Analysis by: Jemimah Mae Molina
ALIASES:

Ransom:Win32/Eris.PA!MTB (Microsoft); RDN/Generic.dx (McAfee); Trojan-Ransom.Win32.Agent.avbn (Kaspersky); Troj/Ransom-FNK (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 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: 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.

  TECHNICAL DETAILS

File Size: 823,808 bytes
File Type: EXE
File Compression: PECompact
Memory Resident: No
Initial Samples Received Date: 08 Jul 2019
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.

Dropping Routine

This Ransomware drops the following files:

  • %ProgramData%\00000000.pky → contains public key
  • %ProgramData%\00000000.eky → contains encryption key

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Other Details

This Ransomware deletes itself after execution.

Ransomware Routine

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

  • .sys
  • .com
  • autoexec.bat
  • boot.ini
  • ntdetect.com
  • msdos.sys
  • io.sys
  • pagefile.sys
  • ntuser.dat
  • config.sys
  • ntldr

It avoids encrypting files found in the following folders:

  • windows
  • windows.old
  • system volume information
  • $recycle.bin
  • program files
  • program files (x86)
  • programdata

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

  • .ERIS

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

  • {Encrypted Directory}\@ READ ME TO RECOVER FILES @.txt

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.222.02
FIRST VSAPI PATTERN DATE: 08 Jul 2019
VSAPI OPR PATTERN File: 15.223.00
VSAPI OPR PATTERN Date: 09 Jul 2019

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • Troj.Win32.TRX.XXPE50FFF031

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

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 4

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.  
  • %ProgramData%\00000000.pky
  • %ProgramData%\00000000.eky
  • {Encrypted Directory}\@ READ ME TO RECOVER FILES @.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.ERIS.THGOHAIA. 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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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