Analysis by: Maureen Reyes
 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

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.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 608,768 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Jun 2019
Payload: Steals information

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%\{Malware Filename}.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).)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Remcos_Mutex_Inj
  • Remcos-Y177HO

Other System Modifications

This Backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Remcos-Y177HO

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Remcos-Y177HO
exepath = "{random characters}"

HKEY_CURRENT_USER\Software\Remcos-Y177HO
licence = "{BLOCKED}01EA3B3551E54FC2DB8E57DB55"

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Perform ping
  • Enumerate drives
  • List all files
  • Open file/s
  • Get file/s from affected computer
  • Upload file/s to affected computer
  • Delete file/s from affected computer
  • Rename file/s from affected computer
  • Create new directory
  • Search a file from affected computer
  • Download file from url
  • Download file from local
  • Enumerate process
  • Terminate process
  • Maximize/Minimize application
  • Switch application
  • Terminate application
  • Open cmd
  • Open webpage
  • Open screen capture
  • Open keylogger
  • Set affected computer to send logs automatically
  • Deletes cookies and stored browser logins
  • Get screenshot
  • Capture image from camera if available
  • Capture voice from mic if available
  • Acquire user password
  • Display a messagebox to affected computer
  • Sends keyboard input
  • Sends mouse click
  • Shutdown affected Computer
  • Copy clipboard data
  • Set clipboard data
  • Clear clipboard data
  • Manipulate registry entries

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}4.31.74

Other Details

This Backdoor does the following:

  • This Backdoor gathers the following information and reports it to its servers:
    Computer Name
    Operating System Version
    Product Name
    Primary Adapter
    User Access (Admin or Non-admin)
    User Profile
    User Name
    User Domain
    Processor Revision No.
    Processor Level
    Processor Identifier
    Processor Architecture
    System Type (32-bit or 64-bit)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.196.03
FIRST VSAPI PATTERN DATE: 25 Jun 2019
VSAPI OPR PATTERN File: 15.197.00
VSAPI OPR PATTERN Date: 26 Jun 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

Identify and terminate files detected as Backdoor.Win32.REMCOS.TIOIBEAS

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software
    • Remcos-Y177HO

Step 5

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\Remcos-Y177HO
    • exepath = {random characters}
  • In HKEY_CURRENT_USER\Software\Remcos-Y177HO
    • licence = DD36B901EA3B3551E54FC2DB8E57DB55

Step 6

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.REMCOS.TIOIBEAS. 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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