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Ransom.MSIL.WANNASCREAM.A

March 27, 2020
 Analysis by: Paul Steven Nadera
 ALIASES:

Trojan:MSIL/Filecoder.DSK!MTB (Microsoft); Trojan.Filecoder (Quickheal); Trojan-Ransom.FileCrypter (Ikarus)

 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, Dropped by other malware


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 connects to certain websites to send and receive information.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

28,672 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Feb 2020

Payload:

Drops files, Steals information, Connects to URLs/IPs

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:

  • %User Startup%\Runtime Broker.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

It adds the following processes:

  • "cmd.exe /c vssadmin.exe delete shadows /all /quiet"

Information Theft

This Ransomware steals the following information:

  • Operating System
  • CPU information
  • Public IP Address
  • Total Size of All Logical Drives
  • Machine Name
  • Volume Serial Number
  • Processor ID

Other Details

This Ransomware connects to the following website to send and receive information:

  • http://recoverydata.{BLOCKED}sting.com/db

Ransomware Routine

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

  • info.txt

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

  • C:\Windows
  • A:\
  • C:\Boot
  • boot
  • swapfile.sys
  • pagefile.sys
  • hiberfil.sys
  • BOOTNXT
  • boot.sdi
  • bootmgr
  • BOOTSECT.BAK

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

  • -id.[{generated ID from Volume Serial Number or Processor iD}].Email=[{BLOCKED}tharma24@cock.li].Harma

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

  • {infected folder}\info.txt
  • %User Startup%\WannaScream.hta

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.694.04

FIRST VSAPI PATTERN DATE:

19 Feb 2020

VSAPI OPR PATTERN File:

15.695.00

VSAPI OPR PATTERN Date:

20 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

Search and delete these files

[ 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.
  • %User Startup%\WannaScream.hta

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.MSIL.WANNASCREAM.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 7

Restore encrypted files from backup.


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