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Ransom.Win32.PHOBOS.AI

June 17, 2019
 Analysis by: Jay Garcia
 ALIASES:

Trojan-Ransom.Phobos(Ikarus); Trojan-Ransom.Win32.Blocker.masy(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, 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:

71,168 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Jun 2019

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 processes:

  • netsh advfirewall set currentprofile state off
  • vssadmin delete shadows /all /quiet -> delete shadow copies
  • wmic shadowcopy delete -> delete shadow copies
  • bcdedit /set {default} bootstatuspolicy ignoreallfailures -> disable system's trigger to call the Error Recovery screen on startup
  • cmd.exe /C Bcdedit.exe /set {default} recoveryenabled no -> Disables Windows Recovery on Startup
  • netsh firewall set opmode mode=disable
  • "%System%\mshta.exe" "{Drive letter}\info.hta" -> Executes dropped ransom note
  • "%System%\mshta.exe" "%Desktop%\info.hta" -> Executes dropped ransom note
  • "%System%\mshta.exe" "%Public%\desktop\info.hta" -> Executes dropped ransom note

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %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).. %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\0001{ID-Volume Serial Number}

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware File Name} = "%AppDataLocal%\{malware file name}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Malware File Name} = "%AppDataLocal%\{malware file name}.exe"

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Enable = 1

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Size = 10

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
InitHits = 100

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Factor = 20

Dropping Routine

This Ransomware drops the following files:

  • %AppDataLocal%\{Malware File Name}.exe
  • %Common Startup%\{Malware File Name}.exe

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Ransomware does the following:

  • It avoids to encrypt the following files:
    • boot.ini
    • bootfont.bin
    • ntldr
    • ntdetect.com
    • io.sys

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • %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:

  • {File Name}.{File Extension}.id[ID-Volume Serial Number].[datadecrypt@{BLOCKED}q.com].actin

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

  • {Drive Letter}\info.hta
  • %Desktop%\info.hta
  • %Public%\desktop\info.hta
  • %Desktop%\info.hta
  • %Public%\desktop\info.txt
  • {Drive Letter}\info.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.174.05

FIRST VSAPI PATTERN DATE:

14 Jun 2019

VSAPI OPR PATTERN File:

15.175.00

VSAPI OPR PATTERN Date:

15 Jun 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

Restart in Safe Mode

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Malware File Name} = "%AppDataLocal%\{malware file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware File Name} = "%AppDataLocal%\{malware file name}.exe"

Step 4

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\Microsoft\Internet Explorer\International\CpMRU
    • Enable = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
    • Size = 10
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
    • InitHits = 100
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
    • Factor = 20

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. =
  • %AppDataLocal%\{Malware File Name}.exe
  • %Common Startup%\{Malware File Name}.exe
  • {Drive Letter}\info.txt
  • %Desktop%\info.hta
  • %Public%\desktop\info.hta

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.PHOBOS.AI. 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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