Analysis by: Clive Fuentebella
ALIASES:

Worm:Win32/Autorun.NN (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Worm 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 does not have any backdoor routine.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size: 36,864 bytes
File Type: EXE
Memory Resident: Yes
Payload: Modifies system registry

Arrival Details

This Worm 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%\EXPLORER.EXE
  • %System%\wsctf.exe
  • {Removable drive}:\EXPLORER.EXE
  • {Removable drive}:\wsctf.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This Worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
wsctf.exe = wsctf.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
EXPLORER.EXE = EXPLORER.EXE

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = userinit.exe,EXPLORER.EXE

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
gshost

Propagation

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

Backdoor Routine

This Worm does not have any backdoor routine.

Rootkit Capabilities

This Worm does not have rootkit capabilities.

Information Theft

This Worm does not have any information-stealing capability.

Other Details

This Worm does the following:

  • It continuously terminates processes with the following strings in their window names:
    • Audition
    • Counter-Strike
    • Crazy Arcade
    • CTRacer Client
    • legend of mir2
    • NFS Underground 2
    • O2-JAM
    • PopKart Client
    • QQGame
    • QQ幻想1.64
    • QQ幻想1.65
    • QQ幻想1.66
    • QQ幻想1.67
    • Warcraft III
    • YB_OnlineClient
    • 三国策
    • 俥・
    • 大话西游
    • 大话西游 II (revision 37230)
    • 大话西游 II (revision 37231)
    • 大话西游 II (revision 37232)
    • 封神榜·网络版
    • 梦幻国度
    • 梦幻西游ONLINE
    • 浩方对战平台
    • 街头篮球
    • 魔兽世界
    • 﨣S・
  • The malicious AUTORUN.INF contains the following strings:
    • [autorun]
      OPEN=EXPLORER.EXE
      shell\open=打开(&O)
      shell\open\Command=EXPLORER.EXE
      shell\open\Default=1
      shell\explore=资源管理器(&X)
      shell\explore\Command=EXPLORER.EXE

NOTES:

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.576.03
FIRST VSAPI PATTERN DATE: 05 Mar 2021
VSAPI OPR PATTERN File: 16.577.00
VSAPI OPR PATTERN Date: 06 Mar 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • wsctf.exe=wsctf.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • EXPLORER.EXE=EXPLORER.EXE
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Userinit=userinit.exe,EXPLORER.EXE

Step 5

Search and delete these files

[ 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.
  • %System%\EXPLORER.EXE
  • %System%\wsctf.exe
  • {Removable drive}:\EXPLORER.EXE
  • {Removable drive}:\wsctf.exe

Step 6

Search and delete AUTORUN.INF files created by Worm.Win32.JAMPORK.A that contain these strings

[ Learn More ]
[autorun]
OPEN=EXPLORER.EXE
shell\open=打开(&O)
shell\open\Command=EXPLORER.EXE
shell\open\Default=1
shell\explore=资源管理器(&X)
shell\explore\Command=EXPLORER.EXE

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.JAMPORK.A. 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.


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