BAT.Mumu.B.Worm

SUMMARY

BAT.Mumu.B.Worm is a collection of batch files and utilities, as well as a hacktool named Hacktool.Hacline. The names and functions of the files may change. The information discussed in this writeup is based on the samples that Security Response have reviewed.

This worm will spread using administrative shares on Windows NT, 2000, and XP systems. Although the worm can execute on Windows 95/98/Me systems, it does not harm these systems.

Protection

• Virus Definitions (LiveUpdate™ Weekly) November 12, 2003
• Virus Definitions (Intelligent Updater) November 7, 2003

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Compromises Security Settings: Gives a hacker full remote access to host.

Distribution

• Distribution Level: Low
• Target of Infection: Computers on the local area network with weak passwords.

TECHNICAL DETAILS

BAT.Mumu.B.Worm is a large collection of files that use each other to spread over administrative shares on Windows NT, 2000, and XP systems. The files associated with this worm are:

• 10.bat: A malicious batch file.
• AN.bat: A malicious batch file.
• hack.bat: A malicious batch file.
• simple.exe: A Hacktool that will be detected as Hacktool.Hacline.
• ipc.bat: A malicious batch file.
• muma.bat: A malicious batch file.
• near.bat: A malicious batch file.
• gogo.vbe: A malicious VBScript.
• ts.exe: A UPX-packed executable that will run a terminal service on the host.
• ipcpass.txt: A text file.
• ioginer.txt: A text file.
• reg.reg: A registry script that adds keys, so that ss.bat is executed on startup.
• rep.exe: A legitimate utility for replacing strings.
• psexec.exe: A legitimate utility from Sysinternals to remotely start the processes.
• random.bat: A malicious batch file.
• replace.bat: A malicious batch file.
• ss.bat: A batch file that will create an admin user, as well as run the psexec on the remote machine.
• start.bat: A malicious batch file.
• sc.exe: A legitimate utility for service control.
• test.bat: A malicious batch file.

When this worm is executed, it executes the AN.bat file, which calls several other files that perform the following actions:

1. Stops and deletes services named "Query Service" or "Application."
   
   
2. Adds itself as the service "Query Service."
   
   
3. Adds an Administrator-level user, "admin," with the password, "!@#123QWEqwe."
   
   
4. Installs "Windows Terminal Service" on port 3306.
   
   
5. Deletes the logines.txt file and calls the hacktool "Simple.exe," which Symantec antivirus products detect as Hacktool.Hacline.
   
   The command line parameter passed to the Simple.exe file will be a range of IP addresses. The range will start with the first two octets of the IP address (which have been randomized) with .0.1 added, and the end with the same first two octets of the IP address, but with .255.255 added.
   
   Hfind.exe will attempt to find the password for the administrative shares and save this information in a file named logines.txt.
   
   The tool will use the following passwords:
   
   password
   passwd
   admin
   pass
   123
   1234
   12345
   123456
   <blank>
   
   
6. Replaces the iogner.txt file with logines.txt.
   
   
7. For any account that Simple.exe has discovered, the worm attempts to copy all the aforementioned files to the %System% folder using the administrative shares.
   
   

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   Note: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
   

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8. If the files were successfully copied, the worm will attempt to launch Start.bat using the tool Psexec.exe. This will effectively start the worm on the remote computer.
   
   
9. Runs the Netstat command on the system.
   
   
10. Attempts to call the batch file, Near.bat, supplying it with IP addresses.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Disable System Restore (Windows Me/XP).
2. Find and stop the process (Windows NT/2000/XP).
3. Find and stop the service (Windows NT/2000/XP).
4. Revert the modifications made to the admin account (Windows NT/2000/XP).
5. Update the virus definitions.
6. Run a full system scan and delete all the files detected as BAT.Mumu.B.Worm or Hacktool.Hacline. Delete any additional undetected and unwanted files mentioned above.

For specific details on each of these steps, read the following instructions.

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

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Note: When you are completely finished with the removal procedure, and you are satisfied that the threat has been removed, you should reenable System Restore by following the instructions in the aforementioned documents.

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For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.


2. Finding and stopping the process (Windows NT/2000/XP)

1. Press Ctrl+Alt+Delete once.
2. Click Task Manager.
3. Click the Processes tab.
4. Double-click the Image Name column header to alphabetically sort the processes.
5. Scroll through the list and look for Ts.exe.
6. If you find the file, click it, and then click End Process.
7. Exit the Task Manager.

3. Finding and stopping the service (Windows NT/2000/XP)

1. Click Start, and then click Run.
2. Type services.msc, and then click OK.
3. Locate and select the service, "Query Service."
4. Click Action, and then click Properties.
5. Click Stop.
6. Change Startup Type to Manual.
7. Click OK and close the Services window.
8. Restart the computer.

4. Reverting the modifications made to the admin account (Windows NT/2000/XP)
If you are not sure how to do this, or what to reset the account to (if the account is needed on your system) contact your network administrator.

5. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
• Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

6. Scanning for and deleting the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with BAT.Mumu.B.Worm or Hacktool.Hacline, click Delete.
4. Optional: Refer to the list in the "Technical Details" section and use Windows Explorer to delete any of the non-malicious files that you find.