Analysis by: John Donnie Celestre
ALIASES:

JS/Psyme (AVG), JS/TrojanDownloader.Agent.RXY trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 16,666 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 14 May 2018

Arrival Details

This Trojan 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 Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Classes\
mscfile

HKEY_CURRENT_USER\Software\Classes\
mscfile\shell

HKEY_CURRENT_USER\Software\Classes\
mscfile\shell\open

HKEY_CURRENT_USER\Software\Classes\
mscfile\shell\open\
command

It also creates the following registry entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\Classes\
mscfile\shell\open\
command
(Default) = "%System%\wscript.exe" "%User Temp%\{file_name}}.js" {parameter}

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}jwfoby39v7o7b.{BLOCKED}/update.php
  • http://www.{BLOCKED}lligsteforbruksln-ixb.{BLOCKED}/update.php

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.250.06
FIRST VSAPI PATTERN DATE: 14 May 2018
VSAPI OPR PATTERN File: 14.251.00
VSAPI OPR PATTERN Date: 15 May 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

Delete this registry key

[ 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\Classes
    • mscfile

Step 4

Scan your computer with your Trend Micro product to delete files detected as JS_NEMUCOD.THEADAH. 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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