WORM_AKBOT.M

Malware type: Worm

Aliases: Backdoor.Win32.Akbot.a (Kaspersky), W32/Akbot (McAfee), Backdoor.Trojan (Symantec), BDS/Akbot.A (Avira), W32/Akbot-C (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 98, ME, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Medium

Infection Channel 1 : Propagates via software vulnerabilities


Description: 

This worm spreads by taking advantage of the Windows vulnerability whose description is found in the following Microsoft Web page:

Using varying ports, it connects to certain Internet Relay Chat (IRC) servers and joins a specific channel, where it listens for commands from a remote malicious user. The said commands are executed locally on affected machines.

It also prevents a user access to several antivirus and security Web sites by redirecting connection to the local machine.

For additional information about this threat, see:

Description created: Feb. 7, 2006 3:33:43 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: Varies

Ports used: Varies

Initial samples received on: Feb 5, 2006

Compression type: Petite

Vulnerability used:  (MS04-007) ASN.1 Vulnerability Could Allow Code Execution

Payload 1: Compromises system security

Payload 2: Modifies HOSTS file

Details:

Installation and Autostart Technique

This memory-resident worm arrives on a system as a .DLL file dropped or installed by other malware.

Upon execution, it drops any of the following copies of itself into the Windows system folder:

  • scvhost32.dll
  • steam.dll

It sets the dropped file's attributes to Hidden and System to avoid easy detection.

It creates any of the following registry entries, corresponding to the dropped copy, to ensure its automatic execution at every Windows startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
WinDLL (steam.dll) = "rundll32.exe %System%\steam.dll,start"
WinDLL (scvhost32.dll) = "rundll32.exe %System%\scvhost32.dll,start"

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Propagation Routine

This worm takes advantage of the Windows ASN.1 vulnerability to propagate across networks. For more information regarding the said vulnerability, refer to the following Microsoft Web page:

Backdoor Capabilities

Using varying ports, this worm connects to the Internet Relay Chat (IRC) server, root.the-an.us or lsd2.danknugs.be, then joins a specific channel, where it listens for the following commands from a remote malicious user:

  • Retrieve various network and system information
  • Download files
  • Perform denial of service (DoS) attacks using various flooding methods
  • Perform port scanning

The said routine provides the remote malicious user virtual control over the affected system, thus compromising system security.

HOSTS File Modification

This worm also overwrites the system's HOSTS file, which contains host name to IP address mappings. It accesses the said HOSTS file in the following folder:

    %System%\drivers\etc

Note that systems running on Windows 98 and ME are unaffected by this routine since this worm only targets the HOSTS file in the %System%\drivers\etc folder.

The said routine is done so that the following Web sites, which are usually related to antivirus companies, can no longer be accessed by affected users:

  • avp.com
  • ca.com
  • customer.symantec.com
  • dispatch.mcafee.com
  • download.mcafee.com
  • f-secure.com
  • kaspersky-labs.com
  • kaspersky.com
  • liveupdate.symantec.com
  • liveupdate.symantecliveupdate.com
  • mast.mcafee.com
  • mcafee.com
  • microsoft.com
  • my-etrust.com
  • nai.com
  • networkassociates.com
  • pandasoftware.com
  • rads.mcafee.com
  • secure.nai.com
  • securityresponse.symantec.com
  • sophos.com
  • symantec.com
  • trendmicro.com
  • update.microsoft.com
  • update.symantec.com
  • updates.symantec.com
  • us.mcafee.com
  • viruslist.com
  • virustotal.com
  • www.avp.com
  • www.ca.com
  • www.f-secure.com
  • www.grisoft.com
  • www.kaspersky.com
  • www.mcafee.com
  • www.microsoft.com
  • www.my-etrust.com
  • www.nai.com
  • www.networkassociates.com
  • www.pandasoftware.com
  • www.sophos.com
  • www.symantec.com
  • www.trendmicro.com
  • www.viruslist.com
  • www.virustotal.com

Affected Platforms

This worm runs on Windows 98, ME, 2000, XP, and Server 2003.

Analysis By: Ricardo C. Robielos III

Updated By: Erwin Boy-Ang Balunsat

Revision History:

 

Feb 8, 2006 - Modified Virus Report

SOLUTION


Minimum scan engine version needed: 7.000

Pattern file needed: 3.196.04

Pattern release date: Feb 5, 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:

AUTOMATIC REMOVAL INSTRUCTIONS

MANUAL REMOVAL INSTRUCTIONS

Restarting in Safe Mode

This malware has characteristics that require the computer to be restarted in safe mode. Go to this page for instructions on how to restart your computer in safe mode.

Enabling Show All Files

This procedure allows you to access hidden malware files using Windows Explorer.

• On Windows 98

  1. Open Windows Explorer. Right-click Start then click Explore.
  2. On the View menu, click Options or Folders Options.
  3. Click the View tab.
  4. Select Show all files, then click OK.

• On Windows ME, 2000, XP, and Server 2003

  1. Open Windows Explorer. Right-click Start then click Explore.
  2. On the Tools menu, click Folder Options.
  3. Click the View tab.
  4. Select Show hidden files and folders, then click OK.

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 95, Windows 98, and Windows ME
  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 entries:
    • WinDLL (steam.dll) = "rundll32.exe %System%\steam.dll,start"
    • WinDLL (scvhost32.dll) = "rundll32.exe %System%\scvhost32.dll,start"
      (Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
  4. Close Registry Editor.

Removing Malware Entries from the HOSTS File

Deleting malware entries from the HOSTS file removes all malware-made changes on host name association.

  1. Open the following file using a text editor (such as NOTEPAD):
      %System%\drivers\etc\HOSTS
  2. Delete the following entries:
    • 127.0.0.1 www.symantec.com
    • 127.0.0.1 securityresponse.symantec.com
    • 127.0.0.1 symantec.com
    • 127.0.0.1 www.sophos.com
    • 127.0.0.1 sophos.com
    • 127.0.0.1 www.mcafee.com
    • 127.0.0.1 mcafee.com
    • 127.0.0.1 liveupdate.symantecliveupdate.com
    • 127.0.0.1 www.viruslist.com
    • 127.0.0.1 viruslist.com
    • 127.0.0.1 viruslist.com
    • 127.0.0.1 f-secure.com
    • 127.0.0.1 www.f-secure.com
    • 127.0.0.1 kaspersky.com
    • 127.0.0.1 kaspersky-labs.com
    • 127.0.0.1 www.avp.com
    • 127.0.0.1 www.kaspersky.com
    • 127.0.0.1 avp.com
    • 127.0.0.1 www.networkassociates.com
    • 127.0.0.1 networkassociates.com
    • 127.0.0.1 www.ca.com
    • 127.0.0.1 ca.com
    • 127.0.0.1 mast.mcafee.com
    • 127.0.0.1 my-etrust.com
    • 127.0.0.1 www.my-etrust.com
    • 127.0.0.1 download.mcafee.com
    • 127.0.0.1 dispatch.mcafee.com
    • 127.0.0.1 secure.nai.com
    • 127.0.0.1 nai.com
    • 127.0.0.1 www.nai.com
    • 127.0.0.1 update.symantec.com
    • 127.0.0.1 updates.symantec.com
    • 127.0.0.1 us.mcafee.com
    • 127.0.0.1 liveupdate.symantec.com
    • 127.0.0.1 customer.symantec.com
    • 127.0.0.1 rads.mcafee.com
    • 127.0.0.1 trendmicro.com
    • 127.0.0.1 pandasoftware.com
    • 127.0.0.1 www.pandasoftware.com
    • 127.0.0.1 www.trendmicro.com
    • 127.0.0.1 www.grisoft.com
    • 127.0.0.1 www.microsoft.com
    • 127.0.0.1 microsoft.com
    • 127.0.0.1 update.microsoft.com
    • 127.0.0.1 www.virustotal.com
    • 127.0.0.1 virustotal.com
  3. Save the file and close the text editor.

Deleting Malware Files

  1. Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
  2. In the Named input box, type:
    scvhost32.dll
  3. In the Look In drop-down list, select the drive that contains Windows, then press Enter.
  4. Once located, select the file then press Delete.
  5. Repeat steps 2-4 to delete the following file:
    steam.dll

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and 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_AKBOT.M. 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.

Applying Patch

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




Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.