RANSOM_LOCKY.YCK

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 may be downloaded by other malware/grayware from remote sites.

It deletes itself after execution.

It encrypts files with specific file extensions. It drops files as ransom note.

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.

It may be downloaded by the following malware/grayware from remote sites:

• W2KM_POWMET.SIOH

It may be downloaded from the following remote sites:

• http://{BLOCKED}nmaster.top/support.php?f=3
• http://{BLOCKED}verti.top/support.php?f=3
• http://{BLOCKED}ceramics.com.vn/image/flags/.../1

Installation

This Ransomware drops and executes the following files:

• %Desktop%\ykcol.htm -> ransom note
• %Desktop%\ykcol.bmp -> ransom note, also used as the background image

(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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• Global\{VictimID}
• Local\{VictimID}

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

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

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 0

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

It sets the system's desktop wallpaper to the following image:

Other Details

This Ransomware does the following:

• It avoids infecting system with the following Language:
  Russian
• It deletes shadow copies by executing the following command:
  %System%\vssadmin.exe Delete Shadows /Quiet /All

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It deletes itself after execution.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• .stx
• .svg
• .swf
• .sxc
• .sxd
• .sxg
• .sxi
• .sxm
• .sxw
• .tar
• .tbk
• .tex
• .tga
• .tgz
• .thm
• .tif
• .tiff
• .tlg
• .txt
• .uop
• .uot
• .upk
• .vb
• .vbox
• .vbs
• .vdi
• .vhd
• .vhdx
• .vmdk
• .vmsd
• .vmx
• .vmxf
• .vob
• .wab
• .wad
• .wallet
• .wav
• .wb2
• .wk1
• .wks
• .wma
• .wmv
• .wpd
• .wps
• .x
• .x11
• .x3f
• .xis
• .xlam
• .xlc
• .001
• .002
• .003
• .004
• .005
• .006
• .007
• .008
• .009
• .010
• .011
• .123
• .1cd
• .3dm
• .3ds
• .3fr
• .3g2
• .3gp
• .3pr
• .602
• .7z
• .7zip
• .aac
• .ab4
• .accdb
• .accde
• .accdr
• .accdt
• .ach
• .acr
• .act
• .adb
• .adp
• .ads
• .aes
• .agdl
• .ai
• .aiff
• .ait
• .al
• .aoi
• .apj
• .apk
• .arc
• .arw
• .asc
• .asf
• .asm
• .asp
• .aspx
• .asset
• .asx
• .avi
• .awg
• .back
• .backup
• .backupdb
• .bak
• .bank
• .bat
• .bay
• .bdb
• .bgt
• .bik
• .bin
• .bkp
• .blend
• .bmp
• .bpw
• .brd
• .bsa
• .bz2
• .cdf
• .cdr
• .cdr3
• .cdr4
• .cdr5
• .cdr6
• .cdrw
• .cdx
• .ce1
• .ce2
• .cer
• .cfg
• .cgm
• .cib
• .class
• .cls
• .cmd
• .cmt
• .config
• .contact
• .cpi
• .cpp
• .cr2
• .craw
• .crt
• .crw
• .cs
• .csh
• .csl
• .csr
• .css
• .csv
• .d3dbsp
• .dac
• .das
• .dat
• .db
• .db3
• .db_journal
• .dbf
• .dbx
• .dc2
• .dch
• .dcr
• .dcs
• .ddd
• .ddoc
• .ddrw
• .dds
• .der
• .des
• .design
• .dgc
• .dif
• .dip
• .dit
• .djv
• .djvu
• .dng
• .doc
• .docb
• .docm
• .docx
• .dot
• .dotm
• .dotx
• .drf
• .drw
• .dtd
• .dwg
• .dxb
• .dxf
• .dxg
• .edb
• .eml
• .eps
• .erbsql
• .erf
• .exf
• .fdb
• .ffd
• .fff
• .fh
• .fhd
• .fla
• .flac
• .flf
• .flv
• .flvv
• .forge
• .fpx
• .frm
• .fxg
• .gif
• .gpg
• .gray
• .grey
• .groups
• .gry
• .gz
• .hbk
• .hdd
• .hpp
• .html
• .hwp
• .i
• .ibank
• .ibd
• .ibz
• .idx
• .iif
• .iiq
• .incpas
• .indd
• .iwi
• .j
• .jar
• .java
• .jnt
• .jpe
• .jpeg
• .jpg
• .js
• .kc2
• .kdbx
• .kdc
• .key
• .kpdx
• .kwm
• .l
• .la
• .laccdb
• .lay
• .lay6
• .lbf
• .ldf
• .lit
• .litemod
• .litesql
• .log
• .ltx
• .lua
• .m
• .m2ts
• .m3u
• .m4a
• .m4p
• .m4u
• .m4v
• .mapimail
• .max
• .mbx
• .md
• .mdb
• .mdc
• .mdf
• .mef
• .mfw
• .mid
• .mkv
• .mlb
• .mml
• .mmw
• .mny
• .moneywell
• .mos
• .mov
• .mp3
• .mp4
• .mpeg
• .mpg
• .mrw
• .ms11
• .ms11 (security copy)
• .msg
• .myd
• .myi
• .n64
• .nd
• .ndd
• .ndf
• .nef
• .nk2
• .nop
• .nrw
• .ns2
• .ns3
• .ns4
• .nsd
• .nsf
• .nsg
• .nsh
• .nvram
• .nwb
• .nx2
• .nxl
• .nyf
• .oab
• .obj
• .odb
• .odc
• .odf
• .odg
• .odm
• .odp
• .ods
• .odt
• .ogg
• .oil
• .onetoc2
• .orf
• .ost
• .otg
• .oth
• .otp
• .ots
• .ott
• .p12
• .p7b
• .p7c
• .pab
• .pages
• .paq
• .pas
• .pat
• .pcd
• .pct
• .pdb
• .pdd
• .pdf
• .pef
• .pem
• .pfx
• .php
• .pif
• .pl
• .plc
• .plus_muhd
• .png
• .pot
• .potm
• .potx
• .ppam
• .pps
• .ppsm
• .ppsx
• .ppt
• .pptm
• .pptx
• .prf
• .ps
• .psafe3
• .psd
• .pspimage
• .pst
• .ptx
• .pwm
• .py
• .qba
• .qbb
• .qbm
• .qbr
• .qbw
• .qbx
• .qby
• .qcow
• .qcow2
• .qed
• .r3d
• .raf
• .rar
• .rat
• .raw
• .rb
• .rdb
• .re4
• .rm
• .rtf
• .rvt
• .rw2
• .rwl
• .rwz
• .s3db
• .safe
• .sas7bdat
• .sav
• .save
• .say
• .sch
• .sd0
• .sda
• .sdf
• .sh
• .sldm
• .sldx
• .slk
• .sql
• .sqlite
• .sqlite3
• .sqlitedb
• .sr2
• .srf
• .srt
• .srw
• .st4
• .st5
• .st6
• .st7
• .st8
• .stc
• .std
• .sti
• .stm
• .stw
• .xlk
• .xlm
• .xlr
• .xls
• .xlsb
• .xlsm
• .xlsx
• .xlt
• .xltm
• .xltx
• .xlw
• .xml
• .y
• .ycbcra
• .yuv
• .zip

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

• _Locky_recover_instructions.txt
• _Locky_recover_instructions.bmp
• System Volume Information
• _HELP_instructions.html
• _HELP_instructions.bmp
• _HELP_instructions.txt
• Program Files (x86)
• Application Data
• Program Files
• $Recycle Bin
• thumbs.db
• AppData
• Windows
• winnt
• Boot
• temp
• tmp

It renames encrypted files using the following names:

• {first 8 characters of ID}--{next 4 characters of ID}--{last 4 characters of ID}--{8 hex characters}--{12 hex characters}.ykcol

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

• {folders containing encrypted files}\ykcol-{4 random characters}.htm

NOTES:

This ransomware opens the dropped %User Profile%\yckol.htm which contains the following ransom note: