RANSOM_BTCWARE.AO

February 06, 2018
 Analysis by: Michael Jhon Ofiaza
 ALIASES:

Trojan Horse (Norton) , Troj/Btcware-A (Sophos Lite) , Ransom:Win32/Betisrypt.D [non_writable_container] (Microsoft)

 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:

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 is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

272,648 bytes

File Type:

Other

Memory Resident:

No

Initial Samples Received Date:

28 Nov 2017

Payload:

Encrypts files, Displays message/message boxes

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:

    Other System Modifications

    This Ransomware adds the following registry entries:

    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 displays the following images:

    It does the following:

    • It executes the following commands:
      • vssadmin.exe delete shadows /all /quiet
      • bcdedit.exe /set {default} recoveryenabled No
      • bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures

    It is capable of encrypting files in the affected system.

    Ransomware Routine

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

    • Payday.hta
    • !! RETURN FILES !!.txt
    • BOOTMGR
    • .payday
    • payload.exe

    It avoids encrypting files found in the following folders:

    • $recycle.bin
    • msocache
    • windows
    • Temp

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

    • .[gh0stcrypt@{BLOCKED}a.io or whitedevil@{BLOCKED}ta.de]-id-{process id in Hex}.payday

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

    • %Application Data%\payday.hta
    • {Drive Letter}:\!! RETURN FILES !!.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.)

    It leaves text files that serve as ransom notes containing the following text:

    • all your files have been encrypted want return files? write on email: gh0stcrypt@{BLOCKED}a.io or whitedevil@{BLOCKED}ta.de

      SOLUTION

    Minimum Scan Engine:

    9.850

    FIRST VSAPI PATTERN FILE:

    13.810.08

    FIRST VSAPI PATTERN DATE:

    28 Nov 2017

    VSAPI OPR PATTERN File:

    13.811.00

    VSAPI OPR PATTERN Date:

    29 Nov 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 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}:\!! RETURN FILES !!.txt

    Step 6

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