RANSOM_TRESORAS.A

April 25, 2017
 Analysis by: John Anthony Banes
 ALIASES:

Trojan-Ransom.Win32.Cryptor.hp (Kaspersky); Python/Filecoder.S trojan (NOD32)

 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:

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:

4,476,159 bytes

File Type:

, EXE

Memory Resident:

No

Initial Samples Received Date:

05 Apr 2017

Payload:

Drops 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.

Autostart Technique

This Ransomware drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • {malware filename}.exe

Dropping Routine

This Ransomware drops the following files:

  • {malware path}\NOTE.html - ransom note

Other Details

This Ransomware does the following:

  • It deletes shadow copies:
    vssadmin.exe delete shadows /all /quiet
  • It disables Windows automatic repair and error recovery:
    bcdedit.exe /set {default} recoveryenabled no
    bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures

NOTES:

NOTE.html contains the following message:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.336.02

FIRST VSAPI PATTERN DATE:

12 Apr 2017

VSAPI OPR PATTERN File:

13.337.00

VSAPI OPR PATTERN Date:

13 Apr 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

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.  
  • {malware path}\NOTE.html

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_TRESORAS.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 5

Restore encrypted files from backup.


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