Win32/Filecoder.CryptoWall [Threat Name] go to Threat

Win32/Filecoder.CryptoWall.F [Threat Variant Name]

Category trojan
Size 196608 B
Detection created Nov 09, 2015
Detection database version 12539
Aliases Trojan-Ransom.Win32.Cryptodef.acie (Kaspersky)
  Ransom:Win32/Crowti.A (Microsoft)
  Trojan.Encoder.3453 (Dr.Web)
Short description

Win32/Filecoder.CryptoWall.F is a trojan that encrypts files on fixed, removable and network drives. To decrypt files the user is requested to comply with given conditions in exchange for a password/instructions.

Installation

When executed the trojan copies itself in the following locations:

  • %appdata%\­%variable1%\­%variable2%.exe

A string with variable content is used instead of %variable1-2% .


In order to be executed on every system start, the trojan sets the following Registry entries:

  • [HKEY_CURRENT_USER\­Software\­Microsoft\­Windows\­CurrentVersion\­Run]
    • "%variable1%" = "%appdata%\­%variable1%\­%variable2%.exe"

After the installation is complete, the trojan deletes the original executable file.

Payload information

Win32/Filecoder.CryptoWall.F is a trojan that encrypts files on fixed, removable and network drives.


The trojan acquires data and commands from a remote computer or the Internet.


The trojan contains a list of (6) URLs. The HTTP protocol is used.


The trojan searches local and network drives for files with one of the following extensions:

  • .3dm
  • .3ds
  • .3gp
  • .7z
  • .ab4
  • .accdb
  • .accde
  • .accdp
  • .accdr
  • .accdt
  • .accdu
  • .ach
  • .acr
  • .act
  • .adb
  • .ads
  • .agdl
  • .ai
  • .ait
  • .al
  • .apj
  • .arw
  • .asf
  • .asm
  • .asp
  • .asx
  • .avi
  • .awg
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bank
  • .bay
  • .bdb
  • .bgt
  • .bik
  • .bkf
  • .bkp
  • .blend
  • .bpw
  • .c
  • .cdb
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfp
  • .cgm
  • .cib
  • .class
  • .cls
  • .cmt
  • .cnv
  • .cpi
  • .cpp
  • .cr2
  • .craw
  • .crt
  • .crw
  • .cs
  • .csh
  • .csl
  • .csv
  • .dac
  • .db
  • .db3
  • .dbf
  • .dbr
  • .dbs
  • .dc2
  • .dcr
  • .dcs
  • .dcx
  • .ddd
  • .ddoc
  • .ddrw
  • .dds
  • .der
  • .des
  • .design
  • .dgc
  • .djvu
  • .dng
  • .doc
  • .docb
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .drf
  • .drw
  • .dtd
  • .dwg
  • .dxb
  • .dxf
  • .dxg
  • .ebd
  • .edb
  • .eml
  • .eps
  • .erbsql
  • .erf
  • .exf
  • .fdb
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fla
  • .flac
  • .flv
  • .fm
  • .fp7
  • .fpx
  • .fxg
  • .gdb
  • .gray
  • .grey
  • .grw
  • .gry
  • .h
  • .hbk
  • .hpp
  • .ib
  • .ibank
  • .ibd
  • .ibz
  • .idx
  • .iif
  • .iiq
  • .indd
  • .itdb
  • .java
  • .jgf
  • .jpe
  • .jpeg
  • .jpg
  • .kc2
  • .kdbx
  • .kdc
  • .key
  • .kpdx
  • .laccdb
  • .lua
  • .m
  • .m4v
  • .m4v
  • .maf
  • .mam
  • .maq
  • .mar
  • .maw
  • .max
  • .mdb
  • .mdc
  • .mde
  • .mdf
  • .mdt
  • .mef
  • .mfw
  • .mmw
  • .mos
  • .mov
  • .mp3
  • .mp4
  • .mpg
  • .mpp
  • .mrw
  • .msmessagestore
  • .mso
  • .myd
  • .nd
  • .ndd
  • .nef
  • .nk2
  • .nop
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsd
  • .nsf
  • .nsg
  • .nsh
  • .nwb
  • .nx1
  • .nx2
  • .nxl
  • .nyf
  • .obj
  • .odb
  • .odc
  • .odf
  • .odg
  • .odm
  • .odp
  • .ods
  • .odt
  • .oil
  • .one
  • .onepkg
  • .orf
  • .otg
  • .oth
  • .otp
  • .ots
  • .ott
  • .oxps
  • .p12
  • .p7b
  • .p7c
  • .pages
  • .pas
  • .pat
  • .pbo
  • .pcd
  • .pct
  • .pdb
  • .pdd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .pip
  • .pl
  • .plc
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .prf
  • .ps
  • .psafe3
  • .psd
  • .pspimage
  • .ptx
  • .pub
  • .puz
  • .py
  • .qba
  • .qbb
  • .qbm
  • .qbr
  • .qbw
  • .qbx
  • .qby
  • .r3d
  • .raf
  • .rar
  • .rat
  • .raw
  • .rdb
  • .rm
  • .rpmsg
  • .rtf
  • .rw2
  • .rwl
  • .rwz
  • .s3db
  • .say
  • .sd0
  • .sda
  • .sdf
  • .sl2
  • .sldm
  • .sldx
  • .snp
  • .sql
  • .sqlite
  • .sqlitedb
  • .sr2
  • .srf
  • .srt
  • .srw
  • .st4
  • .st5
  • .st6
  • .st7
  • .st8
  • .stc
  • .std
  • .sti
  • .stw
  • .stx
  • .svg
  • .swf
  • .sxc
  • .sxd
  • .sxg
  • .sxi
  • .sxm
  • .sxw
  • .tex
  • .tga
  • .thm
  • .tif
  • .tlg
  • .txt
  • .vob
  • .vsd
  • .vsdx
  • .vsx
  • .vtx
  • .wallet
  • .wav
  • .wb2
  • .wbk
  • .wdb
  • .wll
  • .wmv
  • .wpd
  • .wps
  • .x11
  • .x3f
  • .xis
  • .xla
  • .xlam
  • .xlb
  • .xlc
  • .xlk
  • .xll
  • .xllsx
  • .xlm
  • .xlr
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xpp
  • .xsn
  • .ycbcra
  • .yuv
  • .zip

It avoids those with any of the following strings in their names:

  • decrypt_instruction.html
  • decrypt_instruction.txt
  • decrypt_instruction.url
  • help_decrypt.html
  • help_decrypt.png
  • help_decrypt.txt
  • help_decrypt.url
  • help_your_files.html
  • help_your_files.png
  • help_your_files.txt
  • how_decrypt.html
  • how_decrypt.txt
  • how_decrypt.url
  • iconcache.db
  • thumbs.db

It avoids files which contain any of the following strings in their path:

  • .
  • ..
  • cache
  • cache2
  • default pictures
  • games
  • nvidia
  • packages
  • program files
  • program files (x86)
  • sample music
  • sample pictures
  • sample videos
  • temp
  • temporary internet files
  • user account pictures
  • webcache
  • windows

It avoids files with the following extensions:

  • .application
  • .bat
  • .cmd
  • .com
  • .cpl
  • .dll
  • .exe
  • .gadget
  • .hta
  • .msc
  • .msi
  • .msp
  • .pif
  • .scf
  • .scr
  • .sys

The trojan encrypts the file content.


The AES, RSA encryption algorithm is used.


The name of the encrypted file is changed to:

  • %variable3%.%variable4%

A string with variable content is used instead of %variable3-4% .


The following file is dropped into the %currentfolder%, %driveroot% folder:

  • HELP_YOUR_FILES.PNG

The following files are dropped into the %desktop%, %startup% folder:

  • HELP_YOUR_FILES.HTML
  • HELP_YOUR_FILES.PNG
  • HELP_YOUR_FILES.TXT

The files are then executed.


To decrypt files the user is requested to comply with given conditions in exchange for a password/instructions.


When files encryption is finished, the trojan removes itself from the computer.

Other information

The trojan creates and runs a new thread with its own program code within the following processes:

  • explorer.exe
  • svchost.exe

The trojan executes the following command:

  • vssadmin.exe Delete Shadows /All /Quiet

The trojan may set the following Registry entries:

  • [HKEY_LOCAL_MACHINE\­­SOFTWARE\­­Microsoft\­­Windows NT\­­CurrentVersion\­­SystemRestore]
    • "DisableSR" = 1

The trojan keeps various information in the following files:

  • %appdata%\­%variable5%

The trojan can download and execute a file from the Internet.


The file is stored in the following location:

  • %temp%\­%variable6%

The file is then executed.


A string with variable content is used instead of %variable5-6% .

Please enable Javascript to ensure correct displaying of this content and refresh this page.