Analysis by: Mio Fidel Villena
ALIASES:

Mal/Crypdum-A (SOPHOS_LITE); Gen:Heur.Ransom.HiddenTears.1 (BITDEFENDER)

 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: 38,400 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 09 Jan 2018
Payload: Displays message/message boxes, 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.

Installation

This Ransomware drops the following files:

  • %User Profile%\Documents\TEST\crypted -> mark that it finished its routine

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This Ransomware does the following:

  • It displays a pop-up window with the following message if %User Profile%\Documents\TEST folder is not existing:
  • This ransomware tries to encrypt files found in:
    • %User Profile%\Documents\TEST\

    However, due to errors in its code, it fails to perform its intended routine.
  • It is not capable of encrypting files.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.896.02
FIRST VSAPI PATTERN DATE: 10 Jan 2018
VSAPI OPR PATTERN File: 13.897.00
VSAPI OPR PATTERN Date: 11 Jan 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 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.
  • %User Profile%\Documents\TEST\crypted

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPWALKER.THAAOH. 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:


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