WORM_AUTORUN.BKK

Malware type: Worm

Aliases: Trojan.Win32.Inject.ldi (Kaspersky), Generic PWS.ak (McAfee), Trojan Horse (Symantec), TR/Crypt.XPACK.Gen (Avira), W32/Backdoor2.DSUF (exact) (F-Prot), Worm:Win32/Taterf.B (Microsoft)

In the wild: Yes

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Low

Distribution potential:

High

Infection Channel 1 : Propagates via removable drives


Infection Channel 2 : Copies itself in all available physical drives


Description: 

A worm is a malware that is designed to propagate and spread across networks. Worms are known to propagate using one or several of different transmission vectors like email, IRC, network shares, instant messengers (IM), and peer-to-peer (P2P) networks.

Worms do not infect files, but may carry one or more payloads, such as computer security compromise and information theft.

Worms typically modify system settings to automatically start. Users may need to terminate worms before they can be deleted. Also, restoring affected systems may require procedures other than scanning with an antivirus program.

For additional information about this threat, see:

Description created: Dec. 24, 2008 9:31:15 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  No

Size of malware: 107,045 Bytes

Initial samples received on: Dec 24, 2008

Details:

Installation and Autostart Techniques

This worm drops a copy of itself as:

  • %System%\kamsoft.exe

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

It drops the following possibly malicious component files:

  • %System%\gasretyw0.dll
  • %System%\vamsoft.exe
  • %System%\vbsdfe0.dll

The dropped .DLL files are injected into all running applications as part of its memory residency technique.

This worm creates the following registry entries to automatically execute itself and a dropped component file at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
kamsoft = "%System%\kamsoft.exe"

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
vamsoft = "%system%\vamsoft.exe"

Other System Modifications

It modifies the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Explorer\Advanced
Hidden = "2"

(Note: The default value data for the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Explorer\Advanced
ShowSuperHidden = "0"

(Note: The default value data for the said registry entry is 1.)

Propagation via Physical/Removable/Floppy Drives

This worm drops copies of itself in all physical and removable drives. It also drops an AUTORUN.INF file to automatically execute dropped copies when the drives are accessed.

The dropped AUTORUN.INF file contains the following strings:

[random characters]
[AutoRun]
[random characters]
open=m9ma.exe
[random characters]
shell\open\Command=m9ma.exe
[random characters]
shell\open\Default=1
[random characters]
shell\explore\Command=m9ma.exe
[random characters]

Other Details

This worm deletes itself after execution.

Analysis By: Erika Mendoza

Revision History:

First pattern file version: 7.938.08
First pattern file release date: Mar 29, 2011

SOLUTION


Minimum scan engine version needed: 8.700

Pattern file needed: 8.360.12

Pattern release date: Aug 17, 2011


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 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).

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.

Removing Autostart Entries from the Registry

This solution deletes/modifies registry entries added/modified by this malware. Before performing the steps below, make sure you know how to back up the registry and how to restore it if a problem occurs. Refer to this Microsoft article for more information about modifying your computer's registry.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>Windows>
    CurrentVersion>
  3. In the right panel, locate and delete the entry:
    • kamsoft = "%System%\kamsoft.exe"
    • vamsoft = "%System%\vamsoft.exe"
    (Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Restoring Registry Entries

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>
    Explorer>Advanced
  2. In the right panel, locate the entry:
    Hidden = "2"
  3. Right-click on the value name and choose Modify. Change the value data of this entry to:
    1
  4. In the right panel, locate the entry:
    ShowSuperHidden = "0"
  5. Right-click on the value name and choose Modify. Change the value data of this entry to:
    1
  6. Close Registry Editor.

Deleting the Malware File(s)

  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:
    %System%\gasretyw0.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 SHIFT%20DELETE.
  5. Repeat steps 2-4 for the following files:
    • %System%\vamsoft.exe
    • %System%\vbsdfe0.dll

Deleting Malware-created AUTORUN.INF/s

  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:
    AUTORUN.INF
  3. In the Look In drop-down list, select a drive, then press Enter.
  4. Select the file, then open using Notepad.
  5. Check if the following lines are present in the file:
    [random characters]
    [AutoRun]
    [random characters]
    open=m9ma.exe
    [random characters]
    shell\open\Command=m9ma.exe
    [random characters]
    shell\open\Default=1
    [random characters]
    shell\explore\Command=m9ma.exe
    [random characters]
  6. If the lines are present, delete the file.
  7. Repeat steps 3 to 6 for AUTORUN.INF files in the remaining removable drives.
  8. Close Search Results.

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_AUTORUN.BKK. 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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