Ransom.Win32.NETWALKER.YPAA-A
Trojan:Win32/Nemty.PD!MTB(MICROSOFT); HEUR:Trojan.Win32.DelShad.vho (KASPERSKY)
Windows

Threat Type: Ransomware
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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
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
SOLUTION
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
Step 5
Delete this registry value
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
- {8 random characters} = "%Program Files%\{8 random characters}\{8 random characters}.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- {8 random characters} = "%Application Data%\{8 random characters}\{8 random characters}.exe
- {8 random characters} = "%Application Data%\{8 random characters}\{8 random characters}.exe
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- {8 random characters} = "%Program Files%\{8 random characters}\{8 random characters}.exe
- {8 random characters} = "%Program Files%\{8 random characters}\{8 random characters}.exe
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- {8 random characters} = "%Application Data%\{8 random characters}\{8 random characters}.exe
- {8 random characters} = "%Application Data%\{8 random characters}\{8 random characters}.exe
Step 6
Delete this registry key
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}
- In HKEY_CURRENT_USER\software
- {8 random characters}
- {8 random characters}
Step 7
Search and delete this folder
- %Program Files%\{8 random characters}
- %Application Data%\{8 random characters}
Step 8
Search and delete these files
- {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.NETWALKER.YPAA-A. 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.
Step 11
Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.NETWALKER.YPAA-A. 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:
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