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Ransom.Win32.PHOBOS.FMKST

March 03, 2020
 Analysis by: Earle Maui Earnshaw
 ALIASES:

HEUR:Trojan.Win32.Generic (Kaspersky); Trojan:Win32/Phoenix (Microsoft)

 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:

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 encrypts files found in specific folders. It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

52,224 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

02 Mar 2020

Payload:

Encrypts files, Displays message/message boxes, Terminates processes

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:

  • %AppDataLocal%\{Malware Filename}.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).)

It adds the following processes:

  • netsh advfirewall set currentprofile state off
  • netsh firewall set opmode mode=disable
  • "%System%\mshta.exe" "%Desktop%\info.hta"
  • "%System%\mshta.exe" "%Public%\Desktop\info.hta"

(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).. %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\<<BID>>{Generated ID}00000001
  • Global\<<BID>>{Generated ID}00000000

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 Filename} = %AppDataLocal%\{Malware Filename}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = %AppDataLocal%\{Malware Filename}.exe

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\{Malware Filename}.exe → Will drop if malware is executed as non-admin

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

It drops the following file(s) in the Windows Common Startup folder to enable its automatic execution at every system startup:

  • %Common Startup%\{Malware Filename}.exe

(Note: %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.)

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • agntsvc.exe
  • dbeng50.exe
  • dbsnmp.exe
  • encsvc.exe
  • excel.exe
  • firefoxconfig.exe
  • infopath.exe
  • isqlplussvc.exe
  • msaccess.exe
  • msftesql.exe
  • mspub.exe
  • mydesktopqos.exe
  • mydesktopservice.exe
  • mysqld.exe
  • mysqld-nt.exe
  • mysqld-opt.exe
  • ocautoupds.exe
  • ocomm.exe
  • ocssd.exe
  • onenote.exe
  • oracle.exe
  • outlook.exe
  • powerpnt.exe
  • sqbcoreservice.exe
  • sqlagent.exe
  • sqlbrowser.exe
  • sqlservr.exe
  • sqlwriter.exe
  • steam.exe
  • synctime.exe
  • tbirdconfig.exe
  • thebat.exe
  • thebat64.exe
  • thunderbird.exe
  • visio.exe
  • winword.exe
  • wordpad.exe
  • xfssvccon.exe

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %Windows%
  • %All Users Profile%\microsoft\windows\caches
  • %System Root%\Users\admin\microsoft\windows\caches

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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

  • Filename:
    • info.hta
    • info.txt
    • boot.ini
    • bootfont.bin
    • ntldr
    • ntdetect.com
    • io.sys
    • {malware Filename}.exe

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

  • {Filename with extension}.id[{Generated ID}-{Volume Serial Number}.[crazyfrog1233@{BLOCKED}om].Dever

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

  • %Desktop%\info.hta
  • %Public%\Desktop\info.hta
  • %Desktop%\info.txt
  • %Public%\Desktop\info.txt

It avoids encrypting files with the following file extensions:

  • fdb
  • sql
  • 4dd
  • 4dl
  • abs
  • abx
  • accdb
  • accdc
  • accde
  • adb
  • adf
  • ckp
  • db
  • db-journal
  • db-shm
  • db-wal
  • db2
  • db3
  • dbc
  • dbf
  • dbs
  • dbt
  • dbv
  • dcb
  • dp1
  • eco
  • edb
  • epim
  • fcd
  • gdb
  • mdb
  • mdf
  • ldf
  • myd
  • ndf
  • nwdb
  • nyf
  • sqlitedb
  • sqlite3
  • sqlite
  • dever
  • actin
  • acton
  • actor
  • acuff
  • acuna
  • acute
  • adage
  • adair
  • adame
  • banhu
  • banjo
  • banks
  • banta
  • barak
  • caleb
  • cales
  • caley
  • calix
  • calle
  • calum
  • calvo
  • deuce
  • dever
  • devil
  • devoe
  • devon
  • devos
  • dewar
  • eight
  • eject
  • eking
  • elbie
  • elbow
  • elder
  • phobos
  • help
  • blend
  • bqux
  • com
  • mamba
  • karlos
  • ddos
  • phoenix
  • plut
  • karma
  • bbc
  • capital
  • wallet

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.718.08

FIRST VSAPI PATTERN DATE:

02 Mar 2020

VSAPI OPR PATTERN File:

15.719.00

VSAPI OPR PATTERN Date:

03 Mar 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     Troj.Win32.TRX.XXPE50FFF034

Step 2

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 3

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

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 Filename} = %AppDataLocal%\{Malware Filename}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = C:\Users\dyituser_732\AppData\Local\{Malware Filename}.exe

Step 6

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.
  • %Public%\Desktop\info.txt
  • %Public%\Desktop\info.hta
  • %Desktop%\info.txt
  • %Desktop%\info.hta
  • %User Startup%\{Malware File Name}.exe
  • %Common Startup%\{Malware File Name}.exe
  • %AppDataLocal%\{Malware File Name}.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.PHOBOS.FMKST. 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 8

Restore encrypted files from backup.


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