Analysis by: Michael Jay Villanueva

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This Trojan may be dropped by other malware.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 61,440 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 07 May 2017
Payload: Connects to URLs/IPs, Compromises system security

Arrival Details

This Trojan may be dropped by the following malware:

Installation

This Trojan drops the following file(s)/component(s):

  • {Current Malware Path, Name, and Extension}.mui <- contains the Tor URL

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{GUID generated using the affected system's computer name}

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Local Security Authority = "%Windows%\lsasvs.exe"

Other Details

This Trojan connects to the following website to send and receive information:

  • {BLOCKED}nxf743znk7.onion
  • {BLOCKED}igdz4q7f6q.onion
  • {BLOCKED}ms2ivmt5og.onion

It requires the following additional components to properly run:

  • {Current Malware Path}\TaskHost\Tor\taskhosts.exe <- Tor client to access Tor URL
  • {Current Malware Path}\lsass.bin <- contains the TOR client package and its components

It does the following:

  • Execute arbitrary shell codes
  • Change the time delay for every connection
  • Download and Execute arbitrary files
    • May receive download URLs with the following protocol: FTP, HTTP, HTTPS
    • if the download has ".jpg" extension, it saves it as ".exe" and execute
    • if the download as ".png" extension, it saves it as ".dll" and loads as a library
  • Installs the Tor client from the bin component
  • Sleeps for 24hrs after every connection
  • Grants standard access rights to the group "EVERYONE"
  • Executes the following files:
    • {Current Malware Path}\Taskhcst.exe -> also dropped by WORM_WCRY.H, detected as Ransom_WCRY.H

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.410.05
FIRST VSAPI PATTERN DATE: 16 May 2017
VSAPI OPR PATTERN File: 13.411.00
VSAPI OPR PATTERN Date: 17 May 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

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Local Security Authority = "%Windows%\lsasvs.exe"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • {Current Malware Path}\TaskHost

Step 6

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.
  • {Current Malware Path, Name, and Extension}.mui
  • {Current Malware Path}\lsass.bin
  • {Current Malware Path}\taskhcst.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_WCRY.H. 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.


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