Ransom_CRYPTGO.AJKS

April 17, 2018
 Analysis by: Wilbert Vidal
 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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 drops files as ransom note.

  TECHNICAL DETAILS

File Size:

1,824,768 bytes

Memory Resident:

No

Initial Samples Received Date:

12 Apr 2018

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 the following component file(s):

  • %User Temp%\Data\Tor\geoip
  • %User Temp%\Data\Tor\geoip6
  • %User Temp%\Tor\libeay32.dll
  • %User Temp%\Tor\libevent-2-0-5.dll
  • %User Temp%\Tor\libevent_core-2-0-5.dll
  • %User Temp%\Tor\libevent_extra-2-0-5.dll
  • %User Temp%\Tor\libgcc_s_sjlj-1.dll
  • %User Temp%\Tor\libssp-0.dll
  • %User Temp%\Tor\ssleay32.dll
  • %User Temp%\Tor\tor-gencert.exe
  • %User Temp%\Tor\tor.exe
  • %User Temp%\Tor\zlib1.dll
  • %Application Data%\tor\lock
  • %Application Data%\tor\state.tmp
  • %Application Data%\tor\unverified-microdesc-consensus.tmp
  • %Application Data%\tor\cached-certs.tmp
  • %Application Data%\tor\cached-microdesc-consensus.tmp
  • %Application Data%\tor\cached-microdescs.new
  • %Application Data%\tor\cached-microdescs.tmp
  • %Application Data%\tor\cached-microdescs.new.tmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.. %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.)

It creates the following folders:

  • %Application Data%\Tor
  • %User Temp%\Tor
  • %User Temp%\Data
  • %User Temp%\Data\Tor

(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.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

Download Routine

This Ransomware connects to the following URL(s) to download its component file(s):

  • www.torproject.org

Other Details

This Ransomware connects to the following URL(s) to check for an Internet connection:

  • www.download.windowsupdate.com

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

  • http://{BLOCKED}gx6af7j.o{BLOCKED}n:80/cross/info.php

It does the following:

  • It copies the encrypted files with their real filenames to:
    • %User Temp%

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • xlsx
  • docx
  • pptx
  • aspx
  • html
  • java
  • jpeg
  • agdl
  • back
  • bank
  • cdr3
  • cdr4
  • cdr5
  • cdr6
  • cdrw
  • craw
  • php5
  • ddoc
  • ddrw
  • djvu
  • docm
  • dotm
  • dotx
  • flac
  • gray
  • grey
  • indd
  • kdbx
  • kpdx
  • potm
  • potx
  • ppam
  • ppsm
  • ppsx
  • pptm
  • s3dbs
  • sldm
  • sldx
  • xlam
  • xlsb
  • xlsm
  • xltm
  • xltx
  • asmx
  • Conf
  • jin
  • xls
  • pdf
  • ppt
  • txt
  • dwg
  • bak
  • bkf
  • pst
  • dbx
  • zip
  • rar
  • mdb
  • asp
  • htm
  • dbf
  • 3dm
  • 3ds
  • 3fr
  • jar
  • 3g2
  • xml
  • png
  • tif
  • 3gp
  • jpe
  • jpg
  • jsp
  • php
  • 3pr
  • ab4
  • ach
  • kbx
  • acr
  • act
  • adb
  • ads
  • ait
  • apj
  • arw
  • asf
  • asm
  • asx
  • avi
  • awg
  • pbl
  • bay
  • bdb
  • bgt
  • bik
  • bkp
  • bpw
  • cdf
  • cdr
  • cdx
  • ce1
  • ce2
  • cer
  • cfp
  • cgm
  • cib
  • cls
  • cmt
  • cpi
  • cpp
  • cr2
  • crt
  • crw
  • csh
  • csl
  • tib
  • csv
  • dac
  • db3
  • dc2
  • dcr
  • dcs
  • ddd
  • dds
  • der
  • des
  • dgc
  • dng
  • dot
  • drf
  • drw
  • dtd
  • dxb
  • dxf
  • dxg
  • eml
  • eps
  • erf
  • exf
  • fdb
  • ffd
  • fff
  • fmb
  • fhd
  • fla
  • flv
  • fpx
  • fxg
  • gry
  • hbk
  • ibd
  • ibz
  • idx
  • iif
  • iiq
  • kc2
  • kdc
  • key
  • lua
  • m4v
  • max
  • mdc
  • mdf
  • mef
  • mfw
  • mmw
  • mos
  • mov
  • mp3
  • mp4
  • mpg
  • mrw
  • msg
  • myd
  • 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
  • pas
  • pat
  • pcd
  • pct
  • pdb
  • pdd
  • pef
  • pem
  • pfx
  • plc
  • pot
  • pps
  • prf
  • psd
  • ptx
  • qbaq
  • qbb
  • qbm
  • qbr
  • qbw
  • qbx
  • qby
  • q3d
  • qaf
  • qat
  • qaw
  • qdb
  • qtf
  • qw2
  • qwl
  • qwz
  • say
  • sd0
  • sda
  • sdf
  • sql
  • sr2
  • srf
  • srt
  • srw
  • st4
  • st5
  • st6
  • st7
  • st8
  • std
  • sti
  • stw
  • stx
  • svg
  • swf
  • sxc
  • sxd
  • sxg
  • sxi
  • sxn
  • sxw
  • tex
  • thm
  • tlg
  • vob
  • war
  • wav
  • wb2
  • wmv
  • wpd
  • wps
  • x11
  • x3f
  • xis
  • xlam
  • xlk
  • xlm
  • xlr
  • xls
  • xlw
  • yuv

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

  • WIN
  • REC

It renames encrypted files using the following names:

  • {random filename}.encrypted

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

  • %Desktop%\READ_TO_DECRYPT.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:

14.186.08

FIRST VSAPI PATTERN DATE:

12 Apr 2018

VSAPI OPR PATTERN File:

14.187.00

VSAPI OPR PATTERN Date:

13 Apr 2018

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.  
  • %Application Data%\Tor
  • %User Temp%\Tor
  • %User Temp%\Data
  • %User Temp%\Data\Tor

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.
  • %Desktop%\READ_TO_DECRYPT.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom_CRYPTGO.AJKS. 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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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