Analysis by: Oliver Ramirez

ALIASES:

Trojan.Win32.Pakes.ausu (KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

  TECHNICAL DETAILS

File Size: 165,377 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 May 2017
Payload: 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:

  • %AppDataLocal%\Microsoft Help\{8 random characters}.exe

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{8 random characters} = %Application Data%\Microsoft\{8 random characters}.exe

It drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • {8 characters random}.lnk

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\{8 random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\{8 random characters}

Other Details

This Ransomware does the following:

  • Executes following commands: -vssadmin.exe delete shadows /all /quiet

Ransomware Routine

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

  • .bat
  • .com
  • .cpl
  • .dll
  • .exe
  • .ini
  • .lnk
  • .msc
  • .msp
  • .scf
  • .scr
  • .sys

It avoids encrypting files found in the following folders:

  • %Windows%

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

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

  • !______PATAGONIA5000@{BLOCKED}MAIL.COM______.rar

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.428.04
FIRST VSAPI PATTERN DATE: 25 May 2017
VSAPI OPR PATTERN File: 13.429.00
VSAPI OPR PATTERN Date: 26 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

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 = {8 random characters}
  • In HKEY_LOCAL_MACHINE
    • SOFTWARE = {8 random characters}

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {8 random characters} = "%Application Data%\Microsoft\{8 random characters}.exe

Step 6

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.
  • %User Startup%\{8 random characters}.lnk

Step 7

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


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