Analysis by: Joselyn Canuela
ALIASES:

Trojan-Ransom.MSIL.Agent.gmt (Kaspersky), Ransom:Win32/Genasom (Microsoft), Ransom.FileLocker (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, 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 connects to certain websites to send and receive information.

It encrypts files with specific file extensions. It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size: 595,456 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 03 Oct 2017
Payload: 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 adds the following folders:

  • C:\Program Data\Keyboard -> log files are being saved

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
AESxWin = ”%Malware Path%\{malware file name}.exe”

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\AESxWin

It adds the following registry entries:

HKEY_CURRENT_USER\Software\AESxWin
ComputerId = "{GUID}"

Download Routine

This Ransomware accesses the following websites to download files:

  • http://{BLOCKED}y-office.eu/ww.txt

It saves the files it downloads using the following names:

  • %Application Data%\{random file name}.bat -> executed and deleted afterwards

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on 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.)

Other Details

This Ransomware connects to the following URL(s) to get the affected system's IP address:

  • https://v4.ident.me
  • https://api.ipify.org

It connects to the following website to send and receive information:

  • http://{BLOCKED}nty-office.eu/wdxx/
  • http://{BLOCKED}ty-office.eu/login/
  • https://{BLOCKED}nopl/ass/
  • https://{BLOCKED}oilapl/mi5/

It does the following:

  • It uses the following arguments:
    • /reg -> register the application in the system. It will create the following registry key
      • HKEY_CLASSES_ROOT\Directory\Background\shell\AESxWin
    • /unreg -> unregister the application in the system. It will delete the created registry key

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .1cd
  • .3ds
  • .3fr
  • .3g2
  • .3g2
  • .3gp
  • .3gp
  • .3pr
  • .7z
  • .7z
  • .7zip
  • .aac
  • .ab4
  • .acc
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .ach
  • .acr
  • .act
  • .adb
  • .adp
  • .ads
  • .agdl
  • .ai
  • .aiff
  • .ait
  • .al
  • .amr
  • .aoi
  • .apj
  • .arw
  • .asf
  • .asf
  • .asm
  • .asp
  • .aspx
  • .asx
  • .ath
  • .avi
  • .avi
  • .awg
  • .bac
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bay
  • .bdb
  • .bgt
  • .bik
  • .bin
  • .bkp
  • .blend
  • .bmp
  • .bpw
  • .c
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfg
  • .cgm
  • .cib
  • .class
  • .cls
  • .cmt
  • .config
  • .contact
  • .cpi
  • .cpp
  • .cpp
  • .cr2
  • .craw
  • .crt
  • .crw
  • .cs
  • .cs
  • .csh
  • .csl
  • .css
  • .css
  • .csv
  • .dac
  • .dat
  • .db
  • .db_journal
  • .db3
  • .dbf
  • .dbt
  • .dbx
  • .dc2
  • .dcr
  • .dcs
  • .ddd
  • .ddoc
  • .ddrw
  • .dds
  • .der
  • .des
  • .design
  • .dgc
  • .dit
  • .djvu
  • .dng
  • .doc
  • .doc
  • .docm
  • .docx
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .drf
  • .drw
  • .ds4
  • .dsf
  • .dst
  • .dtd
  • .dwfx
  • .dwg
  • .dxb
  • .dxf
  • .dxg
  • .edb
  • .eml
  • .eps
  • .erbsql
  • .erf
  • .ewd
  • .exf
  • .fdb
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fla
  • .flac
  • .flf
  • .flv
  • .flv
  • .flvv
  • .fpx
  • .fxg
  • .gif
  • .gofin
  • .gray
  • .grey
  • .groups
  • .gry
  • .gzip
  • .h
  • .hbk
  • .hdd
  • .hpp
  • .html
  • .html
  • .ibd
  • .ibz
  • .idx
  • .iif
  • .iiq
  • .incpas
  • .indd
  • .java
  • .java
  • .jnt
  • .jpe
  • .jpeg
  • .jpeg
  • .jpg
  • .js
  • .js
  • .kc2
  • .kdbx
  • .kdc
  • .key
  • .kpdx
  • .kwm
  • .laccdb
  • .ldf
  • .lit
  • .lua
  • .m
  • .m2ts
  • .m3u
  • .m4p
  • .m4v
  • .max
  • .mbx
  • .md
  • .mdb
  • .mdc
  • .mdf
  • .mef
  • .mfw
  • .mid
  • .mkv
  • .mlb
  • .mmw
  • .mny
  • .mos
  • .mov
  • .mov
  • .mp3
  • .mp4
  • .mp4
  • .mpeg
  • .mpg
  • .mpg
  • .mrw
  • .msg
  • .myd
  • .nd
  • .ndd
  • .ndf
  • .nef
  • .nk2
  • .nop
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsd
  • .nsf
  • .nsg
  • .nsh
  • .ntx
  • .nvram
  • .nwb
  • .nx2
  • .nxl
  • .nyf
  • .oab
  • .ob
  • .obj
  • .odb
  • .odc
  • .odf
  • .odg
  • .odm
  • .odp
  • .odp
  • .ods
  • .ods
  • .odt
  • .ogg
  • .ogg
  • .ogv
  • .oil
  • .orf
  • .ost
  • .otg
  • .oth
  • .otp
  • .ots
  • .ott
  • .p12
  • .p7b
  • .p7c
  • .pab
  • .pages
  • .pas
  • .pat
  • .pcd
  • .pct
  • .pdb
  • .pdd
  • .pdf
  • .pdf
  • .pef
  • .pem
  • .pem
  • .pfx
  • .php
  • .pif
  • .pl
  • .plc
  • .plus_muhd
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsm
  • .ppsx
  • .ppt
  • .ppt
  • .pptm
  • .pptm
  • .pptx
  • .pptx
  • .prf
  • .ps
  • .psafe3
  • .psd
  • .pst
  • .ptx
  • .pwm
  • .py
  • .py
  • .qba
  • .qbb
  • .qbm
  • .qbr
  • .qbw
  • .qbx
  • .qby
  • .qcow
  • .qcow2
  • .qed
  • .r3d
  • .raf
  • .rar
  • .rar
  • .rat
  • .raw
  • .rb
  • .rdb
  • .rm
  • .rm
  • .rmvb
  • .rtf
  • .rtf
  • .rvt
  • .rw2
  • .rwl
  • .rwz
  • .s3db
  • .safe
  • .sas7bdat
  • .sav
  • .save
  • .say
  • .sd0
  • .sda
  • .sdf
  • .shx
  • .sldm
  • .sldx
  • .sql
  • .sqlite
  • .sqlite3
  • .sqlitedb
  • .sr2
  • .srf
  • .srt
  • .srw
  • .st4
  • .st5
  • .st6
  • .st7
  • .st8
  • .stc
  • .std
  • .sti
  • .stm
  • .stw
  • .stx
  • .svg
  • .swf
  • .swf
  • .sxc
  • .sxd
  • .sxg
  • .sxi
  • .sxm
  • .sxw
  • .tar
  • .tex
  • .tga
  • .thm
  • .tlg
  • .ts
  • .txt
  • .vb
  • .vbox
  • .vdi
  • .vhd
  • .vhdx
  • .vmdk
  • .vmsd
  • .vmx
  • .vmxf
  • .vob
  • .vob
  • .wab
  • .wad
  • .wallet
  • .wav
  • .wav
  • .wb2
  • .wma
  • .wma
  • .wmv
  • .wmv
  • .wpd
  • .wps
  • .x11
  • .x3f
  • .xis
  • .xla
  • .xlam
  • .xlk
  • .xlm
  • .xlr
  • .xls
  • .xls
  • .xlsb3dm
  • .xlsm
  • .xlsx
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .xsd
  • .xsd
  • .xsl
  • .ycbcra
  • .yuv
  • .zip

It encrypts files found in the following folders:

  • %User Profile%\My Documents
  • %User Profile%\Recent
  • %User Profile%\My Pictures
  • %User Profile%\My Music
  • %User Profile%\My Videos
  • %Desktop%
  • %Favorites%
  • %All Users Profile%\Documents
  • %All Users Profile%\Pictures
  • %All Users Profile%\Music
  • %All Users Profile%\Videos
  • %All Users Profile%\Desktop
  • {Fixed Drive Letter}

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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.. %Favorites% is the Favorites folder, where it usually is C:\Documents and Settings\{user name}\Favorites on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Favorites on 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.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on 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.)

It avoids encrypting files found in the following folders:

  • %Malware Path%
  • %Application Data%
  • %AppDataLocal%
  • %ProgramData%
  • C:\Program Files\Common Files

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on 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.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on 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.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.)

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

  • .aes

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.700.08
FIRST VSAPI PATTERN DATE: 05 Oct 2017
VSAPI OPR PATTERN File: 13.701.00
VSAPI OPR PATTERN Date: 06 Oct 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

Identify and terminate files detected as RANSOM_POLSKY.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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
    • AESxWin = ”%Malware Path%\{malware file name}.exe”

Step 5

Delete this registry key

[ 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
    • AESxWin
  • In HKEY_CLASSES_ROOT\Directory\Background\shell
    • AESxWin

Step 6

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:\Program Data\Keyboard

Step 7

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