Analysis by: Marvelous Pelin
ALIASES:

Ransom:Win32/Teerac.A (Microsoft)

 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 connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 261,124 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 31 Jul 2017
Payload: Connects to URLs/IPs, Drops files, Encrypts files

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.

Installation

This Ransomware drops the following copies of itself into the affected system:

  • %Windows%\{random filename}.exe

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

It drops the following files:

  • %ProgramData%\{random filename}.png
  • %Application Data%\Microsoft\Windows\Themes\TranscodedWallpaper.jpg - set as desktop wallpaper

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %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.)

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Bit Torrent Application

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet\Explorer\Desktop\
General
WallPaperSource = %ProgramData%\{random filename}.png

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Application Data%\Microsoft\Windows\Themes\TranscodedWallpaper.jpg

It also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{random 7 characters} = %Windows%\{random filename}.exe

Other Details

This Ransomware connects to the following website to send and receive information:

  • https://{BLOCKED}omain.dp.ua/gate.php

Ransomware Routine

This Ransomware renames encrypted files using the following names:

  • {original filename and extension}.sifreli

NOTES:
It displays the following after encrypting:

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

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.566.08
FIRST VSAPI PATTERN DATE: 31 Jul 2017
VSAPI OPR PATTERN File: 13.567.00
VSAPI OPR PATTERN Date: 01 Aug 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

Restart in Safe Mode

[ Learn More ]

Step 4

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
    • Bit Torrent Application

Step 5

Delete this registry value

[ 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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • {random 7 characters} = %Windows%\{random filename}.exe

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.
  • %ProgramData%\{random filename}.png
  • %Application Data%\Microsoft\Windows\Themes\TranscodedWallpaper.jpg

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_SIFRELI.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 8

Restore encrypted files from backup.


Did this description help? Tell us how we did.