PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size: 867,067 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 12 Oct 2017

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 creates the following folders:

  • %User Profile%\Application Data\remcos

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

Other System Modifications

This Backdoor deletes the following files:

  • %System Root%\aspr_keys.ini

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\remcos_vhdqryacimorztk

It adds the following registry entries:

HKEY_CURRENT_USER\Software\remcos_vhdqryacimorztk
EXEpath = "r5ðsV—bï9B_CHAR(0x14)__CHAR(0x19)_tñª_CHAR(0x02)_Ï2@zµàÃ,»Ýîú¨¦ÎñŒî:íã*Uø¶§u"

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}8.139.155

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.8

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

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_vhdqryacimorztk

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_CURRENT_USER\Software\remcos_vhdqryacimorztk
    • EXEpath = "r5ðsV—bï9B_CHAR(0x14)__CHAR(0x19)_tñª_CHAR(0x02)_Ï2@zµàÃ,»Ýîú¨¦ÎñŒî:íã*Uø¶§u"

Step 4

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.
  • %User Profile%\Application Data\remcos

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_RESCOMS.CJ. 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.

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System Root%\aspr_keys.ini


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