W32/Mytob-KH

Please follow the instructions for removing worms.

W32/Mytob-KH is a mass-mailing worm and IRC backdoor Trojan for the Windows platform.

W32/Mytob-KH 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.

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

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
WINDOWS SYSTEM
efefefe.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
WINDOWS SYSTEM
efefefe.exe

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

HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess
Start
4

Note: disabling autostart for the SharedAccess service deactivates the Microsoft Internet Connection Firewall (ICF).

W32/Mytob-KH also includes functionality to silently download, install and run new software.

W32/Mytob-KH modifies the HOSTS file by appending the following lines, preventing access to the sites specified:

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

W32/Mytob-KH is capable of spreading through email. Email sent by W32/Mytob-KH has the following properties:

Subject line chosen from:

  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
  Your password has been updated
  Your password has been successfully updated
  You have successfully updated your password
  Your new account password is approved

Message text chosen from:

  Dear <company name> Member,

  We have temporarily suspended your email account <Email address>.

  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 <company name> account.

  Sincerely,The <company name> Support Team

  +++ Attachment: No Virus (Clean)
  +++ <company name> Antivirus - <web address>



  Dear <company name> 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 <company name> Support Team

  +++ Attachment: No Virus found
  +++ <company name> Antivirus - <web address>



  Dear user <username>,

  You have successfully updated the password of your <company name> account.

  If you did not authorize this change or if you need assistance with your account, please contact <company name> customer service at: <email address>

  Thank you for using <company name>!The <company name> Support Team

  +++ Attachment: No Virus (Clean)
  +++ <company name> Antivirus - <web address>



  Dear user <username>,

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 User Profile ( x ) records are out of date.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

  Thank you for using <company name>!
  The <company name> Support Team

  +++ Attachment: No Virus (Clean)
  +++ <company name> Antivirus - <web address>

The attached file consists of any of the following base names followed by the extension ZIP:

  important-details
  account-details
  email-details
  account-info
  document
  readme
  account-report
  updated-password
  email-password
  new-password
  password
  approved-password
  account-password
  accepted-password
  <random characters>

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-KH harvests email addresses from files on the infected computer and from the Windows address book.