RANSOM_LOCKY.DLDRK

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 does not have any propagation routine.

It does not have any backdoor routine.

It modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information. It gathers information and reports it to its servers.

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:

• %User Temp%\svchost.exe

(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.)

It drops the following component file(s):

• %Desktop%\_HELP_instructions.txt - ransom note
• %Desktop%\_HELP_instructions.bmp - image used as wallpaper
• {folders containing encrypted files}\_HELP_instructions.txt - ransom note

(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.)

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
Locky = "%User Temp%\svchost.exe"

Other System Modifications

This Trojan modifies the following file(s):

• It renames the encrypted files to {unique ID per victim}{identifier}.locky

It adds the following registry keys:

HKEY_CURRENT_USER\Software\{random characters}

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Desktop%\_HELP_instructions.bmp"

HKEY_CURRENT_USER\Software\{random characters}
{random 1} = "{hex values}"

HKEY_CURRENT_USER\Software\{random characters}
{random 2} = "{hex values}"

HKEY_CURRENT_USER\Software\{random characters}
{random 3} = "{hex values}"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

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

• {Domain Generated Algorithm}.{ru, info, biz, click, su, work, pl, org, pw, xyz}
• http://{BLOCKED}.{BLOCKED}.76.18/submit.php
• http://{BLOCKED}.{BLOCKED}.170.249/submit.php
• http://{BLOCKED}.{BLOCKED}.35.128/submit.php

It encrypts files with the following extensions:

• .001
• .002
• .003
• .004
• .005
• .006
• .007
• .008
• .009
• .010
• .011
• .123
• .3dm
• .3ds
• .3g2
• .3gp
• .602
• .7z
• .ARC
• .CSV
• .DOC
• .DOT
• .MYD
• .MYI
• .NEF
• .PAQ
• .PPT
• .RTF
• .SQLITE3
• .SQLITEDB
• .XLS
• .aes
• .asc
• .asf
• .asm
• .asp
• .avi
• .bak
• .bat
• .bmp
• .brd
• .c
• .cgm
• .class
• .cmd
• .cpp
• .crt
• .cs
• .csr
• .db
• .dbf
• .dch
• .dif
• .dip
• .djv
• .djvu
• .docb
• .docm
• .docx
• .dotm
• .dotx
• .fla
• .flv
• .frm
• .gif
• .gpg
• .gz
• .h
• .hwp
• .ibd
• .jar
• .java
• .jpeg
• .jpg
• .js
• .key
• .lay
• .lay6
• .ldf
• .m3u
• .m4u
• .max
• .mdb
• .mdf
• .mid
• .mkv
• .mml
• .mov
• .mp3
• .mp4
• .mpeg
• .mpg
• .ms11
• .ms11 (Security copy)
• .n64
• .odb
• .odg
• .odp
• .ods
• .odt
• .onetoc2
• .otg
• .otp
• .ots
• .ott
• .p12
• .pas
• .pdf
• .pem
• .php
• .pl
• .png
• .pot
• .potm
• .potx
• .ppam
• .pps
• .ppsm
• .ppsx
• .pptm
• .pptx
• .psd
• .pst
• .qcow2
• .rar
• .raw
• .rb
• .sch
• .sh
• .sldm
• .sldx
• .slk
• .sql
• .stc
• .std
• .sti
• .stw
• .svg
• .swf
• .sxc
• .sxd
• .sxi
• .sxm
• .sxw
• .tar
• .tar.bz2
• .tbk
• .tgz
• .tif
• .tiff
• .txt
• .uop
• .uot
• .vb
• .vbs
• .vdi
• .vmdk
• .vmx
• .vob
• .wav
• .wb2
• .wk1
• .wks
• .wma
• .wmv
• .xlc
• .xlm
• .xlsb
• .xlsm
• .xlsx
• .xlt
• .xltm
• .xltx
• .xlw
• .xml
• .zip
• wallet.dat

It does the following:

• It prevents to encrypt files containing any of the strings in its full pathname:
  • AppData
  • Application Data
  • Program Files
  • Program Files (x86)
  • $Recycle.Bin
  • System Volume Information
  • Windows
  • winnt
  • BOOT
  • temp
  • thumbs.db
  • _HELP_instructions.bmp
  • _HELP_instructions.txt
  • _Locky_recover_instructions.bmp
  • _Locky_recover_instructions.txt
• It encrypts files on all fixed drives, removable drives, RAM disk drives and network resources.
• It executes the following command to delete shadow copies:

  vssadmin.exe Delete Shadows /All /Quiet

• It sends information to its C&C using the following parameters:
  • id - generated victim ID
  • act - has 3 control commands

    where the control commands can be any of the following:

    • stats - Statistics of encryption and paths of encrypted files
    • getkey - Request RSA public key from C&C
    • gettext - Request ransomware text in specific language

• After encryption of files, it uninstalls itself by deleting its autorun registry and its copy.

It gathers the following information and reports it to its servers:

• Operating System version
• OS Architecture (if 64 bit version)
• Service Pack
• System Language
• Victim ID

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.