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Ransom.Win32.MAILTO.ADC

January 31, 2020
 Analysis by: Arianne Grace Dela Cruz
 ALIASES:

Trojan:Win32/Nemty.PD!MTB(MICROSOFT); Trojan-Ransom.Win32.Mailto.a (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 deletes itself after execution.

It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Jan 2020

Payload:

Disables services, Terminates processes, 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 drops the following copies of itself into the affected system:

  • %Program Files%\{8 random characters}\{8 random characters}.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • %System%\vssadmin.exe delete shadows /all /quiet
  • %System%\explorer.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %Program Files%\{8 random characters}

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

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
{8 random characters} = "%Program Files%\{8 random characters}\{8 random characters}.exe"

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{8 random characters}
{8 random characters} = "{hex values}"

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • Lotus
  • cbvscserv
  • hMailServer
  • backup
  • backup
  • apach
  • firebird
  • ibmiasrw
  • IBM Domino
  • Simply Accounting Database Connection Manager
  • IASJet
  • QB
  • sql
  • sql
  • QuickBooksDB
  • IISADMIN
  • omsad
  • dc32
  • server Administrator
  • wbengine
  • mr2kserv
  • MSExchange
  • ShadowProtectSvc
  • SP4
  • teamviewer
  • MMS
  • AcronisAgent
  • ARSM
  • AcrSch2Svc
  • vsnapvss
  • SPXService
  • StorageCraft ImageManager
  • wrsvc
  • stc_endpt_svc
  • acrsch2svc
  • veaam

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

  • nslsvice.exe
  • pg
  • nservice.exe
  • cbvscserv
  • ntrtscan.exe
  • cbservi
  • hMailServer
  • IBM
  • bes10
  • black
  • apach
  • bd2
  • db
  • ba
  • be
  • QB
  • oracle
  • wbengine
  • vee
  • postg
  • sage
  • sap
  • b1
  • fdlaunch
  • msmdsrv
  • report
  • msdtssr
  • coldfus
  • cfdot
  • swag
  • swstrtr
  • jetty.exe
  • wrsa.exe
  • team
  • agent
  • store.exe
  • sql
  • sqbcoreservice.exe
  • thunderbird.exe
  • ocssd.exe
  • encsvc.exe
  • excel.exe
  • synctime.exe
  • mspub.exe
  • ocautoupds.exe
  • thebat.exe
  • dbeng50.exe
  • sql
  • mydesktopservice.exe
  • onenote.exe
  • outlook.exe
  • powerpnt.exe
  • msaccess.exe
  • tbirdconfig.exe
  • wordpad.exe
  • ocomm.exe
  • dbsnmp.exe
  • thebat64.exe
  • winword.exe
  • oracle.exe
  • xfssvccon.exe
  • firefoxconfig.exe
  • visio.exe
  • mydesktopqos.exe
  • infopath.exe
  • agntsvc.exe

Other Details

This Ransomware deletes itself after execution.

Ransomware Routine

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

  • autorun.inf
  • boot.ini
  • bootfont.bin
  • bootmgr
  • bootnxt
  • bootsect.bak
  • desktop.ini
  • gdipfont.dat
  • iconcache.db
  • ntldr
  • ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db

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

  • system volume information
  • windows.old
  • userstemp
  • msocache
  • winnt
  • $windows.~ws
  • perflogs
  • boot
  • windows
  • program filevmware
  • userstemp
  • winnt
  • windows
  • program filevmware
  • appdatamicrosoft
  • appdatapackages
  • microsoftprovisioning
  • dvd maker
  • Internet Explorer
  • Mozilla
  • Mozilla
  • Old Firefox data
  • program filewindows media
  • program filewindows portable
  • windows defender
  • program filewindows nt
  • program filewindows photo
  • program filewindows side
  • program filewindowspowershell
  • program filecuass
  • program filemicrosoft games
  • program filecommon filessystem
  • program filecommon filesshared
  • program filecommon filesreference ass
  • windowscache
  • temporary internet
  • media player

It renames encrypted files using the following names:

  • {encrypted file}.mailto[2Hamlampampom@{BLOCKED}k.li].{5 random characters}

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

  • {Encrypted Directory}\{5 Random Characters}-Readme.txt

It avoids encrypting files with the following file extensions:

  • 386
  • adv
  • ani
  • cab
  • clb
  • cmd
  • com
  • cpl
  • cur
  • deskthemepack
  • diagcab
  • diagcfg
  • diagpkg
  • dll
  • drv
  • exe
  • hlp
  • hta
  • icl
  • icns
  • ico
  • ics
  • idx
  • key
  • ldf
  • lnk
  • lock
  • mo
  • mpa
  • msc
  • msi
  • msp
  • msstyles
  • msu
  • mui
  • nls
  • nomedia
  • ocx
  • prf
  • ps1
  • regtrans-ms
  • rom
  • rtp
  • scr
  • shs
  • spl
  • sys
  • theme
  • themepack
  • wpx

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.654.03

FIRST VSAPI PATTERN DATE:

31 Jan 2020

VSAPI OPR PATTERN File:

15.655.00

VSAPI OPR PATTERN Date:

01 Feb 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 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_LOCAL_MACHINE\software
    • {8 random characters}

Step 6

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
    • {8 random characters}= %Program Files%\{8 random characters}\{8 random characters}.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\c78dd81c87
    • {8 random characters} = {random characters}

Step 7

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Program Files%\{8 random characters}

Step 8

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}\{5 Random Characters}-Readme.txt

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.MAILTO.ADC. 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 10

Restore encrypted files from backup.


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