Modified by: Rhena Inocencio
ALIASES:

Mal/SillyFDC-A (Sophos), W32/Nahkos.A (Panda), a variant of Win32/Malas worm (Nod32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via removable drives, Propagates via peer-to-peer networks

This worm arrives via peer-to-peer (P2P) shares. It arrives via removable drives. It arrives by accessing affected shared networks. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size: 340,195 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 Apr 2012

Arrival Details

This worm arrives via peer-to-peer (P2P) shares.

It arrives via removable drives.

It arrives by accessing affected shared networks.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Temp%\svchost.exe
  • %User Profile%\userinit.exe
  • %Windows%\Web\OfficeUpdate.exe
  • %Program Files%\Common Files\Microsoft Shared\MSshare.exe
  • %All Users Profile%\Start Menu\Programs\Startup\AdobeUpdate.exe
  • %Program Files%\XPCode\SexGame.exe
  • %Program Files%\XPCode\SEXGAMELIST.PIF
  • %Program Files%\XPCode\SEXSCREENSAVER.SCR

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

It drops the following files:

  • %Windows%\Tasks\At1.job

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

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SoundMax = "%User Profile%\userinit.exe"

Other System Modifications

This worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\SystemRestore
DisableConfig = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\SystemRestore
DisableSR = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
Nofolderoptions = "1"

It modifies the following registry entries:

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

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

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

(Note: The default value data of the said registry entry is 0.)

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

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

Propagation

This worm drops copies of itself into the following folders used in peer-to-peer (P2P) networks:

  • Kazaa Lite\My Shared Folder
  • Kazaa\My Shared Folder
  • Edonkey2000\Incoming
  • Icq\Shared Files
  • emule\incoming
  • Gnucleus\Downloads\Incoming
  • KMD\My Shared Folder
  • Limewire\Shared

It drops the following copy of itself in all physical and removable drives:

  • autoply.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
action=Open Drive
open=autoply.exe OPEN
icon=C:\windows\system32\shell32.dll,8
shell\open=Open
shell\open\Command=autoply.exe OPEN
shell\open\Default=1
shell\explore=Explore
shell\explore\Command=autoply.exe EXPLORE
shell\AutoPlay=AutoPlay
shell\AutoPlay\Command=autoply.exe OPEN

Other Details

This worm does the following:

  • It deletes the following registry enries:
    HKEY_CLASSES_ROOT\InternetShortcut
    IsShortcut = ""
    HKEY_CLASSES_ROOT\lnkfile
    IsShortcut = ""
    HKEY_CLASSES_ROOT\piffile
    IsShortcut = ""
  • It uses the following filenames when dropping a copy in P2P folders:
    Sex_ScreenSaver.scr
    Sex_Game.exe

NOTES:

It modifies the following .LNK files to point to its copy:

  • %All Users Profile%\Start Menu\Programs\Accessories\Calculator.lnk
  • %All Users Profile%\Start Menu\Programs\Accessories\Paint.lnk
  • %Start Menu%\Programs\Accessories\Command Prompt.lnk
  • %Start Menu%\Programs\Accessories\Notepad.lnk

It drops the following .LNK files which point to its copy:

  • %All Users Profile%\Start Menu\Programs\Startup\OFFICE UPDATE.LNK
  • %Program Files%\XPCode\Games.lnk

It also drops a copy of itself in mapped drives. It drops a copy of itself in the folder %System Root%\Inetpub\ftproot, which is the root folder for FTP servers.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.908.03
FIRST VSAPI PATTERN DATE: 13 Apr 2012
VSAPI OPR PATTERN File: 8.909.00
VSAPI OPR PATTERN Date: 14 Apr 2012

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and terminate files detected as WORM_AUTORUN.LFR

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • SoundMax = "%User Profile%\userinit.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore
    • DisableConfig = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore
    • DisableSR = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • Nofolderoptions = "1"

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = "2"
      To: HideFileExt = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = "2"
      To: ShowSuperHidden = "1"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Program Files%\XPCode

Step 6

Search and delete this file

[ Learn More ]

There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %All Users Profile%\Start Menu\Programs\Startup\OFFICE UPDATE.LNK

Step 7

Search and delete AUTORUN.INF files created by WORM_AUTORUN.LFR that contain these strings

[ Learn More ]
[autorun]
action=Open Drive
open=autoply.exe OPEN
icon=C:\windows\system32\shell32.dll,8
shell\open=Open
shell\open\Command=autoply.exe OPEN
shell\open\Default=1
shell\explore=Explore
shell\explore\Command=autoply.exe EXPLORE
shell\AutoPlay=AutoPlay
shell\AutoPlay\Command=autoply.exe OPEN

Step 8

Delete the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

  1. Open the Windows Scheduled Tasks. To do this:
    • On Windows 2000, XP, and Server 2003:
      Click on Start>Programs>Accessories>System Tools>Scheduled Tasks
    • On Windows Vista and 7:
      Click Start>All Programs>Accessories>System Tools>Task Scheduler
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the job file. To do this:
    • On Windows 2000, XP, and Server 2003:
      Check the value in the Run field
    • On Windows Vista and 7:
      Find the malware path and file name in the Details column of the Action tab
  4. If the above conditions are true, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

Step 9

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.LFR. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 10

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result. DATA_GENERIC
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.

    • • For Windows Vista and Windows 7 users:

    1. Click Start>Computer.
    2. In the Search input box, type the following:
      DATA_GENERIC
    3. Once located, select the file then press SHIFT+DELETE to delete it.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    NOTES:

    Do the following step as part of Step 4:

    Restore deleted registry entries

    1. Still in Registry Editor, in the left panel, double-click the following:

    HKEY_CLASSES_ROOT\InternetShortcut

    2. In the right panel, Right-click and choose New String Value. Name the new value as:

    IsShortcut = ""

    3. Repeat steps 1 and 2 to the following registry keys:

    • HKEY_CLASSES_ROOT\lnkfile
    • HKEY_CLASSES_ROOT\piffile

    4. Close Registry Editor.

    Before scanning:

    1. Restore the Target Path of the following .LNK files modified by this malware:

    • %All Users Profile%\Start Menu\Programs\Accessories\Calculator.lnk
    • %All Users Profile%\Start Menu\Programs\Accessories\Paint.lnk
    • %Start Menu%\Programs\Accessories\Command Prompt.lnk
    • %Start Menu%\Programs\Accessories\Notepad.lnk

    a. Right click on the file

    b. Select Properties

    c. Type the original Target Path and then click Apply:

    For Calculator.lnk: %System%\calc.exe

    For Paint.lnk: %System%\mspaint.exe

    For Command Prompt.lnk: %System%\cmd.exe

    For Notepad.lnk: %System%\notepad.exe


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