Analysis by: Noel Anthony Llimos

ALIASES:

Gen:Heur.ZCrypt.1 (Bitdefender), Trojan-Ransom.Win32.Gen.fyt (Kaspersky), Ransom:Win32/Genasom (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

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 drops files as ransom note.

  TECHNICAL DETAILS

File Size: 801280 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 20 Nov 2017
Payload: Displays message/message boxes

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.

Autostart Technique

This Ransomware drops the following files:

  • %User Startup%\WannaSmile.lnk
  • %Application Data%\WannaSmile.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
WannaSmile = %User Temp%\{Executed Malware Filename}.exe

Other Details

This Ransomware encrypts files with the following extensions:

  • .3dm
  • .3ds
  • .3fr
  • .7z
  • .XCODEPROJ
  • .accdb
  • .ai
  • .ai
  • .apk
  • .arw
  • .asm
  • .aspx
  • .avi
  • .bak
  • .bay
  • .bmp
  • .c
  • .cbr
  • .cdr
  • .cgi
  • .class
  • .conf
  • .config
  • .cpp
  • .cr2
  • .crt
  • .crw
  • .cs
  • .db
  • .dbf
  • .dbf
  • .dcr
  • .der
  • .dng
  • .doc
  • .docx
  • .dwg
  • .dxf
  • .dxg
  • .eml
  • .emlx
  • .eps
  • .erf
  • .fla
  • .gif
  • .gz
  • .gz
  • .h
  • .html
  • .indd
  • .iso
  • .jar
  • .java
  • .jnt
  • .jpeg
  • .jpg
  • .js
  • .jsp
  • .kdc
  • .ldf
  • .log
  • .max
  • .mbx
  • .mdbasp
  • .mdf
  • .mef
  • .mkv
  • .mp4
  • .mpeg
  • .mrw
  • .msdb
  • .msg
  • .nbk
  • .ndf
  • .nef
  • .nrw
  • .odb
  • .odp
  • .ods
  • .odt
  • .odt
  • .orf
  • .p12
  • .p7b
  • .p7c
  • .pdb
  • .pdd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .pkg
  • .pl
  • .png
  • .ppt
  • .pptx
  • .psd
  • .psd
  • .psd
  • .pst
  • .pst
  • .ptx
  • .pub
  • .py
  • .r3d
  • .raf
  • .raw
  • .rb
  • .rtf
  • .rw2
  • .rwl
  • .sav
  • .sdf
  • .sh
  • .sln
  • .sql
  • .srf
  • .srw
  • .swf
  • .tar
  • .tar
  • .trc
  • .txt
  • .vb
  • .vcf
  • .vcxproj
  • .vmdk
  • .vob
  • .wb2
  • .wmv
  • .wpd
  • .xls
  • .xlsx
  • .xml
  • .zip

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • $recycle.bin
  • windows
  • Temp

It appends the following extension to the file name of the encrypted files:

  • .WSmile

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

  • %Desktop%\How to decrypt files.html

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.794.04
VSAPI OPR PATTERN File: 13.795.00

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

Scan your computer with your Trend Micro product to delete files detected as RANSOM_WANNASMILE.A. 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 the following Trend Micro Support pages for more information:

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Identify and terminate files detected as RANSOM_WANNASMILE.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 6

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Startup%\WannaSmile.lnk
  • %Application Data%\WannaSmile.exe
  • %Desktop%\How to decrypt files.html

Step 7

Delete this registry key

[ Learn More ]

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\Microsoft\Windows\CurrentVersion\Run
    • WannaSmile = %User Temp%\{Executed Malware Filename}.exe


Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_WANNASMILE.A. 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 9

Restore encrypted files from backup.


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