RANSOM_BITCOVAR.A

March 07, 2018
 Analysis by: Noel Anthony Llimos
 ALIASES:

Trojan-Ransom.Win32.Bitcovar.gj (Kaspersky), Ransom:Win32/Betisrypt.D (Microsoft), Gen:Variant.Razy.224118 (Bitdefender)

 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:

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:

358,400 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Dec 2017

Payload:

Drops files, 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:

  • PAYDAYPAYDAY

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

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

It drops the following files:

  • %Application Data%\paydata.hta
  • {Drive}\! FILES ENCRYPTED.txt

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

This Ransomware encrypts files with the following extensions:

  • .pps
  • .pdf
  • .pot
  • .xlt
  • .pps
  • .xlw
  • .dot
  • .rtf
  • .ppt
  • .pptx
  • .xls
  • .xlsx
  • .xlw
  • .doc
  • .docx
  • .xml
  • .hta
  • .htm
  • .html
  • .jpg
  • .jpeg
  • .gif
  • .png
  • .tif
  • .tiff
  • .bmp
  • .ico
  • .wmf
  • .dib
  • .jfif
  • .jpe
  • .fpx
  • .mix
  • .dot
  • .xbap
  • .exe
  • .search-ms
  • .mht
  • .zip
  • .dvr-ms
  • .wvx
  • .wmx
  • .wmv
  • .wm
  • .mpv2
  • .mpg
  • .mpeg
  • .mpe
  • .mpa
  • .mp2v
  • .mp2
  • .m1v
  • .IVF
  • .asx
  • .asf
  • .wax
  • .snd
  • .rmi
  • .m3u
  • .au
  • .aiff
  • .aifc
  • .aif
  • .midi
  • .mid
  • .wma
  • .wav
  • .mp3
  • .wmf
  • .tiff
  • .tif
  • .rle
  • .png
  • .jpeg
  • .jpe
  • .jpg
  • .jfif
  • .ico
  • .gif
  • .emf
  • .dib
  • .bmp

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


It does the following:

  • It encrypts all files in fixed and network drives.
  • It deletes shadow copies by executing the following command:
    • /C vssadmin Delete Shadows /All /Quiet
    • /C wmic shadowcopy delete
    • /C Bcdedit.exe /set {default} recoveryenabled no
    • /C Bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .[{BLOCKED}supp@{BLOCKED}l.cc or {BLOCKED}VHx6b7RYhJ9gGKZn6yTuBpBBq3LHRkz@{BLOCKED}sage.ch ]-id-260.wallet

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.824.06

FIRST VSAPI PATTERN DATE:

04 Dec 2017

VSAPI OPR PATTERN File:

13.825.00

VSAPI OPR PATTERN Date:

05 Dec 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

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 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.  
  • %Application Data%\paydata.hta
  • {Drive}\! FILES ENCRYPTED.txt

Step 6

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

Step 7

Restore encrypted files from backup.

Step 8

Scan your computer with your Trend Micro product to delete files detected as RANSOM_BITCOVAR.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:


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