W32/Mytob-FZ

Please follow the instructions for removing worms.

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\RunOnce\
HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices\

and remove any reference to any file you deleted.

Each user has a registry area named HKEY_USERS\[code number indicating user]\. For each user locate the entries:

HKU\[code number]\Software\Microsoft\Windows\
CurrentVersion\Run\

HKU\[code number]\Software\Microsoft\Windows\
CurrentVersion\RunOnce\

and remove any reference to any file you deleted.

Close the registry editor.

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

W32/Mytob-FZ 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.

W32/Mytob-FZ spreads to other network computers by exploiting common buffer overflow vulnerabilities, including: LSASS (MS04-011) and ASN.1 (MS04-007).

W32/Mytob-FZ 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.

Emails sent by W32/Mytob-FZ sends emails in the following format, with details filled in to make the email look more authentic:

Subject line chosen from:

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 chosen from (the worm will insert the username and the email domain of the addressee into the email):

'Dear user <UserName>,

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

If you did not authorize this change or if you need assistance with your account, please contact <domain> customer service at: <sender@domain>
Thank you for using <domain>!
The <domain> Support Team

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

'Dear user <UserName>,

It has come to our attention that your <domain> User Profile ( x ) records are out of date. For further details see the attached document.
Thank you for using <domain>!
The <domain> Support Team

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

'Dear <domain> Member,

We have temporarily suspended your email account <UserEmailAddress>.

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 <domain> account.

Sincerely,The <domain> Support Team

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

'Dear <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 <domain> Support Team

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

The attached file consists of a base name followed by the extension ZIP. The worm may optionally create double extensions where the first extension is DOC, TXT or HTM and the final extension is BAT, CMD, PIF, SCR, EXE or ZIP. The base filenames are randomly chosen from:

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
<random characters>

The zip file will contain the worm with double extension. The first extension will be one of DOC, HTM, TXT followed by spaces and the second extension is EXE, SCR or PIF.

W32/Mytob-FZ harvests email addresses from files on the infected computer and from the Windows address book.

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-FZ (detected as W32/Forbot-Fam) since version 3.98. W32/Mytob-FZ is a mass-mailing worm and backdoor Trojan that can be controlled through the Internet Relay Chat (IRC) network.

W32/Mytob-FZ 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.

W32/Mytob-FZ spreads to other network computers by exploiting common buffer overflow vulnerabilities, including: LSASS (MS04-011) and ASN.1 (MS04-007).

W32/Mytob-FZ 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-FZ copies itself to <System>\msconfgh.exe.

The following registry entries are created to run msconfgh.exe on startup:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Win32 Cnfg32
msconfgh.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Win32 Cnfg32
msconfgh.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce
Win32 Cnfg32
msconfgh.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
Win32 Cnfg32
msconfgh.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
Win32 Cnfg32
msconfgh.exe

The file msconfgh.exe is registered as a new file system driver service named "Win32 Cnfg32", with a display name of "Win32 Cnfg32". Registry entries are created under:

HKLM\SYSTEM\CurrentControlSet\Services\Win32 Cnfg32\

Emails sent by W32/Mytob-FZ sends emails in the following format, with details filled in to make the email look more authentic:

Subject line chosen from:

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 chosen from (the worm will insert the username and the email domain of the addressee into the email):

'Dear user <UserName>,

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

If you did not authorize this change or if you need assistance with your account, please contact <domain> customer service at: <sender@domain>
Thank you for using <domain>!
The <domain> Support Team

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

'Dear user <UserName>,

It has come to our attention that your <domain> User Profile ( x ) records are out of date. For further details see the attached document.
Thank you for using <domain>!
The <domain> Support Team

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

'Dear <domain> Member,

We have temporarily suspended your email account <UserEmailAddress>.

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 <domain> account.

Sincerely,The <domain> Support Team

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

'Dear <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 <domain> Support Team

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

The attached file consists of a base name followed by the extension ZIP. The worm may optionally create double extensions where the first extension is DOC, TXT or HTM and the final extension is BAT, CMD, PIF, SCR, EXE or ZIP. The base filenames are randomly chosen from:

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
<random characters>

The zip file will contain the worm with double extension. The first extension will be one of DOC, HTM, TXT followed by spaces and the second extension is EXE, SCR or PIF.

W32/Mytob-FZ harvests email addresses from files on the infected computer and from the Windows address book.

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-FZ (detected as W32/Forbot-Fam) since version 3.98.