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RANSOM_STRAWHAT.A

September 13, 2017
 Analysis by: Wilbert Vidal
 ALIASES:

Trojan.Ransom.StrawHat (ALYac); MSIL.Trojan-Ransom.StrawHat.A (GData)

 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, 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.

  TECHNICAL DETAILS

File Size:

192,000 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Aug 2017

Payload:

Renames files, Changes wallpaper

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.

Other Details

This Ransomware does the following:

  • The Ransomware renames files with specific file extensions:
    • .txt
    • .TXT
    • .pdf
    • .PDF
    • .zip
    • .ZIP
    • .docx
    • .DOCX
    • .xls
    • .XLS
    • .doc
    • .DOC
    • .jpg
    • .JPG
    • .png
    • .PNG
    • .ppt
    • .PPT
    • .pptx
    • .PPTX
    • .xlsx
    • .XLSX
    • .iso
    • .ISO
    • .ico
    • .ICO
    • .mp3
    • .MP3
    • .rar
    • .RAR
    • .jpeg
    • .JPEG
    • .bmp
    • .BMP
    • .raw
    • .RAW
    • .pps
    • .PPS
    • .cfg
    • .CFG
    • .wav
    • .WAV
    • .gif
    • .GIF
    • .pat
    • .pat
    • .rtf
    • .RTF
    • .ini
    • .INI
    • .cat
    • .CAT
    • .xml
    • .XML
    • .inf
    • .INF
    • .xlt
    • .xltx
    • .wma
    • .WMA
    • .flv
    • .FLV
    • .mkv
    • .MKV
    • .mov
    • .MOV
    • .avi
    • .AVI
    • .mpeg
    • .MPEG
    • .mpg
    • .MPG
    • .wmv
    • .WMV
    • .tif
    • TIF.
    • .mdb
    • .MDB
    • .sql
    • .SQL
    • .sqlitedb
    • .SQLITEDB
    • .sqlite3
    • .SQLITE3
    • pptm.
    • .PPTM
    • .xltm
    • .XLTM
    • .xlsm
    • .XLSM
    • .xlm
    • .XLM
    • .dotm
    • .DOTM
    • .dotx
    • .DOTX
    • .dot
    • .DOT
    • .csv
    • .CSV
    • .pem
    • .PEM
    • .csr
    • .CSR
    • .crt
    • .CRT
    • .key
    • .KEY
    • .mp4
    • .MP4
  • The Ransomware renames files found in a specific folder:
    • C:\test
  • The Ransomware renames files with random characters extension.

It locks the screen and displays the following image:

Ransomware Routine

This Ransomware drops the following file(s) as ransom note:

  • C:\test\YOUR_FILES_ARE_ENCRYPTED.html
  • C:\test\YOUR_FILES_ARE_ENCRYPTED.txt

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

NOTES:

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.622.08

FIRST VSAPI PATTERN DATE:

28 Aug 2017

VSAPI OPR PATTERN File:

13.623.00

VSAPI OPR PATTERN Date:

29 Aug 2017

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 XP, Windows Vista, and Windows 7 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.
  • C:\test\YOUR_FILES_ARE_ENCRYPTED.txt
  • C:\test\YOUR_FILES_ARE_ENCRYPTED.html

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_STRAWHAT.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.


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