TROJ_CRYPLOCK.V

 Analysis by: Vincent Martin Hermosura

 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:

Downloaded from the Internet, Dropped by other malware


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 connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

418,816 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Oct 2014

Payload:

Encrypts files, Steals information

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 copies of itself into the affected system:

  • %All Users Profile%\Application Data\{random characters 2}\01000000
  • %Windows%\{random characters 1}.exe

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

It adds the following processes:

  • explorer.exe

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters 3} = "%Windows%\{random characters 1}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{random characters 4}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random characters 4}
01000000 = "{binary copy of itself}"

HKEY_CURRENT_USER\Software\{random characters 4}
02000000 = "%Windows%\{random characters 1}.exe"

HKEY_CURRENT_USER\Software\{random characters 4}
00000000 = "{hex values}"

Information Theft

This Trojan gathers the following data:

  • Machine GUID
  • Computer name

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}ofnigeria.net:443

However, as of this writing, the said sites are inaccessible.

NOTES:

This Trojan connects to the URL above to download the key used in encrypting the files.

It encrypts the following files and appends "encrypted" to them:

  • 3ds
  • 3fr
  • 3pr
  • 7z
  • ab4
  • ac2
  • accdb
  • accde
  • accdr
  • accdt
  • acr
  • adb
  • agd1
  • ai
  • ait
  • al
  • apj
  • arw
  • asm
  • asp
  • awg
  • backup
  • backupdb
  • bak
  • bdb
  • bgt
  • bik
  • bkp
  • blend
  • bpw
  • cdf
  • cdr
  • cdr3
  • cdr4
  • cdr5
  • cdr6
  • cdrw
  • cdx
  • ce1
  • ce2
  • cer
  • cfp
  • cgm
  • cib
  • cls
  • cmt
  • cpi
  • cpp
  • cr2
  • craw
  • crt
  • crw
  • csh
  • csl
  • css
  • csv
  • dac
  • db
  • db-journal
  • db3
  • dbf
  • dc2
  • dcr
  • dcs
  • ddd
  • ddoc
  • ddrw
  • der
  • design
  • dgc
  • djvu
  • dng
  • doc
  • docm
  • docx
  • dot
  • dotm
  • dotx
  • drf
  • drw
  • dwg
  • dxb
  • erbsql
  • erf
  • exf
  • fdb
  • ffd
  • fff
  • fh
  • fhd
  • fpx
  • fxg
  • gray
  • grey
  • gry
  • hbk
  • hpp
  • ibank
  • ibd
  • ibz
  • idx
  • iiq
  • incpas
  • jpeg
  • jpg
  • js
  • kc2
  • kdbx
  • kdc
  • kpdx
  • lua
  • mdb
  • mdc
  • mef
  • mfw
  • mmw
  • moneywell
  • mos
  • mpg
  • mrw
  • myd
  • ndd
  • nef
  • nop
  • nrw
  • ns2
  • ns3
  • ns4
  • nsd
  • nsf
  • nsg
  • nsh
  • nwb
  • nx1
  • nx2
  • nyf
  • odb
  • odf
  • odg
  • odm
  • odp
  • ods
  • odt
  • orf
  • otg
  • oth
  • otp
  • ots
  • ott
  • p12
  • p7b
  • p7c
  • pat
  • pcd
  • pdf
  • pef
  • pem
  • pfx
  • php
  • pl
  • pot
  • potm
  • potx
  • ppam
  • pps
  • ppsm
  • ppsx
  • ppt
  • pptm
  • pptx
  • ps
  • psafe3
  • psd
  • ptx
  • py
  • ra2
  • raf
  • rar
  • raw
  • rdb
  • rtf
  • rw2
  • rwl
  • rwz
  • s3db
  • sas7bdat
  • sav
  • sd0
  • sd1
  • sda
  • sdf
  • sldm
  • sldx
  • sql
  • sqlite
  • sqlite3
  • sqlitedb
  • sr2
  • srf
  • srw
  • st4
  • st5
  • st6
  • st7
  • st8
  • stc
  • std
  • sti
  • stw
  • stx
  • sxc
  • sxd
  • sxg
  • sxi
  • sxm
  • sxw
  • txt
  • wb2
  • x3f
  • xla
  • xlam
  • xll
  • xlm
  • xls
  • xlsb
  • xlsm
  • xlsx
  • xlt
  • xltm
  • xltx
  • xlw
  • xml
  • ycbcra
  • zip

After successfully encrypting user's files, it drops the ransom note DECRYPT_INSTRUCTIONS.html.

  SOLUTION

Minimum Scan Engine:

9.700

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

Scan your computer with your Trend Micro product and note files detected as TROJ_CRYPLOCK.V

Step 4

Restart in Safe Mode

[ Learn More ]

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
    • {random characters 4}

Step 6

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
    • {random characters 3} = "%Windows%\{random characters 1}.exe"
  • In HKEY_CURRENT_USER\Software\{random characters 4}
    • 01000000 = {binary copy of itself}
  • In HKEY_CURRENT_USER\Software\{random characters 4}
    • 02000000 = %Windows%\{random characters 1}.exe
  • In HKEY_CURRENT_USER\Software\{random characters 4}
    • 00000000 = {hex values}

Step 7

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.
  • DECRYPT_INSTRUCTIONS.html

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPLOCK.V. 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 9

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • %All Users Profile%\Application Data\{random characters 2}\01000000
  • %Windows%\{random characters 1}.exe
  • HKEY_CURRENT_USER\Software\{random characters 4}


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