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RANSOM.WIN32.OUTSIDER.THABAOAH

January 23, 2019
 Analysis by: Michael Jhon Ofiaza
 ALIASES:

Trojan-Ransom.Win32.Cryptor.cdk (Kaspersky)

 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, Dropped by other malware


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:

12,288 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

07 Dec 2018

Payload:

Drops files, Terminates processes, 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.

Process Termination

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

  • null.exe
  • nan.exe

Other Details

This Ransomware does the following:

  • Terminates if the default language ID is any of the following:
    • 419 - RUSSIAN
    • 43F - KAZAK
    • 423 - BELARUSIAN
    • 422 - UKRANIAN
    • 444 - TATAR
    Terminates if the Keyboard layout is any of the following:
    • 419 - RUSSIAN
    • 43F - KAZAK
    • 423 - BELARUSIAN
    • 422 - UKRANIAN
  • Delete shadow copy

Ransomware Routine

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

  • .protected
  • HOW_TO_RESTORE_FILES.txt
  • Windows
  • Program Files
  • Program Files (x86)
  • $Recycle.bin
  • System Volume information

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

  • .protected

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

  • {Encrypted Folder}\HOW_TO_RESTORE_FILES.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.680.03

FIRST VSAPI PATTERN DATE:

10 Dec 2018

VSAPI OPR PATTERN File:

14.681.00

VSAPI OPR PATTERN Date:

11 Dec 2018

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 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.
  • {Encrypted Folder}\HOW_TO_RESTORE_FILES.txt

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM.WIN32.OUTSIDER.THABAOAH. 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 5

Restore encrypted files from backup.


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