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JS_NEMUCOD.R

December 23, 2016
 Analysis by: Pearl Charlaine Espejo
 ALIASES:

JS/TrojanDownloader.Nemucod.BTA (ESET-NOD32); TrojanDownloader:JS/Nemucod.QI (Microsoft); JS.Downloader.D (Symantec); JS:Trojan.JS.Downloader.HGB (BitDefender)

 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:

Spammed via email


This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

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

  TECHNICAL DETAILS

File Size:

25,723 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

08 Dec 2016

Payload:

Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Download Routine

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

  • http://{BLOCKED}ei.com/i1tko8uh
  • http://{BLOCKED}kerapts.com/mlkxh
  • http://{BLOCKED}med.ca/pyskwfnpu
  • http://{BLOCKED}baoan.com/ou0dwrv
  • http://{BLOCKED}d.com.ar/nd5u5kav1

It saves the files it downloads using the following names:

  • %User Temp%\tiA2ntuQY <- encrypted download file
  • %User Temp%\tiA2ntuQY.zk <- decrypted download file

(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 executes downloaded files :

  • %User Temp%\tiA2ntuQY.zk

(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.)

whose malicious routines are exhibited by the affected system.

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.960.03

FIRST VSAPI PATTERN DATE:

14 Dec 2016

VSAPI OPR PATTERN File:

12.961.00

VSAPI OPR PATTERN Date:

15 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

Identify and terminate files detected as JS_NEMUCOD.R

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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%/tiA2ntuQY
  • %User Temp%/tiA2ntuQY.zk

Step 5

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