RANSOM_LOCKY.BYX
Ransom:Win32/Locky (Microsoft); Ransom.Locky (Malwarebytes); Win32/Filecoder.Locky.A (ESET-NOD32); Trojan/Win32.Locky (AhnLab-V3)
Windows

Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
Dropped by other malware
This Trojan may be downloaded from remote sites by other malware.
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.
TECHNICAL DETAILS
173,056 bytes
EXE
No
02 Apr 2016
Drops files, Encrypts files, Connects to URLs/IPs, Steals information
Arrival Details
This Trojan may be downloaded from remote site(s) by the following malware:
- JS_LOCKY.SSU
Installation
This Trojan drops the following component file(s):
- %Desktop%\_Locky_recover_instructions.txt - ransom note
- %Desktop%\_Locky_recover_instructions.bmp - image used as wallpaper
- {Folders containing encrypted files}\_Locky_recover_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.)
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\Locky
It adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Locky
id = "{unique ID per victim}"
HKEY_CURRENT_USER\Software\Locky
pubkey = "{publick key}"
HKEY_CURRENT_USER\Software\Locky
paytext = "{ransom note}"
HKEY_CURRENT_USER\Software\Locky
completed = "1"
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:
- http://{BLOCKED}.{BLOCKED}.109.205/main.php
- http://{BLOCKED}.{BLOCKED}.27.52/main.php
- http://{BLOCKED}.{BLOCKED}.107.8/main.php
- http://{BLOCKED}.{BLOCKED}.231.116/main.php
- http://{BLOCKED}.{BLOCKED}.107.10/main.php
- http://{BLOCKED}.{BLOCKED}.108.39/main.php
- http://{BLOCKED}.{BLOCKED}.181.122/main.php
- http://{pseudo-random domain}/main.php
It encrypts files with the following extensions:
- .cs
- .brd
- .sch
- .dch
- .dip
- .pl
- .vbs
- .vb
- .js
- .h
- .asm
- .pas
- .cpp
- .c
- .php
- .ldf
- .mdf
- .ibd
- .MYI
- .MYD
- .frm
- .odb
- .dbf
- .db
- .mdb
- .sql
- .SQLITEDB
- .SQLITE3
- .one
- .toc2
- .asc
- .lay6
- .lay
- .ms11 (Security copy)
- .ms11
- .sldm
- .sldx
- .ppsm
- .ppsx
- .ppam
- .docb
- .mml
- .sxm
- .otg
- .odg
- .uop
- .potx
- .potm
- .pptx
- .pptm
- .std
- .sxd
- .pot
- .pps
- .sti
- .sxi
- .otp
- .odp
- .wb2
- .123
- .wks
- .wk1
- .xltx
- .xltm
- .xlsx
- .xlsm
- .xlsb
- .slk
- .xlw
- .xlt
- .xlm
- .xlc
- .dif
- .stc
- .sxc
- .ots
- .ods
- .hwp
- .602
- .dotm
- .dotx
- .docm
- .docx
- .DOT
- .3dm
- .max
- .3ds
- .xml
- .txt
- .CSV
- .uot
- .RTF
- .XLS
- .PPT
- .stw
- .sxw
- .ott
- .odt
- .DOC
- .pem
- .p12
- .csr
- .crt
- .key
- wallet.dat
- .m4u
- .m3u
- .mid
- .wma
- .flv
- .3g2
- .mkv
- .3gp
- .mp4
- .mov
- .avi
- .asf
- .mpeg
- .vob
- .mpg
- .wmv
- .fla
- .swf
- .wav
- .mp3
- .qcow2
- .vdi
- .vmdk
- .vmx
- .gpg
- .aes
- .ARC
- .PAQ
- .tar
- .bz2
- .tbk
- .bak
- .tar
- .tgz
- .gz
- .7z
- .rar
- .zip
- .djv
- .djvu
- .svg
- .bmp
- .png
- .gif
- .raw
- .cgm
- .jpeg
- .jpg
- .tif
- .tiff
- .NEF
- .psd
- .cmd
- .bat
- .sh
- .class
- .jar
- .java
- .rb
- .asp
It does the following:
- It prevents to encrypt files containing any of the strings in its full pathname:
- tmp
- winnt
- Application Data
- AppData
- Program Files (x86)
- Program Files
- temp
- thumbs.db
- $Recycle.Bin
- System Volume Information
- Boot
- Windows
- It encrypts files on all fixed drives, removable drives and RAM disk drives.
- It executes the following command to delete shadow copies:
vssadmin.exe Delete Shadows /All /Quiet
- After encryption of files, it uninstalls itself by deleting its autorun registry and its copy.
- 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
It gathers the following information and reports it to its servers:
- Operating System version
- 32 or 64 bit version
- Service Pack
- System Language
NOTES:
This malware sets the system's desktop wallpaper to the following image:

It opens the dropped _Locky_recover_instructions.txt file, which contains the ransom note:

SOLUTION
9.800
12.404.05
15 Mar 2016
12.405.00
17 Mar 2016
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
Restart in Safe Mode
Step 4
Delete this registry value
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\Control Panel\Desktop
- Wallpaper = "%Desktop%\_Locky_recover_instructions.bmp"
- Wallpaper = "%Desktop%\_Locky_recover_instructions.bmp"
Step 5
Delete this registry key
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
- Locky
- Locky
Step 6
Search and delete these files
- %Desktop%\_Locky_recover_instructions.txt
- %Desktop%\_Locky_recover_instructions.bmp
- {Folders containing encrypted files}\_Locky_recover_instructions.txt
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_LOCKY.BYX. 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 8
Restore encrypted files from backup.
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