Ransom.Win32.NETWALKER.YPAA-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 drops files as ransom note. It avoids encrypting files with the following file extensions.

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
• %Application Data%\{8 characters}\{8 characters}.exe -> If it fails to drop a copy of itself in the %Program Files% directory

(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).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming 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%\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}
• %Application Data%\{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).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 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"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{8 random characters} = "%Program Files%\{8 random characters}\{8 random characters}.exe"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{8 random characters} = "%Application Data%\{8 random characters}\{8 random characters}.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{8 random characters} = "%Application Data%\{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}"

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 does the following:

• It deletes the created autorun registry and dropped copy if the encryption of all the files in the system is finished.
• For the registry keys/entries, it will only create a single entry which depends on the execution privilege of malware (either with administrative rights or not)

It deletes itself after execution.

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.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 renames encrypted files using the following names:

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

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

• {Enrypted Directory}\{5 Random Characters}-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