W32/Mytob-CZ

Please follow the instructions for removing worms.

Replace the Hosts file from a backup or edit it in Notepad to remove the changes that the worm has made.

You will also need to edit the following registry entries, if they are present. Please read the warning about editing the registry.

At the taskbar, click Start|Run. Type 'Regedit' and press Return. The registry editor opens.

Before you edit the registry, you should make a backup. On the 'Registry' menu, click 'Export Registry File'. In the 'Export range' panel, click 'All', then save your registry as Backup.

Locate the HKEY_LOCAL_MACHINE entries:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices

and remove any reference to any file you deleted.

Close the registry editor.

W32/Mytob-CZ is a mass-mailing worm and backdoor Trojan that can be controlled through the Internet Relay Chat (IRC) network.

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

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
http://www.lienvandekelder.be
"Lien.exe"

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices
http://www.lienvandekelder.be
"Lien.exe"

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

Subject line:

*DETECTED* Online User Violation

*WARNING* Your Email Account Will Be Closed

Account Alert

Email Account Suspension

Important Notification

Notice of account limitation

Notice: **Last Warning**

Security measures

Your Email Account is Suspended For Security Reasons

Message text:

Once you have completed the form in the attached file , your account records will not be interrupted and will continue as normal.

The original message has been included as an attachment.

We regret to inform you that your account has been suspended due to the violation of our site policy, more info is attached.

We attached some important information regarding your account.

Please read the attached document and follow it's instructions.

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. The base filenames are randomly chosen from:

account-details
document
email-doc
email-info
info-text
information
information
instructions

W32/Mytob-CZ harvests email addresses from files on the infected computer and from the Windows address book. The worm avoids sending email to addresses 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