Analysis by: Denisse Camille Layco
ALIASES:

W32/Sorena.AY!tr.ransom (FORTINET); Trojan-Ransom.FileCrypter (IKARUS)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • 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 drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 2,854,400 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 10 Nov 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.

Other System Modifications

This Ransomware deletes the following folders:

  • AppData in all users (with allowed permissions for Everyone)
  • {Drive letter}:\$Recycle.Bin

Process Termination

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

  • sqlservr.exe
  • sqlceip.exe
  • sqlwriter.exe

Other Details

This Ransomware does the following:

  • It avoids encrypting files with the following file names:
    • Unlock_All_Files.txt
    • Encrypt.exe
    • ngrok.exe

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • C:\Windows
  • C:\Program Files\VMWare
  • C:\Program Files\Common Files
  • C:\Program Files\Internet Explorer
  • C:\Program Files\Reference Assemblies
  • C:\Program Files (x86)\Reference Assemblies
  • C:\Program Files (x86)\Common Files
  • C:\Program Files (x86)\Internet Explorer
  • C:\Program Files\WindowsApps
  • C:\Program Files\Embedded Lockdown Manager
  • C:\ProgramData\Microsoft

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

  • .Email=[decryptfiles5@gmail.com]ID=[{unique ID}].encrypt

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

  • %Desktop%\Unlock_All_Files.txt
  • %Application Data%\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt
  • %Public%\Desktop\Unlock_All_Files.txt
  • %Public%\AppData\Roaming\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt
  • C:\Users\Default\Desktop\Unlock_All_Files.txt
  • C:\Users\Default\AppData\Roaming\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt

It avoids encrypting files with the following file extensions:

  • .ini
  • .log
  • .resources

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.442.06
FIRST VSAPI PATTERN DATE: 28 Dec 2020
VSAPI OPR PATTERN File: 16.443.00
VSAPI OPR PATTERN Date: 29 Dec 2020

Step 1

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 2

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 3

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.  
  • %Desktop%\Unlock_All_Files.txt
  • %Application Data%\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt
  • %Public%\Desktop\Unlock_All_Files.txt
  • %Public%\AppData\Roaming\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt
  • C:\Users\Default\Desktop\Unlock_All_Files.txt
  • C:\Users\Default\AppData\Roaming\Microsoft\Windows\Network Shortcuts\Unlock_All_Files.txt

Step 4

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.SORENA.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:

Step 5

Restore encrypted files from backup.


Did this description help? Tell us how we did.