Ransom.Win32.TFLOWER.A

 Analysis by: John Rey Canon

 ALIASES:

Trojan.Win32.DelShad.aex (Kaspersky); Ransom.FileCryptor (Malwarebytes)

 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


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 encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

1,102,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Aug 2019

Payload:

Encrypts files, Connects to URLs/IPs, Displays message/message boxes

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 adds the following processes:

  • bcdedit.exe /set {default} recoveryenabled no
  • bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit.exe /set {current} recoveryenabled no
  • bcdedit.exe /set {current} bootstatuspolicy ignoreallfailures
  • vssadmin.exe delete shadows /all /quiet -> Deletes Shadow Copy

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
{Random Text} = {malware location}\{malware name}.exe

Other Details

This Ransomware does the following:

  • It connects to the following URL:
    • https://www.{BLOCKED}ofacilesicuro.com/wp-content/plugins/wp-statistics/{BLOCKED}l.php
  • It adds encryption marker at the start of the file:
    • *tflower

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • 0
  • 00
  • 000
  • 001
  • 002
  • 003
  • 01
  • 1
  • 3gp
  • 7z
  • a
  • a3m
  • a3w
  • a4m
  • a4p
  • a4w
  • a5w
  • aam
  • aas
  • abk
  • abs
  • ace
  • ada
  • adb
  • adf
  • adi
  • aep
  • af2
  • af3
  • ai
  • aif
  • aifc
  • aiff
  • aim
  • ais
  • akd
  • all
  • ams
  • anc
  • apk
  • aps
  • ari
  • arj
  • array
  • art
  • asa
  • asc
  • asd
  • asf
  • asm
  • asp
  • asx
  • atw
  • au
  • avi
  • avr
  • backup
  • bak
  • bas
  • bat
  • bdf
  • bgl
  • bhd
  • bi
  • bif
  • bik
  • bin
  • bip
  • bk
  • bkf
  • bks
  • bmp
  • book
  • brdf
  • brx
  • bsp
  • btm
  • bud
  • bw
  • bwv
  • c
  • cab
  • cad
  • cal
  • cap
  • cc
  • ccb
  • cch
  • cco
  • cct
  • cda
  • cdf
  • cdi
  • cdm
  • cdr
  • cdt
  • cdx
  • cer
  • cert
  • cfg
  • cgi
  • cgm
  • chk
  • chm
  • ci
  • cif
  • cil
  • class
  • cll
  • cls
  • cmd
  • cmf
  • cmv
  • cmx
  • cnf
  • cod
  • config
  • content
  • cpp
  • cpr
  • cpt
  • cpx
  • crd
  • crp
  • crt
  • cs
  • csc
  • csp
  • cst
  • csv
  • ctl
  • cxx
  • dae
  • dat
  • db
  • dbc
  • dbf
  • dbx
  • dcm
  • dcs
  • dct
  • dcu
  • dcx
  • dds
  • dek
  • dem
  • dep
  • der
  • dewf
  • dex
  • dib
  • dif
  • dig
  • dir
  • dll
  • doc
  • docx
  • dod
  • dor
  • dot
  • dps
  • draw
  • drv
  • drw
  • dsf
  • dsg
  • dsm
  • dsp
  • dsq
  • dsw
  • dtd
  • dv
  • dxr
  • eda
  • edb
  • emf
  • eml
  • epr
  • eps
  • exe
  • fax
  • fbx
  • fcd
  • fla
  • flc
  • flo
  • flv
  • gdb
  • gho
  • gif
  • gl
  • go
  • grp
  • gz
  • h
  • hipnc
  • hpp
  • ht
  • htm
  • html
  • htx
  • hwp
  • icc
  • icm
  • ico
  • idf
  • idx
  • incf
  • inf
  • ini
  • inp
  • iso
  • jar
  • java
  • jbf
  • jf
  • jfif
  • jif
  • jpe
  • jpeg
  • jpg
  • js
  • json
  • jsp
  • jtd
  • jtf
  • kar
  • kbx
  • kdb
  • kdbx
  • key
  • lab
  • ldf
  • lib
  • log
  • lst
  • m1v
  • m3u
  • mad
  • maf
  • mam
  • map
  • maq
  • mar
  • mat
  • max
  • mbx
  • md5
  • mdb
  • mdf
  • mdbx
  • mid
  • mkv
  • mli
  • mod
  • mor
  • mov
  • mp2
  • mp3
  • mp4
  • mpa
  • mpe
  • mpeg
  • mpg
  • mpp
  • mrimg
  • msg
  • msi
  • mst
  • mxf
  • ncb
  • nds
  • obj
  • ocx
  • ods
  • odt
  • ogg
  • olb
  • ole
  • olp
  • ora
  • p12
  • pak
  • pas
  • pbd
  • pbl
  • pdf
  • pem
  • pfx
  • php
  • php3
  • phtml
  • pic
  • pjt
  • pjx
  • pkg
  • png
  • pot
  • ppk
  • pps
  • ppt
  • pptx
  • prfpset
  • propert
  • prproj
  • psd
  • psp
  • pub
  • py
  • pyc
  • pyw
  • qic
  • qif
  • ra
  • ram
  • rar
  • rb
  • rdf
  • rdg
  • reg
  • res
  • rm
  • rsrc
  • rtf
  • s
  • sav
  • sbl
  • scc
  • sfx
  • sh
  • shtml
  • shw
  • sid
  • ska
  • so
  • spl
  • sqc
  • sql
  • sqlite
  • sqr
  • swa
  • swf
  • sys
  • tar
  • taz
  • tga
  • tgz
  • thn
  • tif
  • tiff
  • tlb
  • tlog
  • tmp
  • tps
  • trm
  • ttf
  • txt
  • udk
  • ult
  • upk
  • url
  • vbp
  • vbs
  • vbw
  • vbx
  • vct
  • vdi
  • vhd
  • vhdx
  • vir
  • viv
  • vob
  • vsd
  • vss
  • vxd
  • w3l
  • wab
  • wad
  • war
  • wav
  • wbem
  • wbk
  • wcm
  • wdb
  • wid
  • wil
  • wiz
  • wll
  • wmf
  • wmv
  • wow
  • wp
  • wpd
  • wpf
  • wpg
  • wps
  • wpt
  • x
  • xar
  • xla
  • xlb
  • xlc
  • xld
  • xlk
  • xll
  • xlm
  • xlo
  • xls
  • xlsx
  • xlt
  • xlv
  • xlw
  • xml
  • xmp
  • yaml
  • z
  • zap
  • zip
  • ztl

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

  • sample music
  • windows
  • !_Notice_!.txt
  • {malware filename}

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

  • {Infected Directory}\!_Notice_!.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.282.08

FIRST VSAPI PATTERN DATE:

06 Aug 2019

VSAPI OPR PATTERN File:

15.283.00

VSAPI OPR PATTERN Date:

07 Aug 2019

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

Restart in Safe Mode

[ Learn More ]

Step 4

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
    • {random text} = {malware location}\{malware name}.exe

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.TFLOWER.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 6

Restore encrypted files from backup.


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