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JS_NEMUCOD.ELDSAUTC

October 11, 2017
 Analysis by: Rheniel Rhay Ramos
 ALIASES:

HEUR:Trojan.Script.Agent.gen (Kaspersky); JS.Downloader (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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.

It executes then deletes itself afterward.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

12,368 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

05 Oct 2017

Payload:

Connects to URLs/IPs

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.

Installation

This Trojan executes then deletes itself afterward.

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • https://{BLOCKED}allsandfloors.net/65b653109095b78e015379ebb15bdef7.flv
  • https://{BLOCKED}allsandfloors.net/65b653109095b78e015379ebb15bdef7.mp4

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan does the following:

  • The downloaded file will not be saved in the machine, thus, the file will be downloaded as a string and executed using the JavaScript command "eval".

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.710.03

FIRST VSAPI PATTERN DATE:

10 Oct 2017

VSAPI OPR PATTERN File:

13.711.00

VSAPI OPR PATTERN Date:

11 Oct 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

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