Analysis by: Neljorn Nathaniel Aguas
ALIASES:

VHO:Trojan-Ransom.Win32.Conti.bn (KASPERSKY)

 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, 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 does not have any propagation routine.

It does not have any backdoor routine.

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

  TECHNICAL DETAILS

File Size: 249,856 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 08 Sep 2023
Payload: Encrypts files, Displays message/message boxes, Abuses WMI

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 files:

  • {Malware File Path}\{Log File Name} → If the parameter -log {Log File Name} is used
  • {Log File Path}\{Log File Name} → If the parameter -log {Log File Path}\{Log File Name} is used

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

  • hsfjuukjzloqu28oajh727190

Other System Modifications

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

  • cmd.exe /c %System%\wbem\WMIC.exe shadowcopy where "ID='{GUID}'" delete

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

Propagation

This Ransomware does not have any propagation routine.

Backdoor Routine

This Ransomware does not have any backdoor routine.

Rootkit Capabilities

This Ransomware does not have rootkit capabilities.

Other Details

This Ransomware does the following:

  • By default, it encrypts local drives, removable drives and network shares.
  • When encrypting network shares it will check if the IP address starts with the following to ensure that it is encrypting local, non-internet, systems:
    • 172.
    • 192.168.
    • 10.
    • 169.
  • It encrypts files with the following extensions using a different encryption method:
    • .4dd
    • .4dl
    • .abcddb
    • .abs
    • .abx
    • .accdb
    • .accdc
    • .accde
    • .accdr
    • .accdt
    • .accdw
    • .accft
    • .adb
    • .ade
    • .adf
    • .adn
    • .adp
    • .alf
    • .arc
    • .ask
    • .avdx
    • .avhd
    • .bdf
    • .bin
    • .btr
    • .cat
    • .cdb
    • .ckp
    • .cma
    • .cpd
    • .dacpac
    • .dad
    • .dadiagrams
    • .daschema
    • .db
    • .db-shm
    • .db-wal
    • .db2
    • .db3
    • .dbc
    • .dbf
    • .dbs
    • .dbt
    • .dbv
    • .dbx
    • .dcb
    • .dct
    • .dcx
    • .ddl
    • .dlis
    • .dp1
    • .dqy
    • .dsk
    • .dsn
    • .dtsx
    • .dxl
    • .eco
    • .ecx
    • .edb
    • .epim
    • .exb
    • .fcd
    • .fdb
    • .fic
    • .fm5
    • .fmp
    • .fmp12
    • .fmps1
    • .fol
    • .fp3
    • .fp4
    • .fp5
    • .fp7
    • .fpt
    • .frm
    • .gdb
    • .grbd
    • .gwi
    • .hdb
    • .his
    • .hjt
    • .ib
    • .icg
    • .icr
    • .idb
    • .ihx
    • .iso
    • .itdb
    • .itw
    • .jet
    • .jtx
    • .kdb
    • .kdb
    • .kexi
    • .kexic
    • .kexis
    • .lgc
    • .lut
    • .lwx
    • .maf
    • .maq
    • .mar
    • .mas
    • .mav
    • .maw
    • .mdb
    • .mdf
    • .mdn
    • .mdt
    • .mpd
    • .mrg
    • .mud
    • .mwb
    • .myd
    • .ndf
    • .nnt
    • .nrmlib
    • .ns2
    • .ns3
    • .ns4
    • .nsf
    • .nv
    • .nv2
    • .nvram
    • .nwdb
    • .nyf
    • .odb
    • .oqy
    • .ora
    • .orx
    • .owc
    • .p96
    • .p97
    • .pan
    • .pdb
    • .pdm
    • .pnz
    • .pvm
    • .qcow2
    • .qry
    • .qvd
    • .raw
    • .rbf
    • .rctd
    • .rod
    • .rodx
    • .rpd
    • .rsd
    • .sas7bdat
    • .sbf
    • .sbf
    • .scx
    • .scx
    • .sdb
    • .sdb
    • .sdc
    • .sdc
    • .sdf
    • .sis
    • .spq
    • .sql
    • .sqlite
    • .sqlite3
    • .sqlitedb
    • .subvol
    • .te
    • .temx
    • .tmd
    • .tps
    • .trc
    • .trm
    • .udb
    • .udl
    • .usr
    • .v12
    • .vdi
    • .vhd
    • .vhdx
    • .vis
    • .vmcx
    • .vmdk
    • .vmem
    • .vmrs
    • .vmsd
    • .vmsn
    • .vmx
    • .vpd
    • .vsv
    • .vvv
    • .wdb
    • .wmdb
    • .wrk
    • .xdb
    • .xld
    • .xmlff
  • It appends specific hex values to the encrypted files depending on their file size and extension.

It accepts the following parameters:

  • -p {Path} → Encrypts files in the specified path first before encrypting other paths
  • -m {all|local|net|backups}
    • local → delete backups and encrypt local drives
    • net → delete backups and encrypt only network shares
    • all → combination of net and local
    • backups → delete backups
  • -size {chunk mode} → chunk mode for encrypting large files
  • -nomutex → does not create mutex
  • -log {File name to create} → create a log file in {Malware File Path} unless a different file path is specified

It does not exploit any vulnerability.

Ransomware Routine

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

  • !!!-Restore-My-Files-!!!.txt
  • CONTI_LOG.txt

It avoids encrypting files found in the following folders:

  • tmp
  • winnt
  • temp
  • thumb
  • $Recycle.Bin
  • $RECYCLE.BIN
  • System Volume Information
  • Boot
  • Windows
  • Trend Micro
  • perflogs

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

  • .098fd602

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

  • {Drive Letter}:\!!!-Restore-My-Files-!!!.txt
  • {Directory with Encrypted Files}\!!!-Restore-My-Files-!!!.txt
  • %Desktop%\!!!-Restore-My-Files-!!!.txt

It avoids encrypting files with the following file extensions:

  • .exe
  • .dll
  • .lnk
  • .sys
  • .msi
  • .bat
  • .098fd602

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.684.03
FIRST VSAPI PATTERN DATE: 08 Sep 2023
VSAPI OPR PATTERN File: 18.685.00
VSAPI OPR PATTERN Date: 09 Sep 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:

     
    • Ransom.Win32.TRX.XXPE50FFF072

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.
  • {Drive Letter}:\!!!-Restore-My-Files-!!!.txt
  • {Directory with Encrypted Files}\!!!-Restore-My-Files-!!!.txt
  • %Desktop%\!!!-Restore-My-Files-!!!.txt
  • {Malware File Path}\{Log File Name}
  • {Log File Path}\{Log File Name}

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.LOCKBIT.YJDIHT. 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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