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RANSOM_BTCWARE.AS

February 10, 2018
 Analysis by: Camille Reyes
 ALIASES:

Ransom:Win32/Betisrypt.D (MICROSOFT); Gen:Variant.Ransom.BTCWare.35 (BITDEFENDER)

 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.

It is capable of encrypting files in the affected system.

It encrypts files found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

274,432 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

23 Jan 2018

Payload:

Displays message/message boxes, 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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • PAYDAYDAYPAY

Other System Modifications

This Ransomware adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
1payday = %Application Data%\payday.hta

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
2baby = %Application Data%\payday.hta

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
3payday = %Application Data%\payday.hta

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
4baby = %Application Data%\payday.hta

Other Details

This Ransomware is capable of encrypting files in the affected system.

It executes the following command to disable/stop/delete Windows components:

  • cmd.exe /c vssadmin.exe Delete Shadows /All /Quiet
  • cmd.exe /c bcdedit.exe /set {default} recoveryenabled No
  • cmd.exe /c bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • {Drive Letter}:\

It avoids encrypting files with the following strings in their file name:

  • payday.hta
  • ! FILES ENCRYPTED.txt
  • BOOTMGR
  • .wallet
  • wallet
  • {Malware Name}.exe

It avoids encrypting files with the following strings in their file path:

  • Windows
  • intel
  • nvidia

It appends the following extension to the file name of the encrypted files:

  • [arkana@{BLOCKED}a.io]-id-{Hex Value of Malware PID}.wallet

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

  • %Application Data%\payday.hta
  • {Drive Letter}:\! FILES ENCRYPTED.txt

NOTES:

This ransomware displays the following as its ransom note:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.934.01

FIRST VSAPI PATTERN DATE:

28 Jan 2018

VSAPI OPR PATTERN File:

13.935.00

VSAPI OPR PATTERN Date:

29 Jan 2018

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

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
    • 1payday = %Application Data%\payday.hta
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 2baby = %Application Data%\payday.hta
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 3payday = %Application Data%\payday.hta
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 4baby = %Application Data%\payday.hta

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.
  • %Application Data%\payday.hta
  • {Drive Letter}:\! FILES ENCRYPTED.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_BTCWARE.AS. 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 7

Restore encrypted files from backup.


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