Ransom.Win32.SEON.B

 Modified by: Jemimah Mae Molina

 ALIASES:

W32/Seon.A!tr.ransom (FORTINET); Trojan-Ransom.FileCrypter (IKARUS)

 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, 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.

  TECHNICAL DETAILS

File Size:

64,193 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

28 Jun 2019

Payload:

Displays windows, Modifies system registry, 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:

  • %User Temp%\startb.bat
  • %User Temp%\readme.hta

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

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\GNU\
Display
windowData = {hex values}

Other Details

This Ransomware does the following:

  • It displays the following window after encryption:
  • It encrypts files which can be found in the following locations:
    • Fixed drives
    • Remote drives
  • It avoids encrypting the following files:
    • bootsect.bak
    • ntuser.ini
    • thumbs.db
    • your_files_are_encrypted.txt
    • ntldr
    • iconcache.db
    • desktop.ini
    • ntuser.dat.log
    • bootfont.bin
    • ntuser.dat
    • boot.ini
    • autorun.inf
  • It avoids encrypting files with the following extensions:
    • .mod
    • .adv
    • .dll
    • .msstyles
    • .mpa
    • .nomedia
    • .ocx
    • .cmd
    • .ps1
    • .themepack
    • .sys
    • .prf
    • .diagcfg
    • .cab
    • .ldf
    • .diagpkg
    • .icl
    • .386
    • .ico
    • .cur
    • .ics
    • .ani
    • .bat
    • .com
    • .rtp
    • .diagcab
    • .nls
    • .msc
    • .deskthemepack
    • .idx
    • .msp
    • .msu
    • .cpl
    • .bin
    • .shs
    • .wpx
    • .icns
    • .exe
    • .rom
    • .theme
    • .hlp
    • .spl
    • .fixt
    • .lnk
    • .scr
    • .drv
  • The batch file "%User Temp%\startb.bat" contains the following:
    • cmdexe /q /c "powershellExE -nop -w hidden -c $Sys64 = \"$env:SystemRoot\Sysnative\";$Sys32 = \"$env:SystemRoot\System32\";chcp 1251;IF (Test-Path \"$Sys64\vssadminexe\"){cmd /c \"$Sys64\vssadmin delete shadows /all /quiet\";cmd /c \"$Sys64\vssadmin delete shadows /all /quiet\"} ELSE {cmd /c \"$Sys32\vssadmin delete shadows /all /quiet\";cmd /c \"$Sys32\vssadmin delete shadows /all /quiet\"};$Disks = [SystemIODriveInfo]::getdrives() ^| ?{$_DriveType -eq \"Fixed\" };Disable-ComputerRestore $Disks;$LogicalDisks = (GET-WMIObject -query \"SELECT * from win32_logicaldisk where DriveType = '3'\");If ($LogicalDisks -ne $null) {foreach ($LD in $LogicalDisks) {$Disk = $LDDeviceID;Foreach ($LogicalDisk in $LogicalDisks) {$PrevVerEnable = \"vssadminexe Resize ShadowStorage /For=$Disk /On=$Disk /MaxSize=401MB\";$PrevVerEnableUn = \"vssadminexe Resize ShadowStorage /For=$Disk /On=$Disk /MaxSize=unbounded\";IF (Test-Path \"$Sys64\vssadminexe\") {cmd /c \"$Sys64\$PrevVerEnable\";cmd /c \"$Sys64\$PrevVerEnableUn\"} ELSE {cmd /c \"$Sys32\$PrevVerEnable\";cmd /c \"$Sys32\$PrevVerEnableUn\"}}}};IF (Test-Path \"$Sys64\vssadminexe\") {cmd /c \"$Sys64\bcdedit /set {default} recoveryenabled No\";cmd /c \"$Sys64\bcdedit /set {default} bootstatuspolicy ignoreallfailures\";cmd /c \"$Sys64\vssadmin delete shadows /all /quiet\"} ELSE {cmd /c \"$Sys32\bcdedit /set {default} recoveryenabled No\";cmd /c \"$Sys32\bcdedit /set {default} bootstatuspolicy ignoreallfailures\";cmd /c \"$Sys32\vssadmin delete shadows /all /quiet\"}"

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • system volume information
  • programdata
  • application data
  • $windows.~bt
  • program files
  • tor browser
  • windows
  • mozilla
  • appdata
  • windows.old
  • program files (x86)
  • $recycle bin
  • google
  • boot

It renames encrypted files using the following names:

  • {file name}.{file extension}.FIXT

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

  • {Encrypted Directory}\YOUR_FILES_ARE_ENCRYPTED.TXT

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.208.04

FIRST VSAPI PATTERN DATE:

01 Jul 2019

VSAPI OPR PATTERN File:

15.209.00

VSAPI OPR PATTERN Date:

02 Jul 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\GNU\Display
    • windowData = {hex values}

Step 4

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.
  • %User Temp%\startb.bat
  • %User Temp%\readme.hta
  • {Encrypted Directory}\YOUR_FILES_ARE_ENCRYPTED.TXT

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.SEON.B. 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 6

Restore encrypted files from backup.


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