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JS_DLOADER.BN

August 31, 2017
 Analysis by: Byron Jon Gelera
 ALIASES:

JS/TrojanDownloader.Nemucod.DON (ESET-NOD32); TrojanDownloader:JS/Nemucod!rfn (Microsoft)

 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.

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

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

  TECHNICAL DETAILS

File Size:

19,526 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

23 Aug 2017

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.

Download Routine

This Trojan saves the files it downloads using the following names:

  • %User Profile%\AppData\Roaming169041.exe (Windows Vista and above)
  • %User Profile%\AppData\Roaming169042.exe (Windows Vista and above)
  • %Application Data%\Microsoft\Windows\Templates\{random number}.exe

(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.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ulahh.at/arsen.bin

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.630.02

FIRST VSAPI PATTERN DATE:

31 Aug 2017

VSAPI OPR PATTERN File:

13.631.00

VSAPI OPR PATTERN Date:

01 Sep 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

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 Profile%\AppData\Roaming169041.exe (Windows Vista and above)
  • %User Profile%\AppData\Roaming169042.exe (Windows Vista and above)
  • %Application Data%\Microsoft\Windows\Templates\{random number}.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as JS_DLOADER.BN. 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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