Ransom.MSIL.POVLSOM.THBAOBA

 Analysis by: Lorenzo Martin Lopez

 ALIASES:

Ransom:MSIL/Filecoder.EY!MTB (MICROSOFT), Trojan-Ransom.FileCrypter (IKARUS)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:
legend
  • others
    Threat Type: Ransomware
  • no
    Destructiveness: No
  • no
    Encrypted: No
  • in-the-wild
    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.

  TECHNICAL DETAILS

File Size:

38,400 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Feb 2021

Payload:

Displays graphics/image, Displays message/message boxes, 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.

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\Run
{Povlsomware, Sistem32, Servers, or other} = {Malware Filepath}\{Malware Filename}.exe

Other Details

This Ransomware displays the following images:

  • POVLSOM_THBAOBA1
  • POVLSOM_THBAOBA2
  • POVLSOM_THBAOBA3
  • POVLSOM_THBAOBA4
  • POVLSOM_THBAOBA5

It encrypts files with the following extensions:

  • 7z
  • 1cd
  • 3fr
  • 3g2
  • 3gp
  • 7z
  • accdb
  • ai
  • apk
  • arch00
  • ari
  • arw
  • asf
  • asp
  • aspx
  • asset
  • avi
  • bar
  • bat
  • bay
  • bc6
  • bc7
  • big
  • bik
  • bkf
  • bkp
  • blob
  • bmp
  • bsa
  • cad
  • cas
  • cdn
  • cdr
  • cer
  • cf
  • cfe
  • cfg
  • cfr
  • cfu
  • cr2
  • crt
  • crw
  • cs
  • css
  • csv
  • cxi
  • d3dbsp
  • das
  • dazip
  • db0
  • dba
  • dbf
  • dcr
  • der
  • desc
  • divx
  • dmp
  • dng
  • doc
  • docm
  • docx
  • dt
  • dwg
  • dxf
  • dxg
  • eip
  • epf
  • epk
  • eps
  • erf
  • esm
  • exe
  • ff
  • fff
  • flv
  • forge
  • fos
  • fpk
  • fsh
  • gdb
  • gho
  • gif
  • gpx
  • grs
  • hkdb
  • hkx
  • hplg
  • html
  • hvpl
  • ibank
  • icxs
  • iiq
  • img
  • indd
  • index
  • ini
  • itdb
  • itl
  • itm
  • iwd
  • iwi
  • j6i
  • jpe
  • jpeg
  • jpg
  • js
  • k25
  • kdb
  • kdc
  • key
  • kf
  • kml
  • kmz
  • layout
  • lbf
  • litemod
  • lnk
  • lrf
  • ltx
  • lvl
  • m2
  • m3u
  • m4a
  • m4v
  • map
  • mcmeta
  • md
  • mdb
  • mdbackup
  • mddata
  • mdf
  • mef
  • menu
  • mfw
  • mkv
  • mlx
  • mos
  • mov
  • mp3
  • mp4
  • mpeg
  • mpg
  • mpqge
  • mrw
  • mrwref
  • mxl
  • ncf
  • nef
  • nrg
  • nrw
  • ntl
  • odb
  • odc
  • odm
  • odp
  • ods
  • odt
  • ogg
  • orf
  • p12
  • p7b
  • p7c
  • pak
  • pdd
  • pdf
  • pef
  • pem
  • pfx
  • php
  • pk7
  • pkpass
  • png
  • pps
  • ppt
  • pptm
  • pptx
  • ps
  • psd
  • psk
  • pst
  • ptx
  • py
  • qdf
  • qic
  • r3d
  • raf
  • rar
  • raw
  • rb
  • re4
  • rgss3a
  • rim
  • rm
  • rofl
  • rtf
  • rw2
  • rwl
  • rwz
  • sav
  • sb
  • sid
  • sidd
  • sidn
  • sie
  • sis
  • slm
  • sln
  • snx
  • sql
  • sqlite
  • sqlite3
  • sr2
  • srf
  • srw
  • sum
  • svg
  • swf
  • syncdb
  • t12
  • t13
  • tax
  • tc
  • tga
  • tif
  • tiff
  • tor
  • txt
  • upk
  • vcf
  • vdf
  • vfs0
  • vob
  • vpk
  • vpp_pc
  • vtf
  • w3x
  • wallet
  • wav
  • wb2
  • wma
  • wmf
  • wmo
  • wmv
  • wotreplay
  • wpd
  • wps
  • x3f
  • xf
  • xlk
  • xlr
  • xls
  • xlsb
  • xlsm
  • xlsx
  • xml
  • xxx
  • zip
  • ztmp

It does the following:

  • creates autostart registries only if the filepath does not contain rundll32.exe
  • has several variations with different target extensions and avoided folders

Ransomware Routine

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

  • All Users\Microsoft\
  • $Recycle.Bin
  • C:\Windows
  • C:\Program Files
  • Temporary Internet Files
  • AppData\
  • \source\
  • C:\ProgramData\
  • \Povlsomware-master\
  • \Povlsomware\

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

  • Прочитай менЯ.txt
    povlosm_n
  • Наши контакты.txt
    povlosm_h
    povlosm_h2

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.528.07

FIRST VSAPI PATTERN DATE:

09 Feb 2021

VSAPI OPR PATTERN File:

16.529.00

VSAPI OPR PATTERN Date:

10 Feb 2021

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.XXPE50FFF041

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\Run
    • {Povlsomware, Sistem32, Servers, or other} = {Malware Filepath}\{Malware Filename}.exe

Step 6

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.  
  • Прочитай менЯ.txt
  • Наши контакты.txt

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.MSIL.POVLSOM.THBAOBA. 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 8

Restore encrypted files from backup.


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