WORM_MYTOB.HS

Malware type: Worm

Aliases: Net-Worm.Win32.Mytob.bt (Kaspersky), W32.Mytob.HG@mm (Symantec), Worm/Mytob.IL (Avira), W32/Mytob-DI (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, 2000, ME, NT, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Description: 

Similar to other WORM_MYTOB variants, this memory-resident worm propagates by sending a copy of itself as an attachment to an email message, which it sends to target recipients using its own Simple Mail Transfer Protocol (SMTP) engine.

The email it sends out has the following details:

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

Message body:
This is a multi-part message in MIME format.

Attachment: (any of the following file names)
accepted-password
account-details
account-info
account-password
account-report
approved-password
document
email-details
email-password
important-details
new-password
password
readme
updated-password

(with any of the following as 1st extension)
DOC
HTM
TXT

(with any of the following as 2nd extension)
EXE
PIF
SCR

This worm sends copies of itself to target email addresses it has gathered from the Windows Address Book (WAB). It may also generate email addresses by using a list of names and any of the domain names of the previously gathered addresses.

This worm has backdoor capabilities. It opens varied ports, which allows a remote user to perform malicious commands on the affected machine. The said routine provides remote users virtual control over affected systems, thus compromising system security.

It also prevents users from acessing several several Web sites by modifying the HOSTS file.

For additional information about this threat, see:

Description created: Jul. 8, 2005 8:03:11 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 32,804 Bytes

Initial samples received on: Jul 8, 2005

Compression type: Upack

Payload 1: Compromises system security

Trigger condition 1: Upon execution

Payload 2: Redirects users to local machine

Trigger condition 1: When the user accesses certain Web sites

Details:

Installation and Autostart Technique

This memory-resident worm arrives on a system as a zipped email attachment. Upon execution, it drops a copy of itself in the Windows system folder as the file M0USE.EXE.

It then creates the following registry entries to ensure its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\RunServices
USERINTERFACE REPORT3R = "M0USE.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
USERINTERFACE REPORT3R = "M0USE.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
USERINTERFACE REPORT3R = "M0USE.exe"

In addition, it modifies the following registry entry:


From:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe"


To:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe M0USE.exe"

It also sets the following registry entry to disable Windows XP SP2 Firewall at startup:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SharedAccess
Start = "4"

Propagation via Email

This worm propagates by sending a copy of itself as an attachment to email messages, which it then sends to target recipients using its own Simple Mail Transfer Protocol (SMTP) engine.

The email it sends out has the following details:

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

Message body:
This is a multi-part message in MIME format.

Attachment: (any of the following file names)
� {Random}
� accepted-password
� account-details
� account-info
� account-password
� account-report
� approved-password
� document
� email-details
� email-password
� important-details
� new-password
� password
� readme
� updated-password

(with any of the following as 1st extension)
� DOC
� HTM
� TXT

(with any of the following as 2nd extension)
� EXE
� PIF
� SCR

It gathers target email addresses from the Windows Address Book (WAB). It may also generate email addresses by using any of the following names appended with a domain name, which it copies from the previously harvested email addresses:

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

It avoids sending email messages to addresses that contain any of the following substrings:

  • -._!@
  • abuse
  • accoun
  • acketst
  • admin
  • anyone
  • arin.
  • be_loyal:
  • berkeley
  • borlan
  • certific
  • contact
  • example
  • feste
  • gold-certs
  • google
  • hotmail
  • ibm.com
  • icrosof
  • icrosoft
  • inpris
  • isc.o
  • isi.e
  • kernel
  • linux
  • listserv
  • mit.e
  • mozilla
  • mydomai
  • nobody
  • nodomai
  • noone
  • nothing
  • ntivi
  • panda
  • postmaster
  • privacy
  • rating
  • rfc-ed
  • ripe.
  • ruslis
  • samples
  • secur
  • sendmail
  • service
  • somebody
  • someone
  • sopho
  • submit
  • support
  • tanford.e
  • the.bat
  • usenet
  • utgers.ed
  • webmaster

Backdoor Capabilities

This worm has backdoor capabilities. It opens varied ports, which enables it to connect to the Internet Relay Chat (IRC) server name.turkintikamtugayi.com, where it listens for commands coming from a remote malicious user. Some of these commands are as follows:

  • Download files
  • List running processes
  • Remove or update a copy of itself
  • Start or terminate its mass-mailing routine

HOSTS File Modification

This worm also modifies the system's HOSTS file, which contains host name to IP address mappings. It is usually located in the following folders:

    %System%\drivers\etc

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 95, 98, and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP.)

The said routine is done so that the following sites can no longer be accessed by affected users:

  • avp.com
  • ca.com
  • customer.symantec.com
  • dispatch.mcafee.com
  • download.mcafee.com
  • ebay.com
  • f-secure.com
  • kaspersky-labs.com
  • kaspersky.com
  • liveupdate.symantec.com
  • liveupdate.symantecliveupdate.com
  • mast.mcafee.com
  • mcafee.com
  • microsoft.com
  • moneybookers.com
  • my-etrust.com
  • nai.com
  • networkassociates.com
  • pandasoftware.com
  • paypal.com
  • rads.mcafee.com
  • secure.nai.com
  • securityresponse.symantec.com
  • sophos.com
  • symantec.com
  • trendmicro.com
  • update.symantec.com
  • updates.symantec.com
  • us.mcafee.com
  • viruslist.com
  • virustotal.com
  • www.amazon.ca
  • www.amazon.co.uk
  • www.amazon.com
  • www.amazon.fr
  • www.avp.com
  • www.ca.com
  • www.ebay.com
  • www.f-secure.com
  • www.grisoft.com
  • www.kaspersky.com
  • www.mcafee.com
  • www.microsoft.com
  • www.moneybookers.com
  • www.my-etrust.com
  • www.nai.com
  • www.networkassociates.com
  • www.pandasoftware.com
  • www.paypal.com
  • www.sophos.com
  • www.symantec.com
  • www.trendmicro.com
  • www.viruslist.com
  • www.virustotal.com

Other Details

This worm runs on Windows 95, 98, 2000, ME, NT, XP, and Server 2003. It is compiled using Microsoft Visual C%20%20, a high level programming language. Unlike other variants, this worm does not check for running processes of itself in memory, thus multiple instances of itself can occur on the system.

Analysis By: Roddell Aquino Santos

Revision History:

 

October 7, 2005 - Insertion of Automatic Removal Instructions

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.720.08

Pattern release date: Jul 9, 2005


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

AUTOMATIC REMOVAL INSTRUCTIONS

MANUAL REMOVAL INSTRUCTIONS

Terminating the Malware Program

This procedure terminates the running malware process.

  1. Open Windows Task Manager.
    � On Windows 95, 98, and ME, press
    CTRL%20ALT%20DELETE
    � On Windows NT, 2000, XP and Server 2003, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the process:
    M0USE.exe
  3. Select the malware process, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. To check if the malware process has been terminated, close Task Manager, and then open it again.
  5. Close Task Manager.

*NOTE: On systems running Windows 95, 98, and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions. If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Editing the Registry

This malware modifies the system's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. HOW TO: Backup, Edit, and Restore the Registry in Windows 95, Windows 98, and Windows ME
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and 2003

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing at startup.

If the registry entries below are not found, the malware may not have executed as of detection. If so, proceed to the succeeding solution set.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    USERINTERFACE REPORT3R = "M0USE.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>Run
  5. In the right panel, locate and delete the entry:
    USERINTERFACE REPORT3R = "M0USE.exe"
  6. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>RunServices
  7. In the right panel, locate and delete the entry:
    USERINTERFACE REPORT3R = "M0USE.exe"
  8. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows NT>CurrentVersion>Winlogon
  9. In the right panel, locate the entry:
    Shell=Explorer.exe M0USE.exe"
  10. Right-click on this registry entry and choose Modify.
    Change the value of this entry to:
    Shell = "Explorer.exe"
  11. Close Registry Editor.

Restoring Modified Registry Entries

To restore this entry to its default value, please perform the following instructions:

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>System>CurrentControlSet>
    Services>SharedAccess
  3. In the right panel, reset the following value:
    From: Start = "4"

  4. To: Start = "3"
  5. Close Registry Editor.

Removing Malware Entries from the HOSTS File

Deleting malware entries from the HOSTS file removes all malware-made changes on host name association.

  1. Open the following file using a text editor (such as NOTEPAD):
    %System%\drivers\etc\HOSTS
    (Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 95, 98, and ME, C:\WINNT\System32 on Windows NT and 2000, and C:\Windows\System32 on Windows XP and Server 2003.)
  2. Delete the following entries:
      � 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
  3. Save the file and close the text editor.

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected systems.

Users running other Windows versions can proceed with the succeeding procedure set(s).

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and delete files detected as WORM_MYTOB.HS. To do this, Trend Micro customers must download the latest virus pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro's online virus scanner.




Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.