Analysis by: RonJay Kristoffer Caragay
ALIASES:

JS/TrojanDownloader.Nemucod.BVS trojan (ESET-NOD32); Trojan-Ransom.Script.Locky (Ikarus); JS.Downloader (Symantec), Troj/JSDldr-VQ (Sophos)

 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: Downloaded from the Internet, Via email

This Trojan arrives as attachment to mass-mailed email messages. It 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 the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 615 bytes
File Type: Script
Memory Resident: No
Initial Samples Received Date: 20 Dec 2016
Payload: Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan arrives as attachment to mass-mailed email messages.

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

Download Routine

This Trojan accesses the following websites to download files:

  • http://www.{BLOCKED}ni.com/counter/?a={value}&m=binging&i={value}
  • http://www.{BLOCKED}oscaclub.it/counter/?a={value}&m=binging&i={value}&m=binging&i={value}
  • http://www.{BLOCKED}form.net/counter/?a={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}
  • http://{BLOCKED}81.fr/counter/?a={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}
  • http://{BLOCKED}ch.com/counter/?a={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}&m=binging&i={value}

It saves the files it downloads using the following names:

  • %User Temp%\a2.exe ← detected as TROJ_KOVTER.DZD
  • %User Temp%\a1.exe ← detected as Ransom_LOCKY.DZD
  • %User Temp%\a.txt

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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

NOTES:

The URL it accesses contains script that downloads and executes a file from the following URLs:

  • http://www.{BLOCKED}ntsa.ro/counter/?i={value}a={value}&r={value}
  • http://{BLOCKED}oatlantico.com.br/counter/?i={value}a={value}&r={value}
  • http://{BLOCKED}ciondeairesplit.com/counter/?i={value}a={value}&r={value}
  • http://{BLOCKED}apage.com/counter/?i={value}a={value}&r={value}
  • http://{BLOCKED}is-avocat.com/counter/?i={value}a={value}&r={value}

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 13.106.08
FIRST VSAPI PATTERN DATE: 20 Dec 2016
VSAPI OPR PATTERN File: 13.107.00
VSAPI OPR PATTERN Date: 20 Dec 2016

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

Remove the malware/grayware file dropped/downloaded by JS_LOCKY.DLDSDZD. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • Ransom_LOCKY.DZD
    • TROJ_KOVTER.DZD

Step 4

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.  
  • %User Temp%\a.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as JS_LOCKY.DLDSDZD. 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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