Analysis by: Paul Steven Nadera
ALIASES:

Trojan.Win32.DelShad.cmy (Kaspersky);

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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 steals certain information from the system and/or the user.

It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 242,176 bytes
File Type: EXE
File Compression: UPX
Memory Resident: Yes
Initial Samples Received Date: 13 Feb 2020
Payload: Connects to URLs/IPs, Terminates processes, Steals information, Encrypts files

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 and executes the following files:

  • C:\Users\Public\Documents\wonsys.exe -> detected as Ransom.Win32.ANTEFRIGUS.A

It adds the following processes:

  • cmd /c taskkill /F /IM isqlplussvc.exe
  • cmd /c taskkill /F /IM xfssvccon.exe
  • cmd /c taskkill /F /IM mydesktopservice.exe
  • cmd /c taskkill /F /IM ocautoupds.exe
  • cmd /c taskkill /F /IM encsvc.exe
  • cmd /c taskkill /F /IM tbirdconfig.exe
  • cmd /c taskkill /F /IM mydesktopqos.exe
  • cmd /c taskkill /F /IM ocomm.exe
  • cmd /c taskkill /F /IM dbeng50.exe
  • cmd /c taskkill /F /IM sqbcoreservice.exe
  • cmd /c taskkill /F /IM excel.exe
  • cmd /c taskkill /F /IM infopath.exe
  • cmd /c taskkill /F /IM msaccess.exe
  • cmd /c taskkill /F /IM mspub.exe
  • cmd /c taskkill /F /IM onenote.exe
  • cmd /c taskkill /F /IM outlook.exe
  • cmd /c taskkill /F /IM powerpnt.exe
  • cmd /c taskkill /F /IM steam.exe
  • cmd /c taskkill /F /IM thebat.exe
  • cmd /c taskkill /F /IM thunderbird.exe
  • cmd /c taskkill /F /IM visio.exe
  • cmd /c taskkill /F /IM winword.exe
  • cmd /c taskkill /F /IM wordpad.exe
  • cmd /c taskkill /F /IM notepad.exe
  • cmd /c taskkill /F /IM aupis80.exe
  • cmd /c taskkill /F /IM avgnt.exe
  • cmd /c taskkill /F /IM sql.exe
  • cmd /c taskkill /F /IM oracle.exe
  • cmd /c taskkill /F /IM ocssd.exe
  • cmd /c taskkill /F /IM dbsnmp.exe
  • cmd /c taskkill /F /IM synctime.exe
  • cmd /c taskkill /F /IM agntsvc.exe
  • cmd /c wmic.exe shadowcopy delete
  • cmd /c start news.html
  • cmd /c {Root Drive}:/CLICK_HERE-{extension}.txt
  • cmd /c taskkill /F /IM isqlplussvc.exe
  • cmd /c taskkill /F /IM xfssvccon.exe
  • cmd /c taskkill /F /IM mydesktopservice.exe
  • cmd /c taskkill /F /IM ocautoupds.exe
  • cmd /c taskkill /F /IM encsvc.exe
  • cmd /c taskkill /F /IM tbirdconfig.exe
  • cmd /c taskkill /F /IM mydesktopqos.exe
  • cmd /c taskkill /F /IM ocomm.exe
  • cmd /c taskkill /F /IM dbeng50.exe
  • cmd /c taskkill /F /IM sqbcoreservice.exe
  • cmd /c taskkill /F /IM excel.exe
  • cmd /c taskkill /F /IM infopath.exe
  • cmd /c taskkill /F /IM msaccess.exe
  • cmd /c taskkill /F /IM mspub.exe
  • cmd /c taskkill /F /IM onenote.exe
  • cmd /c taskkill /F /IM outlook.exe
  • cmd /c taskkill /F /IM powerpnt.exe
  • cmd /c taskkill /F /IM steam.exe
  • cmd /c taskkill /F /IM thebat.exe
  • cmd /c taskkill /F /IM thunderbird.exe
  • cmd /c taskkill /F /IM visio.exe
  • cmd /c taskkill /F /IM winword.exe
  • cmd /c taskkill /F /IM wordpad.exe
  • cmd /c taskkill /F /IM notepad.exe
  • cmd /c taskkill /F /IM aupis80.exe
  • cmd /c taskkill /F /IM avgnt.exe
  • cmd /c taskkill /F /IM sql.exe
  • cmd /c taskkill /F /IM oracle.exe
  • cmd /c taskkill /F /IM ocssd.exe
  • cmd /c taskkill /F /IM dbsnmp.exe
  • cmd /c taskkill /F /IM synctime.exe
  • cmd /c taskkill /F /IM agntsvc.exe
  • cmd /c wmic.exe shadowcopy delete
  • cmd /c start news.html
  • cmd /c {Root Drive}:/CLICK_HERE-{extension}.txt

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
DefenIfWIn = C:\Users\Public\Documents\wonsys.exe"

Other System Modifications

This Ransomware uses Windows Management Instrumentation (WMI) to delete volume shadow copies:

  • cmd /c wmic.exe shadowcopy delete

Process Termination

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

  • isqlplussvc.exe
  • xfssvccon.exe
  • mydesktopservice.exe
  • ocautoupds.exe
  • encsvc.exe
  • tbirdconfig.exe
  • mydesktopqos.exe
  • ocomm.exe
  • dbeng50.exe
  • sqbcoreservice.exe
  • excel.exe
  • infopath.exe
  • msaccess.exe
  • mspub.exe
  • onenote.exe
  • outlook.exe
  • powerpnt.exe
  • steam.exe
  • thebat.exe
  • thunderbird.exe
  • visio.exe
  • winword.exe
  • wordpad.exe
  • notepad.exe
  • aupis80.exe
  • avgnt.exe
  • sql.exe
  • oracle.exe
  • ocssd.exe
  • dbsnmp.exe
  • synctime.exe
  • agntsvc.exe

Download Routine

This Ransomware accesses the following websites to download files:

  • https://{BLOCKED}er.org/1Jgt37

Information Theft

This Ransomware steals the following information:

  • Fixed Drives' Total Space and Remaining Space
  • Username

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file path:

  • windows
  • Windows
  • C:/intel
  • C:/nvidia
  • C:/ProgramData
  • Google
  • boot
  • C:/Program Files
  • C:/Program Files (x86)
  • System Volume Information
  • Mozilla
  • Tor Browser
  • Notepad
  • Explorer
  • Temp
  • temp
  • $
  • AndroidSDK

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

It avoids encrypting files with the following file extensions:

  • .md5
  • .sha1
  • .bin
  • .dll
  • .obj
  • .adv
  • .ani
  • .big
  • .bat
  • .cab
  • .cmd
  • .com
  • .cpl
  • .cur
  • .deskthemepack
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .drv
  • .hlp
  • .icl
  • .icns
  • .ics
  • “idx
  • .ldf
  • .mod
  • .mpa
  • .msc
  • .msp
  • .msstyles
  • .msu
  • .nls
  • .nomedia
  • .ocx
  • .prf
  • .ps1
  • .rom
  • .rtp
  • .scr
  • .shs
  • .spl
  • .sys
  • .theme
  • .themepack
  • .wpx
  • .lock
  • .key
  • .hta
  • .msi
  • .pck

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.684.05
FIRST VSAPI PATTERN DATE: 14 Feb 2020
VSAPI OPR PATTERN File: 15.685.00
VSAPI OPR PATTERN Date: 15 Feb 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.XXPE50FFF033

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\RunOnce
    • DefenIfWIn = "C:\Users\Public\Documents\wonsys.exe"

Step 6

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.
  • C:\Users\Public\Documents\wonsys.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.ANTEFRIGUS.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.


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