Backdoor.Win32.REMCOS.MANEAGEQ

January 27, 2020
 Analysis by: Joshua John Bantayan
 ALIASES:

HEUR:Trojan.Win32.Hesv.gen (KASPERSKY); Trojan.Win32.Crypt, Trojan.Win32.Crypt (IKARUS)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

1,124,691 bytes

File Type:

EXE

Initial Samples Received Date:

20 Jan 2020

Arrival Details

This Backdoor 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 Backdoor adds the following processes:

  • %User Temp%\Afenc\Afenvym
  • %System%\TapiUnattend.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %User Temp%\Afenc

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Afen = %AppDataLocal%\Afen\Afen_setko.hta

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software
EXEpath = {Random Characters}

Dropping Routine

This Backdoor drops the following files:

  • %User Temp%\Afenc.lnk
  • %User Temp%\Afenc\Afen
  • %User Temp%\Afenc\Afenvym.exe
  • %AppDataLocal%\Afen\Afen
  • %AppDataLocal%\Afen\Afen_setko.hta
  • %AppDataLocal%\Afen\Afenoet.vbs
  • %AppDataLocal%\Afen\Afenrwe.exe
  • %Application Data%\click\log.dat

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.{BLOCKED}80.205:42018

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.632.04

FIRST VSAPI PATTERN DATE:

20 Jan 2020

VSAPI OPR PATTERN File:

15.633.00

VSAPI OPR PATTERN Date:

21 Jan 2020

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
    • Afen = %AppDataLocal%\Afen\Afen_setko.hta
  • In HKEY_CURRENT_USER\Software
    • EXEpath = {Random Characters}

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.  
  • %User Temp%\Afenc.lnk
  • %User Temp%\Afenc\Afen
  • %User Temp%\Afenc\Afenvym.exe
  • %AppDataLocal%\Afen\Afen
  • %AppDataLocal%\Afen\Afen_setko.hta
  • %AppDataLocal%\Afen\Afenoet.vbs
  • %AppDataLocal%\Afen\Afenrwe.exe
  • %Application Data%\click\log.dat

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.REMCOS.MANEAGEQ. 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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