Analysis by: Jay Bradley Nebre
ALIASES:

a variant of Win32/Filecoder.RobbinHood.A trojan(NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

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.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 2,855,424 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 May 2019
Payload: Displays windows, Displays message/message, Encrypts 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 files:

  • %Temp%\rf_l - contains logs of encrypted files
  • %Temp%\rf_s - contains logs of encrypted files
  • %Temp%\ro_l - contains logs of encrypted files
  • %Temp%\ro_s - contains logs of encrypted files

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

It adds the following processes:

  • cmd.exe /c sc.exe stop KAVFS - disable service
  • cmd.exe /c sc.exe stop RESvc - disable service
  • cmd.exe /c sc.exe stop SamSs - disable service
  • cmd.exe /c sc.exe stop W3Svc - disable service
  • cmd.exe /c sc.exe stop bedbg - disable service
  • cmd.exe /c sc.exe stop masvc - disable service
  • cmd.exe /c net use * /DELETE /Y - to disbale all network connections

Other Details

This Ransomware requires the following additional components to properly run:

  • %Temp%\pub.key - contains a public key that the malware use to encrypt files

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

It displays a pop-up window with the following message:

If it cant locate pub.key

After finishing the encryption routine

Ransomware Routine

This Ransomware renames encrypted files using the following names:

  • Encrypted_{randomstring}.enc_robbinhood

It drops the following file(s) as ransom note:

    • _Decrypt_files.html
    • _Decryption_ReadMe.html
    • _Help_Help_Help.html
    • _Help_Important.html



  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.986.05
FIRST VSAPI PATTERN DATE: 08 May 2019
VSAPI OPR PATTERN File: 14.987.00
VSAPI OPR PATTERN Date: 09 May 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

Identify and terminate files detected as Ransom.Win32.ROBBINHOOD.A

[ 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 3

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.
  • %Temp%\pub.key
  • %Temp%\rf_l
  • %Temp%\rf_s
  • %Temp%\ro_l
  • %Temp%\rp_s
  • _Decrypt_files.html
  • _Decryption_ReadMe.html
  • _Help_Help_Help.html
  • _Help_Important.html

Step 4

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

Step 5

Restore encrypted files from backup.


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