.011
                        AU-2003.010
                        AL-2003.11
                        AL-2003.02
                        ESB-2003.0561
                        ESB-2003.0525
                        ESB-2003.0313

Comment: For more information, please see:

         http://www.ocipep.gc.ca/opsprods/alerts/AL03-007b_e.asp
         http://www.cert.org/current/current_activity.html#welchia
         http://xforce.iss.net/xforce/alerts/id/150
         http://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM_MSBLAST.D
         http://vil.nai.com/vil/content/v_100559.htm
         http://www3.ca.com/virusinfo/virus.aspx?ID=36372
         http://www.f-secure.com/v-descs/welchi.shtml
         http://us.mcafee.com/virusInfo/default.asp?id=nachi
         http://www.sophos.com/virusinfo/analyses/w32nachia.html
         http://securityresponse.symantec.com/avcenter/venc/data/w32.welchia.worm.html

         This new variant exploits specifically targets Windows XP with
         the original DCOM RPC vulnerability (that Blaster also targeted
         per AU-2003.011) via TCP port 135. In addition, the worm also
         targets computers running Microsoft IIS 5.0 with the previous
         WebDav vulnerability (described in AL-2003.02) via TCP port 80.
         Reports to AusCERT indicate that the greatest impact of this
         worm is the denial-of-service condition that occurs within
         organisations due to high levels of ICMP traffic the worm
         generates to find active machines to infect.

         AusCERT has published an article "Protecting your computer from
         malicious code" which provides advice for protecting the PC desk
         top environment from malicious code for home users, SMEs or
         large organisations:

         http://www.auscert.org.au/3352

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TrendLabs HQ received numerous infection reports of a new malware named WORM_MSBLAST.D
spreading in Japan, Taiwan, and Singapore. It currently has an infection count of 20,000.
A yellow alert has been called at 7:14 AM, August 18, 2003 (US Pacific Time) 
to stop the spread of this malware.

It usually arrives as DLLHOST.EXE (~10,240 bytes) and opens port 707, for its malicious routines. Similar to 
the earlier MSBLAST worm variants, this malware also exploits the RPC DCOM Buffer Overflow, 
and instructs target systems to download its copy from the affected system using the TFTP program. 


TrendLabs HQ has released the following EPS deliverables:
- -	TMCM Outbreak Prevention Policy 47
- -	Official Pattern Release 614	
- -	Damage Cleanup Template 161



Please inform us if there are any infection reports in your region.

For more information on WORM_MSBLAST.D please visit our Web site at:
http://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM_MSBLAST.D
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