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Ransom.Win32.NETWALKER.SBA

April 15, 2020
 Analysis by: Joshua John Bantayan
 ALIASES:

Trojan-Ransom.NetWalker (IKARUS); Ransom:Win32/NetWalker.S!MTB (MICROSOFT)

 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:

Dropped by other malware, 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. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

70,656 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

14 Apr 2020

Payload:

Terminates processes, 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 files:

  • %User Temp%\{4 random characters}.tmp.bat -> terminates malware process and deletes malware file and itself

(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).)

It adds the following processes:

  • %System%\vssadmin.exe delete shadows /all /quiet
  • %System%\notepad.exe "%Desktop%\{6 random characters}-Readme.txt"
  • cmd /c "%User Temp%\{4 random characters}.tmp.bat

(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).. %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).)

It executes then deletes itself afterward.

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{8 random characters}
{8 random characters} = {Hex values}

HKEY_CURRENT_USER\Software\{8 random characters}
{8 random characters} = {Hex values}

Process Termination

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

  • Lotus*
  • veeam*
  • cbvscserv*
  • hMailServer
  • backup*
  • *backup*
  • apach*
  • firebird*
  • ibmiasrw
  • IBM Domino*
  • Simply Accounting Database Connection Manager
  • IASJet
  • QB*
  • *sql*
  • sql*
  • QuickBooksDB*
  • IISADMIN
  • omsad
  • dc*32
  • server Administrator
  • wbengine
  • mr2kserv
  • MSExchange*
  • ShadowProtectSvc
  • SP*4
  • teamviewer
  • MMS
  • AcronisAgent
  • ARSM
  • AcrSch2Svc
  • vsnapvss
  • SPXService
  • StorageCraft ImageManager
  • wrsvc
  • stc_endpt_svc
  • acrsch2svc*

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 does the following:

  • It encrypts all available drives including network drives as well as network resources.
  • It impersonates the winlogon.exe account token.
  • It checks the Task name, arguments and task to run of the scheduled tasks and deletes them if the following strings are found:
    • reboot
    • restart
    • shutdown
    • logoff
    • back

Ransomware Routine

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

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

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

  • *system volume information
  • *windows.old
  • *:\users\*\*temp
  • *msocache
  • *:\winnt
  • *$windows.~ws
  • *perflogs
  • *boot
  • *:\windows
  • *:\program file*\vmware
  • \*\users\*\*temp
  • \*\winnt
  • \*\windows
  • *\program file*\vmware
  • *appdata*microsoft
  • *appdata*packages
  • *microsoft\provisioning
  • *dvd maker
  • *Internet Explorer
  • *Mozilla
  • *Mozilla*
  • *Old Firefox data
  • *\program file*\windows media*
  • *\program file*\windows portable*
  • *windows defender
  • *\program file*\windows nt
  • *\program file*\windows photo*
  • *\program file*\windows side*
  • *\program file*\windowspowershell
  • *\program file*\cuass*
  • *\program file*\microsoft games
  • *\program file*\common files\system
  • *\program file*\common files\*shared
  • *\program file*\common files\reference ass*
  • *\windows\cache*
  • *temporary internet*
  • *media player
  • *:\users\*\appdata\*\microsoft
  • \*\users\*\appdata\*\microsoft
  • *\Program File*\Cisco

It renames encrypted files using the following names:

  • {Encrypted file}.{6 random characters}

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

  • {Encrypted directory}\{6 random characters}-Readme.txt

It avoids encrypting files with the following file extensions:

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.806.02

FIRST VSAPI PATTERN DATE:

15 Apr 2020

VSAPI OPR PATTERN File:

15.807.00

VSAPI OPR PATTERN Date:

16 Apr 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\{8 random characters}
    • {8 random characters} = {Hex values}
  • In HKEY_CURRENT_USER\Software\{8 random characters}
    • {8 random characters} = {Hex values}

Step 6

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}
  • In HKEY_CURRENT_USER\Software
    • {8 random characters}

Step 7

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