W32/Mytob.KR is an email worm. This worm is a variant of W32/Mytob. The worm will infect Windows systems and spreads through email.

The subject of the infected mail will be any one of the following;

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

The body of the infected mail will be any one of the following;

Dear user [Random name],

It has come to our attention that your [Random name] User Profile ( x ) records are out of date.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

Thank you for using [Random name]!
The [Random] Support Team

+++ Attachment: No Virus (Clean)
+++ [Random] Antivirus - www.[Random]

Dear user [Random name],

You have successfully updated the password of your [Random name] account.

If you did not authorize this change or if you need assistance with your account, please contact [Random] customer service at: [Random]

Thank you for using [Random name]!
The [Random name] Support Team

+++ Attachment: No Virus (Clean)
+++ [Random] Antivirus - www.[Random]

Dear [Random name] Member,

We have temporarily suspended your email account [Random name].

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 [Random] account.

Sincerely,The [Random name] Support Team

+++ Attachment: No Virus (Clean)
+++ [Random] Antivirus - www.[Random]

Dear [Random 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 [Random name] Support Team

+++ Attachment: No Virus found
+++ [Random] Antivirus - www.[Random]

The infected attachment will be any one of the following;

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

The extension of the infected attachment will be any one of the following;

zip, bat, cmd, exe, scr or pif

Upon execution of the infected attachment, the worm copies itself as scrigz.exe in the Windows System folder.

The worm modifies registry at the following location to load itself during each startup.

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

To propagate itself, the worm scans the files having the following extensions and collects all the available email addresses from the infected system.

adb, asp, dbx, htm, php, pl, sht, tbb and wab.

It can also generate email address by adding the following name to the domain name gathered from previously collected email addresses.

steve , brent, brian , claudia, david , debby, frank , george, helen , brenda, james , jerry, jimmy , julie, kevin , linda, maria , michael, peter , robert, sales , sandra, smith and andrew.

The worm mails itself to these addresses using its own SMTP engine.

It also tries to terminate some of the security related processes and prevents access to some of the security related websites.

This worm first appeared on September 28, 2005.

 Other names of W32/Mytob.KR Worm:

This Worm is also known as WORM_MYTOB.KR.