Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 90,112 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 24 Feb 2017
Payload: Drops files, Encrypts files, Displays message/message boxes

Arrival Details

This Trojan 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 Trojan drops a copy of itself in the following folders using different file names:

  • {all removable and fixed drives}\{random values}.exe - set attributes to Hidden

It drops the following files:

  • %Desktop%\{unique id}.HTML - ransom note
  • %Application Data%\{unique id}.HTML - ransom note
  • %Application Data%\{unique id}
  • {Fixed and Removable Drive Letter}:\{Shortcut files with the filename of every folder in the removable and fixed drive}
    • The malware creates these shortcut files in order to trick the user due to its folder icon and legit filenames.
    • The target path of these shortcuts is set to: %System%\cmd.exe /C explorer.exe "{folder name - where original files are stored}" & type "{random values}.exe - dropped copy of the malware" - "%tmp%\{random values}.exe - dropped copy of the malware" & start "{folder name - where original files are stored}" "%tmp%\{random values}.exe - dropped copy of the malware"
  • %Application Data%\{10 digit number}

(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.. %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 Details

This Trojan encrypts files with the following extensions:

  • .accdb
  • .backup
  • .backupdb
  • .bak1
  • .bak2
  • .bak3
  • .bak4
  • .bpdx
  • .docm
  • .docx
  • .docxml
  • .email
  • .jpeg
  • .potm
  • .potx
  • .ppsm
  • .ppsx
  • .pptm
  • .pptx
  • .sql1
  • .sql2
  • .sqlite
  • .tiff
  • .vbox
  • .vhdx
  • .vmdk
  • .vmsd
  • .vmxf
  • .wbcat
  • .xlam
  • .xlsb
  • .xlsm
  • .xlsx
  • .xltm
  • .xltx

It does the following:

  • This ransomware deletes all shadow copies by executing the following command:
    • vssadmin delete shadows/all/quiet
  • It prevents encrypting files containing any of the strings in its full path name:
    • games
    • program files (x86)
    • program files
    • windows

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 13.240.04
FIRST VSAPI PATTERN DATE: 24 Feb 2017
VSAPI OPR PATTERN File: 13.241.00
VSAPI OPR PATTERN Date: 25 Feb 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

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.
%Desktop%\{unique id}.HTML
%Application Data%\{unique id}.HTML
%Application Data%\{unique id}
{Fixed and Removable Drive Letter}:\{Shortcut files with the filename of every folder in the removable and fixed drive}

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom_SPORA.AUSCC. 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 6

Restore encrypted files from backup.


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