Analysis by: Bren Matthew Ebriega
 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. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 1,241,326 bytes
File Type: PS1
Memory Resident: Yes
Initial Samples Received Date: 24 Jan 2021
Payload: Displays graphics/image, Encrypts files, Injects code

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%\CSC{Random Characters}.tmp
  • %User Temp%\RES{Random Characters}.tmp
  • %User Temp%\{Random Characters}.0.cs
  • %User Temp%\{Random Characters}.dll
  • %User Temp%\{Random Characters}.cmdline
  • %User Temp%\{Random Characters}.out
  • %User Temp%\{Random Characters}.err
  • %User Temp%\{Random Characters}.pdb

(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:

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\csc.exe /noconfig /fullpaths @"%User Temp%\{Random Characters}.cmdline"
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\cvtres.exe /NOLOGO /READONLY /MACHINE:IX86 "/OUT:%User Temp%\RES{Random Characters}.tmp" "%User Temp%\CSC{Random Characters}.tmp"
  • %System%\notepad.exe %Desktop%\{Appended Extension}-Readme.txt

(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).. %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).)

It injects codes into the following process(es):

  • explorer.exe

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 would determine if the system it is running on is 64-bit or 32-bit and will use the architecture appropriate payload based on the result of its checking.

It deletes the following files to remove its traces in the system:

  • %User Temp%\CSC{Random Characters}.tmp
  • %User Temp%\RES{Random Characters}.tmp
  • %User Temp%\{Random Characters}.0.cs
  • %User Temp%\{Random Characters}.dll
  • %User Temp%\{Random Characters}.cmdline
  • %User Temp%\{Random Characters}.out
  • %User Temp%\{Random Characters}.err
  • %User Temp%\{Random Characters}.pdb

(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).)

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*
  • ntuser.ini
  • thumbs.db
  • usrclass.dat
  • usrclass.dat*

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:

  • {Original Filename}.{Original extension}.{6 Random Characters}

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

  • %Desktop%\{Appended Extension}-Readme.txt
  • {Encrypted Directory}\{Appended Extension}-Readme.txt

It avoids encrypting files with the following file extensions:

  • .386
  • .adv
  • .ani
  • .bat
  • .cab
  • .clb
  • .cmd
  • .com
  • .cpl
  • .cur
  • .deskthemepack
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .dll
  • .drv
  • .exe
  • .hlp
  • .hta
  • .icl
  • .icns
  • .ico
  • .ics
  • .idx
  • .key
  • .ldf
  • .lnk
  • .lock
  • .mod
  • .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: 9.800
FIRST VSAPI PATTERN FILE: 16.498.07
FIRST VSAPI PATTERN DATE: 25 Jan 2021
VSAPI OPR PATTERN File: 16.499.00
VSAPI OPR PATTERN Date: 26 Jan 2021

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

Identify and terminate files detected as Ransom.PS1.NETWALKER.FA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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.  
  • %Desktop%\{Appended Extension}-Readme.txt
  • {Encrypted Directory}\{Appended Extension}-Readme.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.PS1.NETWALKER.FA. 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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