W32/Mytob-CR

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-CR is a mass-mailing worm and IRC backdoor Trojan.

W32/Mytob-CR runs continuously in the background, providing a backdoor server which allows a remote intruder to gain access and control over the computer via IRC channels, including the ability to download and execute files on the infected computer.

W32/Mytob-CR can spread by sending itself as an email attachment to email addresses it harvests from the infected computer, either as an attachment with a double-extension or as a zip file containing a file with a double-extension. W32/Mytob-CR avoids sending emails to addresses containing certain strings in them.

W32/Mytob-CR processes the emails it has harvested by splitting them into name and domain. Once it has sent itself to the emails it has harvested, it uses a predefined list of names with the harvested domains. W32/Mytob-CR spoofs the sender, sending emails as if from one of the following at the same domain as the recipient:

support
administrator
mail
service
admin
info
register
webmaster

For example if sending itself to name@example.com, W32/Mytob-CR might send the email as if from admin@example.com.

Emails sent by the worm have characteristics from the following:

Subject line:

Your password has been updated
Your password has been successfully updated
You have successfully updated your password
Your new account password is approved
Your Account is Suspended
*DETECTED* Online User Violation
Your Account is Suspended For Security Reasons
Warning Message: Your services near to be closed.
Important Notification
Members Support
Security measures
Email Account Suspension
Notice of account limitation
<random characters>

Message text - a formatted version of one of the following:

Dear user <recipient's username>,

You have successfully updated the password of your <recipient's domain> account.

If you did not authorize this change or if you need assistance with your account, please contact <recipient's domain> customer service at: <spoofed sender address>

Thank you for using <recipient's domain>!
The <recipient's domain> Support Team <BR>

+++ Attachment: No Virus (Clean)
+++ <recipient's domain> Antivirus - www.<recipient's domain>

Dear user <recipient's username>,

It has come to our attention that your <recipient's domain> User Profile ( x ) records are out of date. For further details see the attached document.

Thank you for using <recipient's domain>!
The <recipient's domain> Support Team

+++ Attachment: No Virus (Clean)
+++ <recipient's domain> Antivirus - www.<recipient's domain>

Dear <recipient's username> Member,

We have temporarily suspended your email account <recipient's domain>.

This might be due to either of the following reasons:

1. A recent change in your personal information (i.e. change of address).
2. Submiting invalid information during the initial sign up process.
3. An innability to accurately verify your selected option of subscription due to an internal error within our processors.
See the details to reactivate your <recipient's domain> account.

Sincerely,The <recipient's domain> Support Team

+++ Attachment: No Virus (Clean)
+++ <recipient's domain> Antivirus - www.<recipient's domain>

Dear <recipient's domain> Member,

Your e-mail account was used to send a huge amount of unsolicited spam messages during the recent week. If you could please take 5-10 minutes out of your online experience and confirm the attached document so you will not run into any future problems with the online service.

If you choose to ignore our request, you leave us no choice but to cancel your membership.

Virtually yours,
The <recipient's domain> Support Team

+++ Attachment: No Virus found
+++ <recipient's domain> Antivirus - www.<recipent's domain>

Attachment name:

updated-password
email-password
new-password
password
approved-password
account-password
accepted-password
important-details
account-details
email-details
account-info
document
readme
account-report

First extension (of attachment or of file inside zip):

doc
htm
txt

Second extension (of attachment or of file inside zip):

pif
scr
exe
cmd
bat

If the attachment is a zip file it will have the same base name as the double-extension file inside.

Example attachment names include document.txt.pif and information.doc.cmd, usually with a large number of spaces between the extensions.

W32/Mytob-CR copies itself to the Window system folder with the filename deneme.exe and sets the following registry entries to run itself on system startup:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\
WINDOWS DENEME =
deneme.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices\
WINDOWS DENEME =
deneme.exe

W32/Mytob-CR sets the following registry entries, disabling the automatic startup of other software:

HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess
Start
4

W32/Mytob-CR attempts to terminate a large number of processes related to security and anti-virus programs including REGEDIT.EXE, MSCONFIG.EXE and NETSTAT.EXE.

W32/Mytob-CR attempts to download a file from http://www.gameniac.com to C:\winsock.exe. This file is currently detected as Troj/Ranck-CR.

W32/Mytob-CR modifies the Windows hosts file in order to block access to the following 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 kaspersky-labs.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 pandasoftware.com
127.0.0.1 www.pandasoftware.com
127.0.0.1 www.trendmicro.com
127.0.0.1 www.grisoft.com
127.0.0.1 www.microsoft.com
127.0.0.1 microsoft.com
127.0.0.1 www.virustotal.com
127.0.0.1 virustotal.com
127.0.0.1 www.amazon.com
127.0.0.1 www.amazon.co.uk
127.0.0.1 www.amazon.ca
127.0.0.1 www.amazon.fr
127.0.0.1 www.paypal.com
127.0.0.1 paypal.com
127.0.0.1 moneybookers.com
127.0.0.1 www.moneybookers.com
127.0.0.1 www.ebay.com
127.0.0.1 ebay.com

Sophos's anti-virus products include Genotype ™ detection technology, which can proactively protect against new threats without requiring an update. Sophos customers have been protected against W32/Mytob-CR (detected as W32/Mydoom-Gen) since version 3.94.