Analysis by: Ryan Paolo Maglaque
ALIASES:

Trojan-Ransom.Win32.CryFile.zcd(Kaspersky);

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

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 deletes itself after execution.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 73,728 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 11 May 2017
Payload: Encrypts files, 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.

Other System Modifications

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

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 0

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Desktop%\wallpaper.jpg

(Note: The default value data of the said registry entry is {user preference}.)

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

Other Details

This Ransomware does the following:

  • Execute the following command:
    • vssadmin.exe Delete Shadows /All /Quiet

It deletes itself after execution.

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • .viki
  • .exe
  • .dll
  • .sys
  • .bat
  • .ini
  • .dat
  • .lnk

It avoids encrypting files found in the following folders:

  • windows
  • program files

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

  • .viki

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

  • {Driver Letter}\readme.txt
  • %Desktop%\readme.txt
  • %Desktop%\wallpaper.jpg

(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 leaves text files that serve as ransom notes containing the following text:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.400.01
FIRST VSAPI PATTERN DATE: 11 May 2017
VSAPI OPR PATTERN File: 13.401.00
VSAPI OPR PATTERN Date: 12 May 2017

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

Search and delete these files

[ 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.  
  • {Driver Letter}\readme.txt
  • %Desktop%\readme.txt
  • %Desktop%\wallpaper.jpg

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_VIKI.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 5

Reset your Desktop properties

[ Learn More ]

Step 6

Restore encrypted files from backup.


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