WORM_SDBOT.BSR

Malware type: Worm

Aliases: Backdoor.Win32.VanBot.f (Kaspersky), W32/Sdbot.worm (McAfee), W32.IRCBot (Symantec), BDS/VanBot.F.4 (Avira),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows NT, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Infection Channel 1 : Propagates via network shares


Description: 

This worm spreads via network shares. It generates IP addresses and spreads by attempting to drop a copy of itself in target addresses' default shares. If the said shares are password-protected, it uses gathered lists of user names and passwords as well as a hardcoded list of user names and passwords as its login credentials to gain access.

Using random TCP ports, it connects to an Internet Relay Chat (IRC) server and joins a specific channel, where it listens for commands from a remote malicious user. The said commands are executed locally on affected machines. This routine compromises system security and opens the affected machine to further attacks.

For additional information about this threat, see:

Description created: Nov. 14, 2006 7:55:00 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 655,360 Bytes

Ports used: Random TCP ports

Initial samples received on: Nov 6, 2006

Payload 1: Compromises system security

Payload 2: Disables services

Details:

Installation and Autostart Techniques

Upon execution, this worm drops a copy of itself as MGUARD.EXE in the Windows system folder.

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Ms Java for Windows NT = "mguard.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Ms Java for Windows NT = "mguard.exe"

It also modifies the following registry entries to ensure its automatic execution at every system startup:

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

(Note: The default value for the said entry is "Explorer.exe".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe, mguard.exe"

(Note: The default value for the said entry is "%System%\userinit.exe,". %System% is the Windows system folder, which is usually C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Registry Modifications

This worm adds itself in the Windows firewall exception list by creating the following registry entry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
SharedAccess\Parameters\FirewallPolicy\
StandardProfile\AuthorizedApplications\List
%Windows%\system\mguard.exe = "%Windows%\system\mguard.exe:*:Enabled:Ms Java for Windows NT"

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It also disables the DCOM protocol and restricts anonymous access to the affected system by modifying the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\OLE
EnableDCOM = "N"

(Note: The default value for the said registry entry is "Y".)

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\LSA
RestrictAnonymous = "1"

(Note: Though there is no default value for RestrictAnonymous, it may be modified from the one defined by the user.)

Propagation via Network Shares

This worm generates IP addresses and spreads by attempting to drop a copy of itself in the following target addresses' default shares:

  • ADMIN$
  • ADMIN$\system32
  • C$
  • C$\Windows\system32
  • C$\WINNT\system32
  • D$\Windows\system32
  • IPC$

If the said shares are password-protected, it uses the following list of hardcoded user names and passwords as its login credentials to gain access:

  • administrador
  • administrat
  • administrateur
  • administrator
  • admins
  • computer
  • database
  • default
  • guest
  • oracle
  • owner
  • staff
  • student
  • teacher
  • wwwadmin

Backdoor Capabilities

Using random TCP ports, this worm connects to an Internet Relay Chat (IRC) server and joins a specific channel, where it listens for the following commands from a remote malicious user:

  • Perform HTTP and FTP operations to download and execute files
  • Perform distributed denial of service (DDoS) flood attacks
  • Add or delete shares and files
  • Enable or disable DCOM
  • Redirect ports
  • Perform basic IRC operations
  • List, start, or terminate processes
  • Retrieve clipboard data
  • Capture image using webcam
  • Send email messages using its own SMTP engine
  • Retrieve cached passwords
  • Start a sniffer
  • Log keystrokes
  • Scan for vulnerable and/or infected systems
  • Retrieve system information
  • Flush the DNS cache

It executes these commands locally on an affected system, providing the remote user virtual control over the affected system. This routine compromises system security and opens the affected machine to further attacks.

Affected Platforms

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

Analysis By: Elizabeth R. Viray


SOLUTION


Minimum scan engine version needed: 8.000

Pattern file needed: 3.905.00

Pattern release date: Nov 6, 2006


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:

Terminating the Malware Program

This procedure terminates the running malware process.

  1. Open Windows Task Manager.
    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:
    MGUARD.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 computer.
  4. To check if the malware process has been terminated, close Task Manager, and then open it again.
  5. Close Task Manager.

*NOTE: On computers running all Windows platforms, if the process you are looking for is not in the list displayed by Task Manager or Process Explorer, continue with the next solution procedure, noting additional instructions. If the malware process is in the list displayed by either Task Manager or Process Explorer, but you are unable to terminate it, restart your computer in safe mode.

Editing the Registry

This malware modifies the computer'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 NT 4.0
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  3. 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:
    Ms Java for Windows NT = "mguard.exe"
  4. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  5. In the right panel, locate and delete the entry:
    Ms Java for Windows NT = "mguard.exe"

Removing Other Entry from the Registry

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>Services>
    SharedAccess>Parameters>FirewallPolicy>
    StandardProfile>AuthorizedApplications>List
  2. In the right panel, locate and delete the following entries:
    %Windows%\system\mguard.exe = "%Windows%\system\mguard.exe:*:Enabled:Ms Java for Windows NT"
    (Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Restoring Modified Entries from the Registry

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows NT>CurrentVersion>Winlogon
  2. In the right panel, locate the following:
    Shell = "Explorer.exe mguard.exe"
  3. Right-click on the value name and choose Modify. Change the value data of this entry to:
    "Explorer.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows NT>CurrentVersion>Winlogon
  5. In the right panel, locate the following:
    Userinit = "%System%\userinit.exe, mguard.exe"
    (Note: %System% is the Windows system folder, which is usually C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
  6. Right-click on the value name and choose Modify. Change the value data of this entry to:
    "%System%\userinit.exe,"

Restoring EnableDCOM and RestrictAnonymous Registry Entries

This malware modifies EnableDCOM and RestrictAnonymous registry entries to a certain value. To know more about restoring these registries to their original values, please refer to these articles:

  1. COM security frequently asked questions
  2. How to disable DCOM support in Windows
  3. How to Use the RestrictAnonymous Registry Value in Windows 2000
  4. The "RestrictAnonymous" Registry Value May Break the Trust to a Windows 2000 Domain

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

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Ole
  2. In the right panel, locate the entry:
    EnableDCOM = "N"
  3. Right-click on this registry entry and choose Modify. Change the value of this entry to:
    "Y"
  4. Close Registry Editor.

Important Windows XP Cleaning Instructions

Users running Windows XP must disable System Restore to allow full scanning of infected computers.

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

Running Trend Micro Antivirus

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

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




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