WORM_SDBOT.AOU

Malware type: Worm

Aliases: Win32.Sdbot.GH

In the wild: Yes

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Description: 

This memory-resident worm spreads through network shares. It locates certain network shared folders, where it then attempts to drop a copy of itself.

It also takes advantage of the Windows LSASS Vulnerability to propagate across networks. This vulnerability allows remote code execution and enables a malicious user to gain full control of the affected system.

More information about this vulnerability can be found in the following page:

When run, this worm drops a copy of itself in the Windows system folder as the file MFIREWALL.EXE.

It also drops a component file MSDIRECTX.SYS, which Trend Micro detects as TROJ_ROOTKIT.H, in the same folder. This component file hides the worm's dropped copy from being seen by the user.

It also has backdoor capabilities, and may execute commands coming from a remote malicious user.

For additional information about this threat, see:

Description created: Feb. 14, 2005 5:09:36 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 63,161 Bytes

Ports used: Random

Initial samples received on: Feb 14, 2005

Compression type: FSG

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

Variant ofWORM_SDBOT.GEN

Related toTROJ_ROOTKIT.H

Payload 1: Performs backdoor routines

Details:

Installation and Autostart Techniques

Upon execution, this memory-resident worm drops a copy of itself in the Windows system folder as the file MFIREWALL.EXE.

It also drops a component file MSDIRECTX.SYS, which Trend Micro detects as TROJ_ROOTKIT.H, in the same folder. This component file hides the worm's dropped copy from being seen by the user.

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
SPAM FIREWALL = "mfirewall.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunServices
SPAM FIREWALL = "mfirewall.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
SPAM FIREWALL = "mfirewall.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\RunServices
SPAM FIREWALL = "mfirewall.exe"

As part of its installation routine, this worm also adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\Ole
SPAM FIREWALL = "mfirewall.exe"

HKEY_CURRENT_USER\System\CurrentControlSet\
Control\Lsa
SPAM FIREWALL = "mfirewall.exe"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\Lsa
SPAM FIREWALL = "mfirewall.exe"

It also adds the following registry keys on NT-based systems (Windows NT, 2000, and XP):

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Enum\Root\LEGACY_MSDIRECTX

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\msdirectx

It also modifies the following registry entries to the following values to make the affected system susceptible to its malicious intents:

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

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\Lsa
restrictanonymous = "dword:00000001"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SharedAccess
Start = "dword:00000004"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\wuauserv
Start = "dword:00000004"

Network Propagation and Exploit

This worm spreads through network shares. It locates certain network shared folders, where it then attempts to drop a copy of itself.

It also takes advantage of the Windows LSASS Vulnerability to propagate across networks. This vulnerability allows remote code execution and enables a malicious user to gain full control of the affected system.

More information about this vulnerability can be found in the following page:

Backdoor Capabilities

This worm comes with a built-in Internet Relay Chat (IRC) client, which allows it to connect to an IRC channel. It then opens a random port to enable a remote malicious user to perform the following actions:

  • Disable and enable DCOM
  • Disable and enable network shares
  • Download, execute and open files
  • List and terminate threads
  • Monitor channels
  • Obtain emails
  • Obtain pertinent system information
  • Perform basic IRC commands
  • Redirect TCP stream
  • Restrict and unrestrict access to IPC$
  • Send UDP packets to a remote user
  • Scan ports
  • Update the worm

Other Details

This worm is compiled using Visual C%20%20 and runs on Windows 95, 98, ME, NT, 2000, and XP.

Analysis By: Michael Stephen Tonido


SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.407.16

Pattern release date: Feb 14, 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:

IMPORTANT: Refer to the Clean Instructions for TROJ_ROOTKIT.H to completely remove this malware.

Restarting in Safe Mode

� On Windows 95

  1. Restart your computer.
  2. Press F8 at the Starting Windows 95 message.
  3. Choose Safe Mode from the Windows 95 Startup Menu then press Enter.

� On Windows 98 and ME

  1. Restart your computer.
  2. Press the CTRL key until the startup menu appears.
  3. Choose the Safe Mode option then press Enter.

� On Windows NT (VGA mode)

  1. Click Start>Settings>Control Panel.
  2. Double-click the System icon.
  3. Click the Startup/Shutdown tab.
  4. Set the Show List field to 10 seconds and click OK to save this change.
  5. Shut down and restart your computer.
  6. Select VGA mode from the startup menu.

� On Windows 2000

  1. Restart your computer.
  2. Press the F8 key, when you see the Starting Windows bar at the bottom of the screen.
  3. Choose the Safe Mode option from the Windows Advanced Options Menu then press Enter.

� On Windows XP

  1. Restart your computer.
  2. Press F8 after the Power-On Self Test (POST) is done. If the Windows Advanced Options Menu does not appear, try restarting and then pressing F8 several times after the POST screen.
  3. Choose the Safe Mode option from the Windows Advanced Options Menu then press Enter.

Note: After performing all the solutions for the removal of this malware, please restart your system normally, and run your Trend Micro antivirus product.

Removing Autostart Entries from the Registry

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

  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:
    SPAM FIREWALL = "mfirewall.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>RunServices
  5. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"
  6. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  7. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"
  8. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>RunServices
  9. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"

NOTE: If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Removing Other Malware Entries from the Registry

  1. Still in the Registry Editor, in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>System>CurrentControlSet>
    Control>Lsa
  2. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"
  3. In the left panel, double-click the following:
    HKEY_CURRENT_USER>System>CurrentControlSet>
    Control>Lsa
  4. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"
  5. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>Ole
  6. In the right panel, locate and delete the entry:
    SPAM FIREWALL = "mfirewall.exe"
  7. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>System>CurrentControlSet>
    Enum>Root
  8. Locate and delete the subkey:
    LEGACY_MSDIRECTX
  9. Still in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>System>CurrentControlSet>
    Services
  10. Locate and delete the subkey:
    msdirectx
  11. Close Registry 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 all files detected as WORM_SDBOT.AOU. To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro�s 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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