As of April 28, 2004, due to a decreased rate of submissions, Symantec Security Response has downgraded this threat to a Category 2 from a Category 3.
W32.Welchia.B.Worm is a variant of W32.Welchia.Worm
. If the version of the operating system of the infected machine is Chinese (Simplified), Chinese (Traditional), Korean, or English, the worm will attempt to download the Microsoft Workstation Service Buffer Overrun
and Microsoft Messenger Service Buffer Overrun
patches from the Microsoft® Windows Update Web site, install it, and then restart the computer.
The worm also attempts to remove the W32.Mydoom.A@mm
W32.Welchia.B.Worm exploits multiple vulnerabilities, including:
The presence of the file, %Windir%\system32\drivers\svchost.exe, is an indication of a possible infection.
This threat is compressed with UPX.
Virus definitions dated February 11, 2004 revision 23 (20040211.023 or Defs Version 60211w) or later will detect this threat.
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