Analysis by: Noel Anthony Llimos

ALIASES:

Worm:Win32/Fadok!rfn (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 1,636,352 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Apr 2019

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 adds the following folders:

  • %Application Data\RAC

It drops the following files:

  • {Current Directory}\{Malware File Name}.xlsx
  • %Application Data\RAC\mls.exe
  • %Application Data%\RAC\svcsc.exe.config
  • %Application Data%\RAC\svcsc.exe.tmp
  • %Application Data%\RAC\svcsc.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It adds the following processes:

  • "%Application Data\RAC\mls.exe" -s

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
mls = "%Application Data\RAC\mls.exe" -s

Propagation

This Worm drops the following copy(ies) of itself in all removable drives:

  • {Drive}\{File Name of a file Inside the Drive}.exe

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.960.03
FIRST VSAPI PATTERN DATE: 25 Apr 2019
VSAPI OPR PATTERN File: 14.961.00
VSAPI OPR PATTERN Date: 26 Apr 2019

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
    • mls = "%Application Data\RAC\mls.exe" -s

Step 5

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.
  • {Current Directory}\{Malware File Name}.xlsx
  • {Drive}\{File Name of a file Inside the Drive}.exe
  • %Application Data\RAC\mls.exe
  • %Application Data%\RAC\svcsc.exe.config
  • %Application Data%\RAC\svcsc.exe.tmp
  • %Application Data%\RAC\svcsc.exe

Step 6

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.
  • %Application Data\RAC

Step 7

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