Analysis by: Raymart Christian Yambot
ALIASES:

Win64:Malware-gen (AVAST)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

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

  TECHNICAL DETAILS

File Size: 1,273,344 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 23 Oct 2023
Payload: Collects system 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.

Information Theft

This Ransomware gathers the following data:

  • Username
  • Computer name
  • System total memory
  • System total used memory
  • System kernel version
  • Processor information
  • Operating system version
  • All drives available space

Other Details

This Ransomware accepts the following parameters:

  • -d, --debug - Activate debug mode
  • --fast - Activate fast mode
  • -h, --help - Prints help information
  • -v, --version - Prints version infromation
  • -e, --exclude {File path} - Exclude file for encryption
  • -p, -paths {Directory} - Encrypts the specified directory
  • --raise-priv {true/false} - Execute with admin privilege (Default: true)
  • --no-vss {true/false}} - Delete shadow copies (Default: true)
  • -t, --threads {Thread count} - Sets the number of thread used for encryption (Default: 0)
  • -f, --only-files {File} - Encrypts the specified file
  • -k, -kill-processes

Ransomware Routine

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

  • !losttrustencoded.txt
  • autorun.inf
  • boot.ini
  • bootfont.bin
  • bootsect.bak
  • desktop.ini
  • iconcache.db
  • ntldr,ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db
  • bootmgr
  • ! cynet ransom protection(don't delete)

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

  • $recycle.bin
  • windows\system32
  • \windows\syswow64\
  • \windows\system\
  • \windows\winsxs\
  • \system\msadc\
  • \common files\
  • \windowspowershell\
  • \program files\internet explorer\
  • \program files\microsoft games\
  • \all users\microsoft\
  • \inetpub\logs\
  • :\boot\
  • :\system volume information\
  • :\drivers\
  • :\ws us\
  • \cache\
  • \cache2\
  • \far manager\
  • \ida 7.0\
  • \ida 6.8\
  • \default\extensions\
  • \temporary internet files\
  • \temp\
  • $windows.~bt
  • $windows.~ws
  • \google\
  • \mozilla\
  • \tor browser\
  • \windows.old\
  • \intel\
  • \msocache\
  • \perflogs\
  • \programdata\microsoft\
  • \application data\microsoft\
  • \all users\microsoft\
  • \roaming\microsoft\
  • \local\microsoft\
  • \local settings\microsoft\
  • \locallow\microsoft\
  • \common\microsoft\
  • sophos
  • symantec
  • leaked
  • mozilla firefox
  • system volume in formation

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

  • .losttrustencoded2

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

  • {All Directories}\!losttrustencoded.txt

It avoids encrypting files with the following file extensions:

  • exe
  • dll
  • ocx
  • ani
  • cab
  • cpl
  • cur
  • diagcab
  • diagpkg
  • drv
  • hlp
  • icl
  • icns
  • ico
  • ics
  • lnk
  • idx
  • mod
  • mpa
  • msc
  • msp
  • msstyles
  • msu
  • nomedia
  • prf
  • rom
  • rtp
  • scr
  • shs
  • spl
  • sys
  • theme
  • themepack
  • deskthemepack
  • bat
  • cmd
  • url
  • mui
  • inf
  • pf
  • ntldr
  • nls
  • hta
  • ax
  • msi
  • mst
  • iso

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.790.02
FIRST VSAPI PATTERN DATE: 31 Oct 2023
VSAPI OPR PATTERN File: 18.790.02
VSAPI OPR PATTERN Date: 01 Nov 2023

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.XXPE50FFF075

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

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.  
  • {All Directories}\!losttrustencoded.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.LOSTTRUST.THJCABC. 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 6

Restore encrypted files from backup.


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