Analysis by: Joshua Paul Ignacio


Trojan.Win32.DelShad.fod (KASPERSKY)




  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes


Infection Channel: 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 drops files as ransom note. It avoids encrypting files with the following file extensions.


File Size: 3,763,200 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 Dec 2020
Payload: Displays message/message boxes, Encrypts files, Terminates processes

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.


This Ransomware adds the following processes:

  • vssadmin.exe Resize ShadowStorage /for=c: /on=c: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=c: /on=c: /maxsize=unbounded
  • vssadmin.exe Resize ShadowStorage /for=d: /on=d: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=d: /on=d: /maxsize=unbounded
  • vssadmin.exe Resize ShadowStorage /for=e: /on=e: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=e: /on=e: /maxsize=unbounded
  • vssadmin.exe Resize ShadowStorage /for=f: /on=f: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=f: /on=f: /maxsize=unbounded
  • vssadmin.exe Resize ShadowStorage /for=g: /on=g: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=g: /on=g: /maxsize=unbounded
  • vssadmin.exe Resize ShadowStorage /for=h: /on=h: /maxsize=401MB
  • vssadmin.exe Resize ShadowStorage /for=h: /on=h: /maxsize=unbounded
  • vssadmin.exe Delete Shadows /All /Quiet
  • del /s /f /q c:\*.VHD c:\*.bac c:\*.bak c:\*.wbcat c:\*.bkf c:\Backup*.* c:\backup*.* c:\*.set c:\*.win c:\*.dsk
  • del /s /f /q d:\*.VHD d:\*.bac d:\*.bak d:\*.wbcat d:\*.bkf d:\Backup*.* d:\backup*.* d:\*.set d:\*.win d:\*.dsk
  • del /s /f /q e:\*.VHD e:\*.bac e:\*.bak e:\*.wbcat e:\*.bkf e:\Backup*.* e:\backup*.* e:\*.set e:\*.win e:\*.dsk
  • del /s /f /q f:\*.VHD f:\*.bac f:\*.bak f:\*.wbcat f:\*.bkf f:\Backup*.* f:\backup*.* f:\*.set f:\*.win f:\*.dsk
  • del /s /f /q g:\*.VHD g:\*.bac g:\*.bak g:\*.wbcat g:\*.bkf g:\Backup*.* g:\backup*.* g:\*.set g:\*.win g:\*.dsk
  • del /s /f /q h:\*.VHD h:\*.bac h:\*.bak h:\*.wbcat h:\*.bkf h:\Backup*.* h:\backup*.* h:\*.set h:\*.win h:\*.dsk
  • del %0
  • bcdedit.exe /set {default} recoveryenabled No
  • bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • wmic.exe SHADOWCOPY /nointeractive
  • %System%\cmd.exe /c del {Malware File Path}\{Malware File Name}.exe >>NUL → delete itself after execution

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {8761ABBD-7F85-42EE-B272-A76179687C63}

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

MSFEEditor = "{Malware File Path}\{Malware File Name.exe}" e

It starts the following services:

  • LanmanWorkstation

Other System Modifications

This Ransomware adds the following registry entries:

EnabledLinkedConnections = 1

Process Termination

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

  • ccEvtMgr
  • ccSetMgr
  • Culserver
  • DefWatch
  • Intuit.QuickBooks.FCS
  • MsDtsServer100
  • msmdsrv
  • MSSQLFDLauncher
  • MSSQLServerADHelper100
  • MSSQLServerOLAPService
  • QBCFMonitorService
  • QBIDPService
  • ReportServer
  • RTVscan
  • SavRoam
  • sqladhlp
  • sqlagent
  • sqlbrowser
  • SQLBrowser
  • sqlservr
  • sqlwriter
  • SQLWriter
  • wrapper

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

  • axlbridge.exe
  • Culture.exe
  • Defwatch.exe
  • fdhost.exe
  • fdlauncher.exe
  • httpd.exe
  • MsDtsSrvr.exe
  • onenotem.exe
  • QBCFMonitorService.exe
  • QBDBMgr.exe
  • QBIDPService.exe
  • qbupdate.xe
  • QBW32.exe
  • RAgui.exe
  • RTVscan.exe
  • sqlbrowser.exe
  • sqlmangr.exe
  • sqlservr.exe
  • sqlwriter.exe
  • ssms.exe
  • supervise.exe
  • winword.exe
  • Winword.exe
  • wxServer.exe
  • wxServerView

Dropping Routine

This Ransomware drops the following files:

  • %Application Data%\KEY.FILE

(Note: %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).)

Other Details

This Ransomware does the following:

  • This ransomware affects all existing drives in the system
  • It also encrypts files from network shares.
  • It uses Windows Restart Manager to unlock files it will encrypt.
  • It empties the recycle bin

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .inprocess
  • .ReadInstructions

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

  • %SystemRoot%\Recovery_Instructions.txt
  • {Drive Letter}:\Recovery_Instructions.txt
  • %Public%\Desktop\ Recovery_Instructions.txt

It avoids encrypting files with the following file extensions:

  • .TXT
  • .txt
  • .exe
  • .dll
  • .sys
  • .ini
  • .lnk
  • .dat


Minimum Scan Engine: 9.800
VSAPI OPR PATTERN File: 16.411.00
VSAPI OPR PATTERN Date: 14 Dec 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.XXPE50FFF039

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • MSFEEditor = {Malware File Path}\{Malware File Name.exe} e
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • EnabledLinkedConnections = 1

Step 6

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %SystemRoot%\Recovery_Instructions.txt
  • {Drive Letter}:\Recovery_Instructions.txt
  • %Public%\Desktop\ Recovery_Instructions.txt
  • %Application Data%\KEY.FILE

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win64.MEDUSALOCKER.AA. 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.


Do this after step 3:

  1. To restore bootmgr, insert your Windows installation DVD into your machine's CD-ROM drive.
  2. Restart the machine and press any key when Press any key to boot from CD or DVD appears.
  3. After selecting your language and keyboard options, click the link titled Repair your computer.
  4. Wait for Startup Repair to scan your PC, then select Startup Repair from the list of available recovery options to begin.
  5. Startup Repair will begin scanning your installation for known issues and will attempt a repair, if possible.

Did this description help? Tell us how we did.