W32/Mytob-S

Please follow the instructions for removing worms.

W32/Mytob-S is a mass-mailing worm and backdoor Trojan that targets users of Internet Relay Chat programs.

The worm drops the files msdirectx.sys (detected by Sophos's anti-virus products as Troj/NtRootK-F), winsys.exe (detected by Sophos's anti-virus products as Troj/Furoot-B) and coolbot.exe (detected by Sophos's anti-virus products as W32/Mytob-H). Note that W32/Mytob-S uses the filename "coolbot.exe" for both a copy of the original worm in the Windows system folder and as the dropped file in the root folder, though they are different files.

W32/Mytob-S is capable of spreading through email and through various operating system vulnerabilities. W32/Mytob-S is a mass-mailing worm and backdoor Trojan that targets users of Internet Relay Chat programs.

When first run W32/Mytob-S copies itself to the Windows system folder as coolbot.exe and creates the following registry entries:

HKCU\System\CurrentControlSet\Control\Lsa
HELLBOT3
"coolbot.exe"

HKCU\Software\Microsoft\OLE
HELLBOT3
"coolbot.exe"

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
HELLBOT3
"coolbot.exe"

HKLM\Software\Microsoft\Ole
HELLBOT3
"coolbot.exe"

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
HELLBOT3
"coolbot.exe"

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices
HELLBOT3
"coolbot.exe"

HKLM\System\CurrentControlSet\Control\Lsa
HELLBOT3
"coolbot.exe"

W32/Mytob-S copies itself to the root folder as:

eminem vs 2pac.scr
funny pic.scr
photo album.scr

and drops the files msdirectx.sys (detected by Sophos's anti-virus products as Troj/NtRootK-F), winsys.exe (detected by Sophos's anti-virus products as Troj/Furoot-B) and coolbot.exe (detected by Sophos's anti-virus products as W32/Mytob-H). Note that W32/Mytob-S uses the filename "coolbot.exe" for both a copy of the original worm in the Windows system folder and as the dropped file in the root folder, though they are different files.

W32/Mytob-S also appends the following to the HOSTS file to deny access to security related websites:

127.0.0.1 www.symantec.com
127.0.0.1 securityresponse.symantec.com
127.0.0.1 symantec.com
127.0.0.1 www.sophos.com
127.0.0.1 sophos.com
127.0.0.1 www.mcafee.com
127.0.0.1 mcafee.com
127.0.0.1 liveupdate.symantecliveupdate.com
127.0.0.1 www.viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 f-secure.com
127.0.0.1 www.f-secure.com
127.0.0.1 kaspersky.com
127.0.0.1 www.avp.com
127.0.0.1 www.kaspersky.com
127.0.0.1 avp.com
127.0.0.1 www.networkassociates.com
127.0.0.1 networkassociates.com
127.0.0.1 www.ca.com
127.0.0.1 ca.com
127.0.0.1 mast.mcafee.com
127.0.0.1 my-etrust.com
127.0.0.1 www.my-etrust.com
127.0.0.1 download.mcafee.com
127.0.0.1 dispatch.mcafee.com
127.0.0.1 secure.nai.com
127.0.0.1 nai.com
127.0.0.1 www.nai.com
127.0.0.1 update.symantec.com
127.0.0.1 updates.symantec.com
127.0.0.1 us.mcafee.com
127.0.0.1 liveupdate.symantec.com
127.0.0.1 customer.symantec.com
127.0.0.1 rads.mcafee.com
127.0.0.1 trendmicro.com
127.0.0.1 www.microsoft.com
127.0.0.1 www.trendmicro.com

W32/Mytob-S is capable of spreading through email and through various operating system vulnerabilities such as LSASS (MS04-011). Email sent by W32/Mytob-S has the following properties:

Subject line:

Status
Server Report
Mail Transaction Failed
Mail Delivery System
thanks!
read it immediately

Message text:

This is a multi-part message in MIME format

Mail transaction failed. Partial message is available.

The message contains Unicode characters and has been sent as a binary attachment.

The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.

The original message was included as an attachment.

I have received your document. The corrected document is attached.

The attached file consists of a base name followed by the extentions PIF, SCR, EXE or ZIP. The worm may optionally create double extensions where the first extension is DOC, TXT or HTM and the final extension is PIF, SCR, EXE or ZIP.

W32/Mytob-S harvests email addresses from files on the infected computer and from the Windows address book. The worm avoids sending email to address that contain the following:

.gov
.mil
accoun
acketst
admin
anyone
arin.
avp
berkeley
borlan
bsd
bsd
bugs
ca
certific
contact
example
feste
fido
foo.
fsf.
gnu
gold-certs
google
google
gov.
help
iana
ibm.com
icrosof
icrosoft
ietf
info
inpris
isc.o
isi.e
kernel
linux
linux
listserv
math
me
mit.e
mozilla
mydomai
no
nobody
nodomai
noone
not
nothing
ntivi
page
panda
pgp
postmaster
privacy
rating
rfc-ed
ripe.
root
ruslis
samples
secur
sendmail
service
site
soft
somebody
someone
sopho
submit
support
syma
tanford.e
the.bat
unix
unix
usenet
utgers.ed
webmaster
you
your