Analysis by: Francis Xavier Antazo

 ALIASES:

Ransom:MSIL/Ryzerlo.A (Microsoft); a variant of MSIL/Filecoder.Y (ESET);

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Propagates via removable drives, Propagates via network shares

This ransomware uses Pokemon Go probably to hide its true nature. It tries to spread copies of itself on removable drives as PokemonGo.exe. It also tries to drop copies of itself on shared folders and mapped network drives as PokemonGo.exe.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives via removable drives. It 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 an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 638,464 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 Aug 2016
Payload: Connects to URLs/IPs, Encrypts files, , Terminates processes

Arrival Details

This Trojan arrives via removable drives.

It may arrive via network shares.

It 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 the following files:

  • C:\Users\{username}\Desktop\هام جدا.txt -> ransom note
  • C:\Users\{username}\Desktop\pk -> key
  • %User Startup%\{random characters}.exe -> (to be detected as Ransom_POGOTEAR.A)

(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.)

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

  • (: لقد تم تشفير ملفاتكم، لفك الشفرة فلكسي موبيليس للعنوان التالي me.{BLOCKED}20152015@mt2015.com وشكرا على كرمكم مسبقا

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
PokemonGo = "{Malware file path and file name}"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
SpecialAccounts\UserList
Hack3r = "0"

Propagation

This Trojan drops copies of itself in the following drives:

  • {Destination Root*}\PokemonGo.exe
    • All fixed drives, removable drives, shared folders and mapped network drives

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
OPEN=PokemonGo.exe
ICON=PokemonGo.exe

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • SMΔRTP

Other Details

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

  • http://{BLOCKED}.{BLOCKED}.0.169/PokemonGo/write.php?info={computername}-{username} {key}<br>

It encrypts files with the following extensions:

  • .txt
  • .rtf
  • .doc
  • .pdf
  • .mht
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .odt
  • .jpg
  • .png
  • .csv
  • .sql
  • .mdb
  • .sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml
  • .psd
  • .htm
  • .gif
  • .png

It renames encrypted files using the following names:

  • {original file name and file extension}.locked

NOTES:

This ransomware only drops the AUTORUN.INF file on removable drives.

It creates administrator level user with the following credentials:

  • username: Hack3r
  • password: Hack3r

It locks the screen with the following image:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.716.04
FIRST VSAPI PATTERN DATE: 15 Aug 2016
VSAPI OPR PATTERN File: 12.717.00
VSAPI OPR PATTERN Date: 16 Aug 2016

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_POGOTEAR.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 4

Restart in Safe Mode

[ Learn More ]

Step 5

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.  
  • C:\Users\{username}\Desktop\هام جدا.txt
  • C:\Users\{username}\Desktop\pk

Step 6

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
    • PokemonGo = "{Malware file path and file name}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList
    • Hack3r = "0"

Step 7

Search and delete AUTORUN.INF files created by RANSOM_POGOTEAR.A that contain these strings

[ Learn More ]
  • [AutoRun]
  • OPEN=PokemonGo.exe
  • ICON=PokemonGo.exe

Step 8

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