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RANSOM_RAPID.THCBFAH

April 11, 2018
 Analysis by: Michael Jhon Ofiaza
 ALIASES:

Ransom:Win32/Raid.A (Microsoft) , Trojan-Ransom.Win32.Gen.hpw (Kaspersky) , Ransom-O (Nai)

 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.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

112,640 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Mar 2018

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.

Other System Modifications

This Ransomware adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\AppDataLow\
Software
key0 = BgIAAACkAABSU0ExAAQAAAEAAQDNumU5ggpZQLtLjfE0kmeHrzMwGia7edfDoiXAg0s3VEzMrSpnllYcQhNOedPhQYLMjEimQmeIvX9jr9XqKpu1d7a2AmF4amahAfConzEBuywCeD+aALwWmWZIcfdA+OqEaSCZXMmopYYtFg3LHxYz/O6U0l/3dmXPXtGkuK6wqg==

HKEY_CURRENT_USER\Software\AppDataLow\
Software
key2 = {random 8 characters}

HKEY_CURRENT_USER\Software\AppDataLow\
Software
key1 = {random hex characters}

Other Details

This Ransomware does the following:

  • Avoids encrypting computers with Russian locale
  • Avoids encrypting files with the following extensions:
    • exe
    • dll
    • sys

Ransomware Routine

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

  • Windows
  • $Recycle.Bin
  • Boot
  • Microsoft
  • MS0Cache
  • Program Files
  • Program Files (x86)
  • ProgramData
  • Recovery
  • System Volume Information

It renames encrypted files using the following names:

  • {random numbers}.{random 5 characters}

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

  • {encrypted folder}\DECRYPT.{Random 5 Characters}.txt

NOTES:

This ransomware displays the following:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.152.01

FIRST VSAPI PATTERN DATE:

25 Mar 2018

VSAPI OPR PATTERN File:

14.153.00

VSAPI OPR PATTERN Date:

26 Mar 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

Restart in Safe Mode

[ Learn More ]

Step 4

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\AppDataLow\Software
    • key0 = BgIAAACkAABSU0ExAAQAAAEAAQDNumU5ggpZQLtLjfE0kmeHrzMwGia7edfDoiXAg0s3VEzMrSpnllYcQhNOedPhQYLMjEimQmeIvX9jr9XqKpu1d7a2AmF4amahAfConzEBuywCeD+aALwWmWZIcfdA+OqEaSCZXMmopYYtFg3LHxYz/O6U0l/3dmXPXtGkuK6wqg==
  • In HKEY_CURRENT_USER\Software\AppDataLow\Software
    • key2 = {random 8 characters}
  • In HKEY_CURRENT_USER\Software\AppDataLow\Software
    • key1 = {random hex characters}

Step 5

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}\DECRYPT.{Random 5 Characters}.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_RAPID.THCBFAH. 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 7

Restore encrypted files from backup.


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