W32.Maslan.C@mm

SUMMARY

W32.Maslan.C@mm is a mass-mailing worm that opens a back door and exploits system vulnerabilities on the compromised computer. The worm also steals passwords and uses rootkit techniques.

Protection

• Virus Definitions (LiveUpdate™ Weekly) December 15, 2004
• Virus Definitions (Intelligent Updater) December 9, 2004

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: Medium
• Payload: Allows unauthorized remote access.
• Large Scale E-mailing: Sends a mass-mailing to email addresses gathered from the infected computer.
• Modifies Files: Overwrites certain files.
• Releases Confidential Info: Logs keystrokes.
• Compromises Security Settings: Terminate processes related to security products.

Distribution

• Distribution Level: High
• Subject of Email: 12345
• Name of Attachment: PlayGirls_2.exe
• Size of Attachment: 54,272 bytes
• Ports: TCP port 135

TECHNICAL DETAILS

When W32.Maslan.C@mm runs, it does the following:

1. Creates some of the following files:
   
   • %System%\___j.dll (the part of the worm that is injected into svchost.exe)
   • %System%\___r.exe (the main worm executable)
   • %System%\___synmgr.exe (detected as W32.IRCBot)
   • %System%\___n.exe (detected as W32.IRCBot)
   • %System%\___e (contains a MIME encoded version of the worm)
   • %System%\___u (contains a dropper for the worm)
   • %System%\___prior
   • %System%\___m
   • %System%\___t
   • %Windir%\___n.exe
   • %System%\___AlaScan
     
     Notes:
   • %System% is a variable that refers to the System folder. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
   • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows (Windows 95/98/Me/XP)or C:Winnt (Windows NT/2000).
     
     
2. Injects ___j.dll into the svchost.exe process.
   
   
3. Deletes and recreates the files:
   • %System%Alaftp
   • %System%AlaMail
   • %System%AlaScan
   • %System%AlaDdos
     
     The worm uses these to store data gathered from the infected computer.
     
     
4. Adds the values:
   
   "Microsoft Synchronization Manager" = "___synmgr.exe"
   "Microsoft Windows DHCP" = "___r.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that the worm runs every time Windows starts.
   
   
5. Adds the value:
   
   "Microsoft Synchronization Manager" = "___synmgr.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices
   
   so that the worm runs every time Windows starts.
   
   
6. Starts ___r.exe.
   
   Note: The original file that was executed writes to its own memory space, causing it to crash. The other processes that the worm started continue running.
   
   
7. Terminates the following processes:
   
   • _AVPM.EXE
   • _AVPCC.EXE
   • _AVP32.EXE
   • ZONEALARM.EXE
   • ZAPSETUP3001.EXE
   • ZONALM2601.EXE
   • ZAPRO.EXE
   • VIRUSMDPERSONALFIREWALL.EXE
   • VIR-HELP.EXE
   • VFSETUP.EXE
   • TAUMON.EXE
   • TASKMON.EXE
   • TASKMGR.EXE
   • TASKMG.EXE
   • RESCUE32.EXE
   • PROCESSMONITOR.EXE
   • PADMIN.EXE
   • OUTPOSTINSTALL.EXE
   • OUTPOST.EXE
   • NPROTECT.EXE
   • NORTON_INTERNET_SECU_3.0_407.EXE
   • NETUTILS.EXE
   • NETMON.EXE
   • NC2000.EXE
   • NAVWNT.EXE
   • NAVW32.EXE
   • NAVDX.EXE
   • AUTO-PROTECT.NAV80TRY.EXE
   • NAV.EXE
   • KILLPROCESSSETUP161.EXE
   • KERIO-WRP-421-EN-WIN.EXE
   • KERIO-WRL-421-EN-WIN.EXE
   • KERIO-PF-213-EN-WIN.EXE
   • KAVPF.EXE
   • KAVPERS40ENG.EXE
   • KAVLITE40ENG.EXE
   • JAMMER.EXE
   • GUARDDOG.EXE
   • GUARD.EXE
   • DRWEBUPW.EXE
   • DRWEB32.EXE
   • DRWATSON.EXE
   • CLICK.EXE
   • CLEANPC.EXE
   • CLEANER3.EXE
   • CLEANER.EXE
   • AVPUPD.EXE
   • AVPTC32.EXE
   • AVPM.EXE
   • AVPDOS32.EXE
   • AVPCC.EXE
   • AVP32.EXE
   • AVP.EXE
   • AVKWCTl9.EXE
   • AVKSERVICE.EXE
   • AVKSERV.EXE
   • AVKPOP.EXE
   • AVGUARD.EXE
   • AUTOUPDATE.EXE
   • AUPDATE.EXE
   • ATGUARD.EXE
   • ANTIVIRUS.EXE
   • ANTI-TROJAN.EXE
     
     
8. Uses rootkit techniques to prevent the files and processes whose names start with ___ (three underscore characters) from being visible to users. This may also cause the Task Manager to fail to start.
   
   
9. Scans for computers and tries to exploit the DCOM RPC Vulnerability (described in Microsoft Security Bulletin MS03-026) using TCP port 135.
   
   
10. Opens a back door by connecting to a remote IRC server to receive instructions from a remote attacker.
    
    
11. Monitors Internet Explorer windows that contain one of the following strings:
    
    • evocash
    • e-bullion
    • e-gold
    • mail
    • bank
    • trade
    • paypal
      
      When the worm detects a window containing one of the above strings, it logs keystrokes and sends this information to a remote web site.
      
      
12. Searches the hard drive for the files that contain the following substrings in their paths:
    
    • distr
    • download
    • setup
    • share
      
      
      and have one of the following extensions:
      
    • rar
    • zip
    • pif
    • exe
      
      
      The worm searches for files that meet the above criteria and are greater in size than %System%\___u. The worm then creates a copy of the file in the subfolder \___b, with the same file name and a similar file path.
      
      The worm then overwrites the original file with a copy of %System%\___u. This file will have the same file name, file path, file size, and icon as the original file, but with a .exe extension.
      
      
      Example:
      
      If the worm finds the following file:
      
      C: estshareexample.zip
      
      it overwrites the above file with the following file:
      
      C: estshareexample.exe (a copy of %System%\___u)
      
      and creates the file:
      
      C:\___b estshareexample.zip (a back up of the original file)
      
      
13. May create the folder:
    
    [197 A characters]
    
    that contains the file:
    
    [197 A characters].RAR
    
    
14. Collects email addresses from the files with the following extensions:
    
    • xml
    • xls
    • wsh
    • wab
    • uin
    • txt
    • tbb
    • stm
    • shtm
    • sht
    • php
    • oft
    • ods
    • nch
    • msg
    • mm
    • f
    • mht
    • mdx
    • mbx
    • jsp
    • htm
    • eml
    • dhtm
    • dbx
    • cgi
    • cfg
    • asp
    • adb
      
      Avoids email addresses that contain the following substrings:
      
    • mail.com
    • freemail.com
    • hotmail.com
    • yahoo.com
    • msn.com
    • aol.com
    • subscribe
    • accoun
    • certific
    • listserv
    • ntivi
    • admin
    • mozilla
    • utgers.ed
    • tanford.e
    • pgp
    • acketst
    • secur
    • isc.o
    • isi.e
    • ripe.
    • arin.
    • sendmail
    • rfc-ed
    • ietf
    • iana
    • usenet
    • fido
    • linux
    • kernel
    • google
    • ibm.com
    • fsf.
    • gnu
    • mit.e
    • bsd
    • math
    • unix
    • berkeley
    • foo.
    • mysqlruslis
    • nodomai
    • mydomai
    • example
    • inpris
    • borlan
    • sopho
    • panda
    • syma
    • avp
    • abuse
    • www
    • spam
    • spm
    • test
    • page
    • the.bat
    • gold-certs
    • feste
    • submit
    • not
    • help
    • service
    • privacy
    • somebody
    • soft
    • contact
    • site
    • rating
    • bugs
    • you
    • your
    • someone
    • anyone
    • nothing
    • nobody
    • noone
    • webmaster
    • postmaster
    • samples
    • info
    • root
      
      
15. Sends itself to email addresses gathered from the infected computer. The email has the following characteristics:
    
    From: (Spoofed)
    
    Subject: 12345
    
    Attachment: PlayGirls_2.exe
    
    Message Body:
    
    Hello [Random name]
    --
    Best regards,
    [Random name]

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. Update the virus definitions.
3. Restart the computer in Safe mode or Safe mode with Command Prompt.
4. Delete files added by the threat and run a system scan.
5. Restore files.
6. Reverse the changes made to the registry.
   

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

1. To disable 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"

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

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. To update 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 daily. 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.

3. To restart the computer in Safe mode or Safe mode with Command Prompt
Follow the instructions for your operating system.

Windows 95/98/Me
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."

Once in Safe mode (this could take some time) proceed with section 4.

Windows 2000

1. Shut down the computer, and then turn off the power. Wait for at least 30 seconds, and then restart the computer
2. When you see the black and white Starting Windows bar at the bottom of the screen, press the F8 key (usually on the top row of the keyboard).
3. In the Windows 2000 Advanced Options Menu, select Safe mode with Command Prompt, and then press Enter.
   
   Once the computer opens to a window with a command prompt (you should see a line of text and a blinking cursor), proceed with section 4.

Windows XP

1. Shut down the computer, and then turn off the power. Wait for at least 30 seconds, and then restart the computer. The computer begins processing a set of instructions known as the Basic Input/Output System (BIOS). What is displayed depends on the BIOS manufacturer. Some computers display a progress bar that refers to the word BIOS, while others may not display any indication that this process is occurring.
2. As soon as the BIOS has finished loading, begin tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears. If you begin tapping the F8 key too soon, some computers will display a "keyboard error" message. To avoid this, restart the computer and try again.
3. In the Windows 2000 Advanced Options Menu, select Safe mode with Command Prompt, and then press Enter.
   
   Once the computer opens to a window with a command prompt (you should see a line of text and a blinking cursor), proceed with section 4.

4. To delete files added by the threat and run a system scan
Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Do one of the following:
   • Windows 2000/XP: Skip to step b.
   • Windows 95/98/Me: Click Start > Run.
     
     
2. Type the following:
   
   cd
   cd windows
   del ___*
   cd system32
   del ___*
   cd program files orton antivirus
   navw32.exe/L
   
   Note: In del ___* above, "___" is three underscores.
   
   
3. Do one of the following:
   • Windows 2000/XP: Press Enter.
   • Windows 95/98/Me: Click OK.
     
     
4. Exit the command prompt.
   
5. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."

5. To restore files

1. Navigate to the ___b folder in the root directory of your infected Hard Disk (e.g. C:\___b )
   
2. Select all files and folders in the ___b folder except the folder [197 A characters], if it exists.
   
3. On the Taskbar click Edit > Copy
   
4. Go back to your root directory and click Edit > Paste
   
5. Delete the ___b folder.
   
   

6. To reverse the changes made to the registry
Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start > Run.
2. Type regedit
   
   Then click OK.
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the values:
   
   "Microsoft Synchronization Manager" = "___synmgr.exe"
   "Microsoft Windows DHCP" = "___r.exe"
   
   
5. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
   
   
6. In the right pane, delete the values:
   
   "Microsoft Synchronization Manager" = "___synmgr.exe"
   
   
7. Exit the Registry Editor.