Ransom.Win32.SAMSAM.THGOHAI

 Analysis by: Earle Maui Earnshaw

 ALIASES:

Ransom:MSIL/Samas.A(Microsoft); MSIL/FilecoderSamas.A!tr.ransom(Fortinet)

 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:

Dropped by other malware, 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:

56,320 bytes

File Type:

EXE

Initial Samples Received Date:

08 Jul 2019

Payload:

Connects to URLs/IPs

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 and executes the following files:

  • {malware path}\selfdel.exe

Other Details

This Ransomware does the following:

  • Uses Bitcoin Address: {BLOCKED}DLTzkkT1uQrMPM42AUvfQN4Kds
  • Uses C2 server: http://{BLOCKED}39k.wordpress.com

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • xls
  • xlsx
  • pdf
  • doc
  • docx
  • ppt
  • pptx
  • txt
  • dwg
  • bak
  • bkf
  • pst
  • dbx
  • zip
  • rar
  • mdb
  • asp
  • aspx
  • html
  • htm
  • dbf
  • 3dm
  • 3ds
  • 3fr
  • jar
  • 3g2
  • xml
  • png
  • tif
  • 3gp
  • java
  • jpe
  • jpeg
  • jpg
  • jsp
  • php
  • 3pr
  • 7z
  • ab4
  • accdb
  • accde
  • accdr
  • accdt
  • ach
  • kbx
  • acr
  • act
  • adb
  • ads
  • agdl
  • ai
  • ait
  • al
  • apj
  • arw
  • asf
  • asm
  • asx
  • avi
  • awg
  • back
  • backup
  • backupdb
  • pbl
  • bank
  • bay
  • bdb
  • bgt
  • bik
  • bkp
  • blend
  • bpw
  • c
  • cdf
  • cdr
  • cdr3
  • cdr4
  • cdr5
  • cdr6
  • cdrw
  • cdx
  • ce1
  • ce2
  • cer
  • cfp
  • cgm
  • cib
  • class
  • cls
  • cmt
  • cpi
  • cpp
  • cr2
  • craw
  • crt
  • crw
  • phtml
  • php5
  • cs
  • csh
  • csl
  • tib
  • csv
  • dac
  • db
  • db3
  • db-journal
  • dc2
  • dcr
  • dcs
  • ddd
  • ddoc
  • ddrw
  • dds
  • der
  • des
  • design
  • dgc
  • djvu
  • dng
  • dot
  • docm
  • dotm
  • dotx
  • drf
  • drw
  • dtd
  • dxb
  • dxf
  • dxg
  • eml
  • eps
  • erbsql
  • erf
  • exf
  • fdb
  • ffd
  • fff
  • fh
  • fmb
  • fhd
  • fla
  • flac
  • flv
  • fpx
  • fxg
  • gray
  • grey
  • gry
  • h
  • hbk
  • hpp
  • ibank
  • ibd
  • ibz
  • idx
  • iif
  • iiq
  • incpas
  • indd
  • kc2
  • kdbx
  • kdc
  • key
  • kpdx
  • lua
  • m
  • m4v
  • max
  • mdc
  • mdf
  • mef
  • mfw
  • mmw
  • moneywell
  • mos
  • mov
  • mp3
  • mp4
  • mpg
  • mrw
  • msg
  • myd
  • nd
  • ndd
  • nef
  • nk2
  • nop
  • nrw
  • ns2
  • ns3
  • ns4
  • nsd
  • nsf
  • nsg
  • nsh
  • nwb
  • nx2
  • nxl
  • nyf
  • oab
  • obj
  • odb
  • odc
  • odf
  • odg
  • odm
  • odp
  • ods
  • odt
  • oil
  • orf
  • ost
  • otg
  • oth
  • otp
  • ots
  • ott
  • p12
  • p7b
  • p7c
  • pab
  • pages
  • pas
  • pat
  • pcd
  • pct
  • pdb
  • pdd
  • pef
  • pem
  • pfx
  • pl
  • plc
  • pot
  • potm
  • potx
  • ppam
  • pps
  • ppsm
  • ppsx
  • pptm
  • prf
  • ps
  • psafe3
  • psd
  • pspimage
  • ptx
  • py
  • qba
  • qbb
  • qbm
  • qbr
  • qbw
  • qbx
  • qby
  • r3d
  • raf
  • rat
  • raw
  • rdb
  • rm
  • rtf
  • rw2
  • rwl
  • rwz
  • s3db
  • sas7bdat
  • say
  • sd0
  • sda
  • sdf
  • sldm
  • sldx
  • sql
  • sqlite
  • sqlite3
  • sqlitedb
  • sr2
  • srf
  • srt
  • srw
  • st4
  • st5
  • st6
  • st7
  • st8
  • std
  • sti
  • stw
  • stx
  • svg
  • swf
  • sxc
  • sxd
  • sxg
  • sxi
  • sxi
  • sxm
  • sxw
  • tex
  • tga
  • thm
  • tlg
  • vob
  • war
  • wallet
  • wav
  • wb2
  • wmv
  • wpd
  • wps
  • x11
  • x3f
  • xis
  • xla
  • xlam
  • xlk
  • xlm
  • xlr
  • xlsb
  • xlsm
  • xlt
  • xltm
  • xltx
  • xlw
  • ycbcra
  • yuv

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

  • Windows
  • Reference Assemblies\Microsoft
  • Recycle.Bin

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

  • .encryptedRSA

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

  • {encrypted directory}\HELP_DECRYPT_YOUR_FILES.HTML

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.222.03

FIRST VSAPI PATTERN DATE:

08 Jul 2019

VSAPI OPR PATTERN File:

15.223.00

VSAPI OPR PATTERN Date:

09 Jul 2019

Step 1

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 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

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete this file

[ 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.  
  • {malware path}\selfdel.exe
  • {encrypted directories}\HELP_DECRYPT_YOUR_FILES.html

Step 5

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