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RANSOM_HIDDENTEARHOBOT.A

September 04, 2017
 ALIASES:

Ransom.HiddenTear (NORTON); Trojan:Win32/Dynamer!rfn (Microsoft)

 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:

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 drops files as ransom note.

  TECHNICAL DETAILS

File Size:

119,808 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

22 Aug 2017

Payload:

Displays message/message boxes, 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.

Ransomware Routine

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

  • HOW_TO_RECOVER_ENCRYPTEDFILES
  • .hobot2good

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

  • .hobot2good

It drops the following file(s) as ransom note:

  • {folder of encrypted files}\HOW_TO_RECOVER_ENCRYPTEDFILES.txt

NOTES:

This ransomware shows the following window after execution:

The hide button hides the window. The exit and delete buttons runs the following process to delete itself:

cmd.exe /C choice /C Y /N /D Y /T 3 & Del {malwarepath}

It the terminates.

The send key button generates new ID and password for encryption.

There are four text boxes listing folders to be encrypted. Default values of entries include:

  • {all drive letters except C:\}
  • C:\Users
  • C:\ProgramData
  • C:\ProgramFiles
  • C:\ProgramFiles (x86)

The start button triggers encryption routine. Entries can be edited before triggering the start button. It triggers the exit and delete routine after encrypting all folders listed in all four text boxes.

It drops ransom note {folder of encrypted files}\HOW_TO_RECOVER_ENCRYPTEDFILES.txt that contains the following:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.612.04

FIRST VSAPI PATTERN DATE:

23 Aug 2017

VSAPI OPR PATTERN File:

13.613.00

VSAPI OPR PATTERN Date:

24 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

Identify and terminate files detected as RANSOM_HIDDENTEARHOBOT.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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.  
  • {folder of encrypted files}\HOW_TO_RECOVER_ENCRYPTEDFILES.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_HIDDENTEARHOBOT.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 6

Restore encrypted files from backup.


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