Ransom.VBS.NETWALKER.YAAC-A

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 encrypts files with specific file extensions. It drops files as ransom note.

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 character}.tmp.bat → terminates malware process and deletes malware file
• {Enrypted Directory}\{6 Random Characters}-Readme.txt → Ransom Note

(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 drops and executes the following files:

• %User Temp%\qeSw.exe

(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:

• %User Temp%\qeSw.exe
• "%System%\vssadmin delete shadows /all /quiet
• %System%\notepad.exe "%Desktop%\{6 random characters}-Readme.txt"
• cmd /c "%User Temp%\{4 random character}.tmp.bat" → terminates malware process and deletes malware file

(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).. %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).)

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:

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

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

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

Other Details

This Ransomware deletes itself after execution.

Ransomware Routine

This Ransomware encrypts files with the following 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

It 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.mp"
• "*msocache.
• "*:\winnt."
• "*$windows.~ws.
• "*perflogs.
• "*boot.
• "*:\windows."
• "*:\program file*\vmware.e"
• "\*\users\*\*temp.temp"
• "\*\winnt.nt"
• "\*\windows.ws"
• "*\program file*\vmware.e"
• "*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.t"
• "*\program file*\windows photo*.*"
• "*\program file*\windows side*.*"
• "*\program file*\windowspowershell.l"
• "*\program file*\cuass*.*"
• "*\program file*\microsoft games.s"
• "*\program file*\common files\system.em"
• "*\program file*\common files\*shared.ed"
• "*\programfile*\common files\reference ass*.s*"
• "*\windows\cache*.*"
• "*temporary internet*.
• "*media player.
• "*:\users\*\appdata\*\microsoft.soft"
• "\*\users\*\appdata\*\microsoft.rosoft"

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

• {6 random characters}

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

• {Enrypted Directory}\{6 Random Characters}-Readme.txt

It leaves text files that serve as ransom notes containing the following text: