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

Win32/Filecoder.WannaCryptor.B [Threat Variant Name]

Category trojan
Size 237568 B
Detection created Apr 06, 2017
Detection database version 15214
Aliases Ransom:Win32/WannaCrypt!rfn (Microsoft)
  Ransom.Wannacry (Symantec)
  Trojan.Encoder.10609 (Dr.Web)
Short description

Win32/Filecoder.WannaCryptor.B is a trojan that encrypts files on local drives. To decrypt files, the user is asked to send information/certain amount of money via the Bitcoin payment service.

Installation

When executed, the trojan creates the following files:

  • %malwarefolder%\­­%number%.pkey
  • %malwarefolder%\­­%number%.dkey
  • %malwarefolder%\­­%number%.ekey
  • %malwarefolder%\­­­%number%.res
  • %malwarefolder%\­­b.wry
  • %malwarefolder%\­­c.wry
  • %malwarefolder%\­­m.wry
  • %malwarefolder%\­­r.wry
  • %malwarefolder%\­­t.wry
  • %malwarefolder%\­­u.wry
  • %malwarefolder%\­­f.wry
  • %malwarefolder%\­­n.wry
  • %malwarefolder%\­­TaskHost\­Data\­Tor\­geoip
  • %malwarefolder%\­­TaskHost\­Data\­Tor\­geoip6
  • %malwarefolder%\­TaskHost\­Tor\­libeay32.dll
  • %malwarefolder%\­TaskHost\­Tor\­libevent-2-0-5.dll
  • %malwarefolder%\­TaskHost\­Tor\­libevent_core-2-0-5.dll
  • %malwarefolder%\­TaskHost\­Tor\­libevent_extra-2-0-5.dll
  • %malwarefolder%\­TaskHost\­Tor\­libgcc_s_sjlj-1.dll
  • %malwarefolder%\­TaskHost\­Tor\­libssp-0.dll
  • %malwarefolder%\­TaskHost\­Tor\­ssleay32.dll
  • %malwarefolder%\­TaskHost\­Tor\­taskhosts.exe
  • %malwarefolder%\­TaskHost\­Tor\­tor.exe
  • %malwarefolder%\­TaskHost\­Tor\­tor-gencert.exe
  • %malwarefolder%\­TaskHost\­Tor\­zlib1.dll
  • %temp%\­hibsys
  • %drive%\­hibsys

A string with variable content is used instead of %number% .


The trojan may set the following Registry entries:

  • [HKEY_CURRENT_USER\­Software\­Microsoft\­Windows\­CurrentVersion\­Run]
    • "Microsoft Update Scheduler" = "%malwarepath% /r %number%"
  • [HKEY_LOCAL_MACHINE\­Software\­Microsoft\­Windows\­CurrentVersion\­Run]
    • "Microsoft Update Scheduler" = "%malwarepath% /r %number%"

This causes the trojan to be executed on every system start.


The following Registry entries are created:

  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­WannaCryptor]
    • "wd" = "%malwarefolder%"
  • [HKEY_CURRENT_USER\­Control Panel\­Desktop\­Wallpaper]
    • "Wallpaper" = "%malwarefolder%\­!WannaCryptor!.bmp"
Payload information

Win32/Filecoder.WannaCryptor.B is a trojan that encrypts files on local drives.


The trojan searches local drives for files with the following file extensions:

  • .123
  • .602
  • .3dm
  • .3ds
  • .3g2
  • .3gp
  • .7z
  • .aes
  • .ai
  • .ARC
  • .asc
  • .asf
  • .asp
  • .avi
  • .backup
  • .bak
  • .bmp
  • .brd
  • .c
  • .cgm
  • .class
  • .cpp
  • .crt
  • .cs
  • .csr
  • .csv
  • .db
  • .dbf
  • .dch
  • .der
  • .dif
  • .dip
  • .doc
  • .docb
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .dwg
  • .edb
  • .eml
  • .fla
  • .flv
  • .frm
  • .gif
  • .gpg
  • .gz
  • .h
  • .hwp
  • .ibd
  • .jar
  • .java
  • .jpeg
  • .jpg
  • .js
  • .jsp
  • .key
  • .lay
  • .lay6
  • .ldf
  • .m3u
  • .m4u
  • .max
  • .mdb
  • .mdf
  • .mid
  • .mkv
  • .mml
  • .mov
  • .mp3
  • .mp4
  • .mpeg
  • .mpg
  • .msg
  • .myd
  • .myi
  • .nef
  • .odb
  • .odg
  • .odp
  • .ods
  • .odt
  • .ost
  • .otg
  • .otp
  • .ots
  • .ott
  • .p12
  • .PAQ
  • .pas
  • .pdf
  • .pem
  • .pfx
  • .php
  • .pl
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .psd
  • .pst
  • .rar
  • .raw
  • .rb
  • .rtf
  • .sch
  • .sh
  • .slk
  • .sln
  • .sql
  • .sqlite3
  • .sqlitedb
  • .stc
  • .std
  • .stw
  • .suo
  • .swf
  • .sxc
  • .sxd
  • .sxm
  • .sxw
  • .tar
  • .tar.bz2
  • .tbk
  • .tgz
  • .tif
  • .tiff
  • .txt
  • .uop
  • .uot
  • .vb
  • .vdi
  • .vmdk
  • .vmx
  • .vob
  • .vsd
  • .vsdx
  • .wav
  • .wb2
  • .wk1
  • .wks
  • .wma
  • .wmv
  • .xlc
  • .xlm
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .zip

It avoids files from the following directories:

  • \­WINDOWS
  • \­Program Files
  • \­Program Files (x86)
  • \­ProgramData

It avoids files with the following filenames:

  • !Please Read Me!.txt
  • !WannaDecryptor!.exe.lnk
  • !WannaCryptor!.bmp

The trojan encrypts the file content.


The RSA, AES encryption algorithm is used.


The extension of the encrypted files is changed to:

  • %filepath%.WCRY

To decrypt files, the user is asked to send information/certain amount of money via the Bitcoin payment service.


Some examples follow.

Other information

When searching the drives, the trojan creates the following file in every folder visited:

  • !WannaDecryptor!.exe.lnk

The file is a shortcut to a following file:

  • %malwarefolder%\­­!WannaDecryptor!.exe

The following file is dropped in the same folder:

  • !Please Read Me!.txt

It contains the following text:

  • Q:  What's wrong with my files?
  • A:  Ooops, your important files are encrypted. It means you will not be able to access them anymore until they are decrypted.
  • If you follow our instructions we guarantee that you can decrypt all your files quickly and safely!
  • Let's start decrypting!
  • Q:  What do I do?
  • A:  First, you need to pay service fees for the decryption.
  • Please send $200 worth of bitcoin to this bitcoin address: 1QAc9S5EmycqjzzWDc1yiWzr9jJLC8sLiY
  • Next, please find the decrypt software on your desktop, an executable file named "!WannaDecryptor!.exe".
  • If it does not exsit, download the software from the address below. (You may need to disable your antivirus for a while.)
  • https://www.dropbox.com/s/c1gn29iy8erh1ks/m.rar?dl=1
  • rar password: wcry123
  • Run and follow the instructions!

The trojan may delete the following files:

  • %temp%\­hibsys
  • %drive%\­hibsys

The trojan executes the following commands:

  • cmd.exe /c start /b !WannaDecryptor!.exe c
  • cmd.exe /c start /b !WannaDecryptor!.exe v
  • cmd.exe /c start /b vssadmin.exe Delete Shadows /All /Quiet
  • %malwarefolder%\­TaskHost\­Tor\­taskhost.exe

The trojan contains a list of (2) URLs.


It tries to download a file from the addresses. The HTTPS protocol is used in the communication.

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