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Trojan.Win32.KILLAV.WLEAT

March 04, 2022
 Analysis by: Nathaniel Gregory Ragasa
 ALIASES:

Trojan:Win32/Farfli.CM!MTB(MICROSOFT), DS:Backdoor.Win32.Farfli.gen(KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan 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:

79,308,288 bytes

File Type:

EXE

Memory Resident:

No

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %Program Files%\Edge\Microsoft\EdgeUpdat\EdgeUpdateTaskMachineUA.exe → copy of itself
  • %Public%\Documents\pass.txt

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

It adds the following processes:

  • "%Program Files%\Edge\Microsoft\EdgeUpdat\EdgeUpdateTaskMachineUA.exe"

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Rsymwg ccyqksqc
ConnectGroup = mofa

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Rsymwg ccyqksqc
MarkTime = {Date when the file is executed}

Other Details

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\Rsymwg ccyqksqc

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.418.08

FIRST VSAPI PATTERN DATE:

03 Mar 2022

VSAPI OPR PATTERN File:

17.419.00

VSAPI OPR PATTERN Date:

04 Mar 2022

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

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\SYSTEM\ControlSet001\services\Rsymwg ccyqksqc
    • ConnectGroup = mofa
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\Rsymwg ccyqksqc
    • MarkTime = {Date when the file is executed}

Step 4

Delete this registry key

[ 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\SYSTEM\ControlSet001\services\
    • Rsymwg ccyqksqc

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.
  • %Program Files%\Edge\Microsoft\EdgeUpdat\EdgeUpdateTaskMachineUA.exe
  • %Public%\Documents\pass.txt

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.KILLAV.WLEAT. 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 the following Trend Micro Support pages for more information:


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