RANSOM_SAMAS.K

June 19, 2017
 Analysis by: Joselyn Canuela
 ALIASES:

Ransom.Samas.Gen!c (AegisLab), MSIL/Filecoder_Samas.C!tr (Fortinet)

 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:

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:

179,712 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Jun 2017

Payload:

Terminates processes, 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.

Installation

This Ransomware drops and executes the following files:

  • C:\ProgramData\greenwin\startinfo.bat - batch file to delete itself

It creates the following folders:

  • C:\ProgramData\greenwin

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • sql

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .3dm
  • .3ds
  • .3fr
  • .3g2
  • .3gp
  • .3pr
  • .7z
  • .ab4
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .ach
  • .acr
  • .act
  • .adb
  • .ads
  • .agdl
  • .ai
  • .ait
  • .al
  • .apj
  • .arw
  • .asf
  • .asm
  • .asmx
  • .asp
  • .aspx
  • .asx
  • .avi
  • .awg
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bank
  • .bay
  • .bdb
  • .bgt
  • .bik
  • .bkf
  • .bkp
  • .blend
  • .bpw
  • .c
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfp
  • .cgm
  • .cib
  • .class
  • .cls
  • .cmt
  • .config
  • .cpi
  • .cpp
  • .cr2
  • .craw
  • .crt
  • .crw
  • .cs
  • .csh
  • .csl
  • .csv
  • .dac
  • .db
  • .db3
  • .dbf
  • .db-journal
  • .dbx
  • .dc2
  • .dcr
  • .dcs
  • .ddd
  • .ddoc
  • .ddrw
  • .dds
  • .der
  • .des
  • .design
  • .dgc
  • .djvu
  • .dng
  • .doc
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .drf
  • .drw
  • .dtd
  • .dwg
  • .dxb
  • .dxf
  • .dxg
  • .eml
  • .eps
  • .erbsql
  • .erf
  • .exf
  • .fdb
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fla
  • .flac
  • .flv
  • .fmb
  • .fpx
  • .fxg
  • .gray
  • .grey
  • .gry
  • .h
  • .hbk
  • .hpp
  • .htm
  • .html
  • .ibank
  • .ibd
  • .ibz
  • .idx
  • .iif
  • .iiq
  • .incpas
  • .indd
  • .jar
  • .java
  • .jpe
  • .jpeg
  • .jpg
  • .jsp
  • .kbx
  • .kc2
  • .kdbx
  • .kdc
  • .key
  • .kpdx
  • .lua
  • .m
  • .m4v
  • .max
  • .mdb
  • .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
  • .pbl
  • .pbl
  • .pcd
  • .pct
  • .pdb
  • .pdd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .php5
  • .phtml
  • .pl
  • .plc
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .prf
  • .ps
  • .psafe3
  • .psd
  • .pspimage
  • .pst
  • .ptx
  • .py
  • .qba
  • .qbb
  • .qbm
  • .qbr
  • .qbw
  • .qbx
  • .qby
  • .r3d
  • .raf
  • .rar
  • .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
  • .sxm
  • .sxw
  • .tex
  • .tga
  • .thm
  • .tib
  • .tif
  • .tlg
  • .txt
  • .vb
  • .vob
  • .wallet
  • .war
  • .wav
  • .wb2
  • .wmv
  • .wpd
  • .wps
  • .x11
  • .x3f
  • .xis
  • .xla
  • .xlam
  • .xlk
  • .xlm
  • .xlr
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .ycbcra
  • .yuv
  • .zip

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

  • .mention9823
  • startinfo.bat
  • READ-FOR-DECCCC-FILESSS.html
  • {malware name}.exe
  • desktop.ini
  • ntuser.dat
  • search-ms
  • .exe
  • .msi
  • .lnk
  • .wim
  • .scf
  • %System Root%
  • microsoft\windows
  • appdata
  • .ini
  • .sys
  • .dll

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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

  • .mention9823

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

  • %Desktop%\READ-FOR-DECCCC-FILESSS.html

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.476.08

FIRST VSAPI PATTERN DATE:

17 Jun 2017

VSAPI OPR PATTERN File:

13.477.00

VSAPI OPR PATTERN Date:

18 Jun 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 these folders

[ 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:\ProgramData\greenwin

Step 4

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.
  • %Desktop%\READ-FOR-DECCCC-FILESSS.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_SAMAS.K. 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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