WORM_MYTOB.NB

Malware type: Worm

Aliases: Net-Worm.Win32.Mytob.cu (Kaspersky), W32.Mytob@mm (Symantec), Worm/Mytob.LZ (Avira), W32/Mytob-FZ (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Infection Channel 1 : Propagates via email


Infection Channel 2 : Propagates via network shares


Infection Channel 3 : Propagates via software vulnerabilities


Description: 

Similar to other 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. Using its own SMTP mail engine makes it easier for this worm to send out email messages, while maintaining transparency on the affected system.

The email it sends has the following details:

Subject: (any of the following)

• Notice of account limitation
• YOU ARE BANNED!!!
• WE HAVE SUSPENDED YOUR ACCOUNT
• *DETECTED* ONLINE USER VIOLATION
• SECURITY MEASURES
• WARNING MESSAGE: YOUR SERVICES NEAR TO BE CLOSED.
• MEMBERS SUPPORT
• HASH
• YOUR ACCOUNT IS SUSPENDED FOR SECURITY REASONS
• We have suspended your account
• You are banned!!!
• Your Account is Suspended For Security Reasons
• Warning Message: Your services near to be closed.
• Members Support
• Email Account Suspension
• Your Account is Suspended
• *WARNING* Your email account is suspended
• *DETECTED* Online User Violation
• Important Notification
• IMPORTANT NOTIFICATION

Message body: (any of the following)

Dear {name of recipient} Member,

We have temporarily suspended your email account {email account of user}.
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 {email account of user} account.

Sincerely,
The {random name} Support Team

Attachment: No Virus (Clean)
{random domain name} Antivirus www.{random antivirus Web site}.com

---
Dear {name of recipient} 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

Attachment: (any of the following file names)
{random}

• account-info
• account-details
• readme
• document
• account-report
• important-details
• email-details
• information

(with any of the following first extension names)

• DOC
• HTM
• TMP
• TXT

Note: The file name extension of the archived file is followed by empty spaces, a dot, and any of the following extensions:

• BAT
• CMD
• EXE
• PIF
• SCR
• ZIP

This worm also propagates by dropping a copy of itself in accessible network shares. It accesses an affected system by logging on using the account of the currently logged-on user.

Furthermore, it also propagates across networks by taking advantage of the Windows LSASS vulnerability, which allows remote code execution. The said vulnerability is discussed in detail in the Microsoft Security Bulletin MS04-011 page.

This worm has backdoor capabilities. It opens a random port, 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.

For additional information about this threat, see:

Description created: Nov. 28, 2005 9:58:22 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 94,689 Bytes (compressed)

Ports used: Random

Initial samples received on: Nov 28, 2005

Compression type: MEW

Vulnerability used:  (MS04-011) Security Update for Microsoft Windows (835732)

Payload 1: Compromises system security

Details:

Installation and Autostart Technique

This memory-resident worm arrives as an email attachment. Upon execution, it drops a copy of itself as MSCONFGH.EXE in the Windows system folder. It then creates the following registry entry in an attempt to ensure its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Win32 Cnfg32 = "msconfgh.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
Win32 Cnfg32 = "msconfgh.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices
Win32 Cnfg32 = "msconfgh.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Win32 Cnfg32 = "msconfgh.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
Win32 Cnfg32 = "msconfgh.exe"

Network Propagation and Exploits

This memory-resident worm propagates by dropping a copy of itself in accessible network shares. It accesses an affected system by logging on using the account of the currently logged-on user.

It also takes advantage of the Windows LSASS vulnerability to propagate across networks. The said vulnerability, which allows remote code exection, is discussed in detail in the Microsoft Security Bulletin MS04-011 page.

Propagation via Email

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

The email it sends has the following details:

Subject: (any of the following)

• Notice of account limitation
• YOU ARE BANNED!!!
• WE HAVE SUSPENDED YOUR ACCOUNT
• *DETECTED* ONLINE USER VIOLATION
• SECURITY MEASURES
• WARNING MESSAGE: YOUR SERVICES NEAR TO BE CLOSED.
• MEMBERS SUPPORT
• HASH
• YOUR ACCOUNT IS SUSPENDED FOR SECURITY REASONS
• We have suspended your account
• You are banned!!!
• Your Account is Suspended For Security Reasons
• Warning Message: Your services near to be closed.
• Members Support
• Email Account Suspension
• Your Account is Suspended
• *WARNING* Your email account is suspended
• *DETECTED* Online User Violation
• Important Notification
• IMPORTANT NOTIFICATION

Message body: (any of the following)

Dear {name of recipient} Member,

We have temporarily suspended your email account {email account of user}.
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 {email account of user} account.

Sincerely,
The {random name} Support Team

Attachment: No Virus (Clean)
{random domain name} Antivirus www.{random antivirus Web site}.com

---
Dear {name of recipient} 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

Attachment: (any of the following file names)
{random}

• account-info
• account-details
• readme
• document
• account-report
• important-details
• email-details
• information

(with any of the following first extension names)

• DOC
• HTM
• TMP
• TXT

Note: The file name extension of the archived file is followed by empty spaces, a dot, and any of the following extensions:

• BAT
• CMD
• EXE
• PIF
• SCR
• ZIP

It may also generate email addresses by combining the following names appended with a domain name, which it copies from previously harvested email addresses, and from the Windows Address Book:

  • adam
  • alex
  • andrew
  • anna
  • bill
  • bob
  • brenda
  • brent
  • brian
  • claudia
  • dan
  • dave
  • david
  • debby
  • frank
  • fred
  • george
  • helen
  • jack
  • james
  • jane
  • jerry
  • jim
  • jimmy
  • joe
  • john
  • jose
  • josh
  • julie
  • kevin
  • leo
  • linda
  • maria
  • mary
  • matt
  • michael
  • mike
  • paul
  • peter
  • ray
  • robert
  • sales
  • sam
  • sandra
  • serg
  • smith
  • stan
  • steve
  • ted
  • tom

It also harvests email addresses from the folder, Local Settings\Temporary Internet Files and in all its subfolders, as well as from files with the following extension names:

  • ADB
  • ASP
  • CGI
  • DBX
  • HTM
  • HTML
  • JSP
  • PHP
  • SHT
  • TBB
  • TXT
  • WAB
  • XML

This worm spoofs the From field by using any of the following strings along with the email addresses it gathers or generates:

  • gate
  • mail
  • mail1
  • mx
  • mx1
  • mxs
  • ns
  • relay
  • smtp

Moreover, it avoids sending email messages to email addresses containing any of the following substrings:

  • abuse
  • accoun
  • admin
  • administrator
  • andrew
  • anyone
  • brenda
  • brent
  • brian
  • certific
  • claudia
  • contact
  • david
  • debby
  • feste
  • frank
  • george
  • gold-certs
  • google
  • helen
  • icrosoft
  • james
  • jerry
  • jimmy
  • julie
  • kevin
  • linda
  • linux
  • listserv
  • maria
  • michael
  • nobody
  • noone
  • nothing
  • ntivi
  • peter
  • postmaster
  • privacy
  • rating
  • register
  • robert
  • sales
  • samples
  • sandra
  • secur
  • service
  • smith
  • somebody
  • someone
  • steve
  • submit
  • support
  • the.bat
  • webmaster

It avoids email addresses with domain names containing any of the following substrings:

  • acketst
  • arin.
  • be_loyal:
  • berkeley
  • borlan
  • example
  • google
  • hotmail
  • ibm.com
  • icrosof
  • inpris
  • isc.o
  • isi.e
  • kernel
  • linux
  • mit.e
  • mozilla
  • mydomai
  • nodomai
  • panda
  • rfc-ed
  • ripe.
  • ruslis
  • secur
  • sendmail
  • sopho
  • tanford.e
  • usenet
  • utgers.ed

This worm queries the following registry key for available SMTP servers:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Account Manager\Accounts

Backdoor Capabilities

This worm also has backdoor capabilities. It opens a random port, and then connects to the Internet Relay Chat (IRC) server. It then joins the ##tob IRC channel where it receives the following commands from a remote malicious user:

  • Download files
  • Execute files
  • Perform other IRC commands
  • Restart system
  • Set up FTP server using random port

Platforms Affected

This worm runs on Windows 2000, XP, and Server 2003.

Analysis By: Millette Regulacio


SOLUTION


Minimum scan engine version needed: 7.000

Pattern file needed: 2.972.07

Pattern release date: Nov 28, 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:

Identifying the Malware Program

To remove this malware, first identify the malware program.

  1. Scan your system with your Trend Micro antivirus product.
  2. NOTE the path and file name of all files detected as WORM_MYTOB.NB.

Trend Micro customers need to download the latest virus pattern file before scanning their system. Other users can use Housecall, the Trend Micro online virus scanner.

Terminating the Malware Program

This procedure terminates the running malware process. You will need the name(s) of the file(s) detected earlier.

If the process you are looking for is not in the list displayed by Task Manager, proceed to the succeeding solution set.

  1. Open Windows Task Manager.
    • On Windows 2000, XP, and Server 2003, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. Close Task Manager.

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 2000
  2. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and Server 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_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    Win32 Cnfg32 = "msconfgh.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows>CurrentVersion>RunOnce
  5. In the right panel, locate and delete the entry:
    Win32 Cnfg32 = "msconfgh.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:
    Win32 Cnfg32 = "msconfgh.exe"
  8. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  9. In the right panel, locate and delete the entry:
    Win32 Cnfg32 = "msconfgh.exe"
  10. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>RunOnce
  11. In the right panel, locate and delete the entry:
    Win32 Cnfg32 = "msconfgh.exe"
  12. Close Registry Editor.

Important Windows XP Cleaning Instructions

Users running Windows 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

If you are currently running in safe mode, please restart your system normally before performing the following solution.

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

Applying Patches

This malware exploits known vulnerabilities in Windows. Download and install the fix patch supplied by Microsoft. Refrain from using this product until the appropriate patch has been installed. Trend Micro advises users to download critical patches upon release by vendors.




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