Analysis by: John Anthony Banes
ALIASES:

Worm:VBS/Slogod.B (Microsoft); VBS.Solow (Norton); VBS:Solow-L (Avast)

 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: Via physical/removable drives, Dropped by other malware, Downloaded from the Internet

This Worm arrives via removable drives. 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: 3,796 bytes
File Type: VBS
Memory Resident: Yes
Initial Samples Received Date: 04 Mar 2019
Payload: Displays windows

Arrival Details

This Worm arrives via removable drives.

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:

  • %Windows%\maskrider2001.vbs

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

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
maskrider = %Windows%\maskrider2001.vbs

Other System Modifications

This Worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Window Title = TAGA ESTI, MARINDUQUE MABUHAY!!!

Propagation

This Worm drops copies of itself in the following drives:

  • {fixed drive letter}:\maskrider2001.vbs
  • {removable drive letter}:\maskrider2001.vbs (except drive A:)

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]
shellexecute=wscript.exe maskrider2001.vbs

NOTES:

This worm creates registry entries that changes the text displayed in the title bar of Internet Explorer.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.852.02
FIRST VSAPI PATTERN DATE: 05 Mar 2019
VSAPI OPR PATTERN File: 14.853.00
VSAPI OPR PATTERN Date: 06 Mar 2019

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

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • maskrider = %Windows%\maskrider2001.vbs
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Window Title = TAGA ESTI, MARINDUQUE MABUHAY!!!

Step 5

Search and delete AUTORUN.INF files created by Worm.VBS.SOLOW.A that contain these strings

[ Learn More ]
  • [autorun]
  • shellexecute=wscript.exe maskrider2001.vbs

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.VBS.SOLOW.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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