Ransom.Win32.BURAN.WGL

 Analysis by: Wilbert Luy

 ALIASES:

HEUR:Trojan.Win32.BuhTrap.gen (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

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 executes then deletes itself afterward.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

170,496 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

21 Aug 2019

Payload:

Connects to URLs/IPs, 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 drops the following copies of itself into the affected system:

  • %Application Data%\Microsoft\Windows\lsass.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • %System%\cmd.exe" /e:on /c md "%Applicatyion Data%\Microsoft\Windows" & copy "%Desktop%\{Malware Name}.exe" "%Application Data%\Microsoft\Windows\lsass.exe" & reg add "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /V "Local Security Authority Subsystem Service" /t REG_SZ /F /D "\"%Application Data%\Microsoft\Windows\lsass.exe\" *"
  • reg add "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /V "Local Security Authority Subsystem Service" /t REG_SZ /F /D "\"%Application Data%\Microsoft\Windows\lsass.exe\" *"
  • "%Application Data%\Microsoft\Windows\lsass.exe" *
  • ping -n 3 127.1
  • "%System%\cmd.exe" /C bcdedit /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit /set {default} bootstatuspolicy ignoreallfailures
  • "%System%\cmd.exe" /C bcdedit /set {default} recoveryenabled no
  • bcdedit /set {default} recoveryenabled no
  • "%System%\cmd.exe" /C wbadmin delete catalog -quiet
  • wbadmin delete catalog -quiet
  • "%System%\cmd.exe" /C wbadmin delete systemstatebackup
  • wbadmin delete systemstatebackup
  • "%System%\cmd.exe" /C wbadmin delete systemstatebackup -keepversions:0
  • wbadmin delete systemstatebackup -keepversions:0
  • "%System%\cmd.exe" /C wbadmin delete backup
  • wbadmin delete backup
  • "%System%\cmd.exe" /C wmic shadowcopy delete
  • wmic shadowcopy delete
  • "%System%\cmd.exe" /C vssadmin delete shadows /all /quiet
  • vssadmin delete shadows /all /quiet
  • "%System%\cmd.exe" /C reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default" /va /f
  • reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default" /va /f
  • /C reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers" /f
  • reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers" /f
  • /C reg add "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers"
  • reg add "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers"
  • "%System%\cmd.exe" /C attrib "%userprofile%\documents\Default.rdp" -s -h
  • attrib "%User Profile%\documents\Default.rdp" -s -h
  • "%System%\cmd.exe" /C del "%userprofile%\documents\Default.rdp"
  • "%System%\cmd.exe" /C wevtutil.exe clear-log Application
  • wevtutil.exe clear-log Application
  • "%System%\cmd.exe" /C wevtutil.exe clear-log Security
  • wevtutil.exe clear-log Security
  • "%System%\cmd.exe" /C wevtutil.exe clear-log System
  • wevtutil.exe clear-log System
  • "%System%\cmd.exe" /C sc config eventlog start=disabled
  • sc config eventlog start=disabled
  • "%System%\notepad.exe" %Desktop%\!!! YOUR FILES ARE ENCRYPTED !!!.TXT
  • "%System%\cmd.exe" /c for /l %x in (1,1,999) do ( ping -n 3 127.1 & del "%Desktop%\buran.exe" & if not exist "%Desktop%\buran.exe" exit )
  • "%System%\cmd.exe" /c for /l %x in (1,1,999) do ( ping -n 3 127.1 & del "%Application Data%\Microsoft\Windows\lsass.exe" & if not exist %Application Data%\Microsoft\Windows\lsass.exe" exit )

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It executes then deletes itself afterward.

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

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
Local Security Authority Subsystem Service = ""%Application Data%\Microsoft\Windows\lsass.exe" *"

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Buran III

HKEY_CURRENT_USER\Software\Buran III\
Service

HKEY_LOCAL_MACHINE\BCD00000000\Objects\
{GUID}\Elements\250000e0

HKEY_CURRENT_USER\Software\Microsoft\
Terminal Server Client

HKEY_CURRENT_USER\Software\Microsoft\
Terminal Server Client\Servers

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Buran III
Knock = "666"

HKEY_CURRENT_USER\Software\Buran III\
Service
Public Key = ""

HKEY_CURRENT_USER\Software\Buran III\
Service
Machine ID = ""

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosX = "164"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosY = "100"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosDX = "716"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosDY = "638"

Other Details

This Ransomware connects to the following URL(s) to get the affected system's IP address:

  • geoiptool.com
  • iplogger.ru
  • iplogger.org

It does the following:

  • It avoids encrypting files with the following file extension:
    • .cmd
    • .com
    • .cpl
    • .dll
    • .msc
    • .msp
    • .pif
    • .scr
    • .sys
    • .log
    • .exe
    • .lnk
    • .buran
  • It also encrypts files in shared folders.

Ransomware Routine

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

  • bootfont.bin
  • bootsect.bak
  • desktop.ini
  • ctfmon.exe
  • iconcache.db
  • master.exe
  • master.dat
  • ntdetect.com
  • ntldr
  • ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db
  • !!! your files are encrypted !!!.txt

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

  • :\$recycle.bin\
  • :\$windows.~bt\
  • :\recycler
  • :\system volume information\
  • :\windows.old
  • :\windows\
  • :\intel\
  • :\nvidia\
  • :\inetpub\logs\
  • \appdata\
  • \apple computer\safari\
  • \application data\
  • \boot\
  • \google\
  • \google\chrome\
  • \mozilla firefox\
  • \mozilla\
  • \opera software\
  • \opera\
  • \tor browser\
  • \common files\
  • \internet explorer\
  • \windows defender\
  • \windows mail\
  • \windows media player\
  • \windows multimedia platform\
  • \windows nt\
  • \windows photo viewer\
  • \windows portable devices\
  • \windowspoershell\
  • \windows security\
  • \embedded lockdown manager\
  • \windows journal\
  • \msbuild\
  • \reference assemblies\
  • \windows sidebar\
  • \windows defender advanced threat protection\
  • \microsoft\
  • \package cache\
  • \microsoft help\
  • \desktop\
  • %Windows%

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

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

  • .{GUID}

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

  • {Encrypted Directory}:\!!! YOUR FILES ARE ENCRYPTED !!!.TXT
  • %Desktop%\:\!!! YOUR FILES ARE ENCRYPTED !!!.TXT

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.332.01

FIRST VSAPI PATTERN DATE:

29 Aug 2019

VSAPI OPR PATTERN File:

15.333.00

VSAPI OPR PATTERN Date:

30 Aug 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

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

Delete this registry key

[ 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
    • Buran III
  • In HKEY_CURRENT_USER\Software\Buran III
    • Service
  • In HKEY_LOCAL_MACHINE\BCD00000000\Objects\{GUID}\Elements
    • 250000e0
  • In HKEY_CURRENT_USER\Software\Microsoft
    • Terminal Server Client
  • In HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client
    • Servers

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
    • Local Security Authority Subsystem Service = ""%Application Data%\Microsoft\Windows\lsass.exe" *"
  • In HKEY_CURRENT_USER\Software\Buran III
    • Knock = "666"
  • In HKEY_CURRENT_USER\Software\Buran III\Service
    • Public Key = ""
  • In HKEY_CURRENT_USER\Software\Buran III\Service
    • Machine ID = ""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • iWindowPosX = "164"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • iWindowPosY = "100"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • iWindowPosDX = "716"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • iWindowPosDY = "638"

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.
  • {Encrypted Directory}:\!!! YOUR FILES ARE ENCRYPTED !!!.TXT
  • %Desktop%\:\!!! YOUR FILES ARE ENCRYPTED !!!.TXT

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.BURAN.WGL. 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 7

Restore encrypted files from backup.


Did this description help? Tell us how we did.