WORM_AUTORUN.SLS

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 ALIASES:

Trojan:Win32/SystemHijack.D (Microsoft), Packed.Win32.Klone.af (Kaspersky), W32.SillyFDC (Symantec),

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives by connecting affected removable drives to a system. 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.

It modifies certain registry entries to hide Hidden files.

  TECHNICAL DETAILS

File Size:

40,448 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Apr 2011

Arrival Details

This worm arrives by connecting affected removable drives to a system.

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:

  • %System%\SVSH0ST.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 component file(s):

  • %System%\Autorun.inf

(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.)

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
svchost = "%System%\SVSH0ST.EXE"

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
WindowsUpdate
DisableWindowsUpdateAccess = "1"

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel
HomePage = "1"

File Infection

This worm infects the following file types:

  • .asp
  • .htm
  • .html
  • .php
  • .jsp
  • .aspx

Propagation

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

  • niu.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]

open=niu.exe
shell\open=´ò¿ª(&O)
shell\open\Command=niu.exe
shell\open\Default=1
shell\explore=×ÊÔ´¹ÜÀíÆ÷(&X)
shell\explore\Command=niu.EXE

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}om.com/TJ.asp
  • http://{BLOCKED}om/xia.exe
  • http://{BLOCKED}om/wangma.exe

It modifies the following registry entries to hide Hidden files:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "3"

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

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and terminate files detected as WORM_AUTORUN.SLS

[ Learn More ]
  1. 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.
  2. 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
    • svchost = "%System%\SVSH0ST.EXE"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\WindowsUpdate
    • DisableWindowsUpdateAccess = "1"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • HomePage = "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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "3"
      To: CheckedValue = 1

Step 5

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.  %System%\Autorun.inf

Step 6

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

[ Learn More ]
DATA_GENERIC
  • If the lines are present, delete the file.
  • Repeat steps 3 to 6 for the remaining AUTORUN.INF files in other remaining removable drives.
  • Close Search Results.

    • Step 7

    Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.SLS. 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 8

    Restore deleted/modified files and/or registry entries from backup

    *Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.


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