Analysis by: Wilbert Vidal
ALIASES:

Backdoor:Win32/Fynloski!rfn (Microsoft); BackDoor.Comet.884 (DrWeb)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

This Ransomware 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: 1,381,888 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Jun 2017
Payload: Displays graphics/image, Drops files

Arrival Details

This Ransomware 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 Ransomware drops the following component file(s):

  • C:\Temp\win32.sys

It drops and executes the following files:

  • C:\Users\Johannes\Desktop\Temp.exe
  • C:\Temp\Copier.exe - Runs when "Copy Button" was clicked
  • C:\Temp\Payer.exe - Runs when "Check Button" was clicked
  • %Windows%\win64.exe - Runs when "Pay Button" was clicked <-- Delete Afterwards
    • Drops %System%\MSDCSC\msdcsc.exe - Detected as BKDR_FLYNLOS.SMM

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • taskmgr.exe

Other Details

This Ransomware does the following:

  • It hides the task bar

NOTES:
It displays the following window applications as ransom note:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.468.01
FIRST VSAPI PATTERN DATE: 12 Jun 2017
VSAPI OPR PATTERN File: 13.469.00
VSAPI OPR PATTERN Date: 13 Jun 2017

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

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

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.  
  • C:\Users\Johannes\Desktop\Temp.exe
  • C:\Temp\Copier.exe
  • C:\Temp\Payer.exe

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CASHOUT.A. 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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