RANSOM_KASISKI.A

 Analysis by: John Anthony Banes

 ALIASES:

Trojan.Ransom.Kasiski (ALYac); Python/Filecoder.Kasiski.A (ESET-NOD32); Python/Filecoder_Kasiski.A!tr (Fortinet); Ransom.Kasiski (Malwarebytes)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It is capable of encrypting files in the affected system.

  TECHNICAL DETAILS

File Size:

14,648,721 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Feb 2017

Payload:

Encrypts files, Drops files

Arrival Details

This Trojan 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 Trojan drops the following files:

  • C:\Programfiles\DOCS_r\R\S\W\CURRICULUM.pdf
  • {malware path}\key.txt
  • C:\Programfiles\DOCS_r\R\S\W\dis.txt
  • {malware path}\wpm.jpg - ransom note wallpaper
  • {malware path}\INSTRUCCIONES.txt - ransom note

Other Details

This Trojan encrypts files with the following extensions:

  • aes
  • ARC
  • asc
  • asf
  • asm
  • asp
  • avi
  • bak
  • bat
  • bmp
  • brd
  • bz2
  • cgm
  • class
  • cmd
  • cpp
  • crt
  • csr
  • CSV
  • dbf
  • dch
  • dif
  • dip
  • djv
  • djvu
  • DOC
  • docb
  • docm
  • docx
  • DOT
  • dotm
  • dotx
  • fla
  • flv
  • frm
  • gif
  • gpg
  • hwp
  • ibd
  • jar
  • java
  • jpeg
  • jpg
  • key
  • lay
  • lay6
  • ldf
  • max
  • mdb
  • mdf
  • mid
  • mkv
  • mml
  • mov
  • mpeg
  • mpg
  • ms11
  • MYD
  • MYI
  • NEF
  • odb
  • odg
  • odp
  • ods
  • odt
  • otg
  • otp
  • ots
  • ott
  • PAQ
  • pas
  • pdf
  • pem
  • php
  • png
  • pot
  • potm
  • potx
  • ppam
  • pps
  • ppsm
  • ppsx
  • PPT
  • pptm
  • pptx
  • psd
  • qcow2
  • rar
  • raw
  • RTF
  • sch
  • sldm
  • sldx
  • slk
  • sql
  • SQLITE3
  • SQLITEDB
  • stc
  • std
  • sti
  • stw
  • svg
  • swf
  • sxc
  • sxd
  • sxi
  • sxm
  • sxw
  • tar
  • tar
  • tbk
  • tgz
  • tif
  • tiff
  • uop
  • uot
  • vbs
  • vdi
  • vmdk
  • vmx
  • vob
  • wav
  • wks
  • wma
  • wmv
  • xlc
  • xlm
  • XLS
  • xlsb
  • xlsm
  • xlsx
  • xlt
  • xltm
  • xltx
  • xlw
  • xml
  • zip

It renames encrypted files using the following names:

  • [KASISKI]{original filename}

It does the following:

  • It sends the message "hello : my friend" to this email address: pfi333555@gmail.com
  • It encrypts files on drives C:, D:, E:, and F:

It is capable of encrypting files in the affected system.

NOTES:

The wallpaper contains the following message:

    TODOS SUS ARCHIVOS FUERON ENCRYPTADOS

    TODOS SUS ARCHIVOS FUERON ENCRYPTADOS

    PARA RECUPERARLOS ABRA EL DOCUMENTO

    'INSTRUCCIONES.txt' QUE SE ENCUENTRA EN SU

    ESCRITORIO Y SIGA LAS INSTRUCCIONES QUE

    ALLI LE INDICA.

The ransom note contains the following message:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.228.00

FIRST VSAPI PATTERN DATE:

17 Feb 2017

VSAPI OPR PATTERN File:

13.229.00

VSAPI OPR PATTERN Date:

18 Feb 2017

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

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:\Programfiles\DOCS_r\R\S\W\CURRICULUM.pdf
  • C:\ProgramFiles\DOCS_r\R\S\W\dis.txt
  • {malware path}\wpm.jpg
  • {malware path}\INSTRUCCIONES.txt
  • {malware path}\key.txt

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • C:\Programfiles

Step 5

Reset your Desktop properties

[ Learn More ]

Step 6

Scan your computer with your Trend Micro product to delete files detected as RANSOM_KASISKI.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 7

Restore encrypted files from backup.


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