Analysis by: Janus Agcaoili
ALIASES:

JS.Downloader (Symantec), TrojanDownloader:JS/Swabfex (Microsoft), Trojan-Downloader.JS.Cryptoload.ba (Kaspersky)

 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 as an attachment to email messages spammed by other malware/grayware or malicious users. It 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: 7,625 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 11 Dec 2015

Arrival Details

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

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ebextraub,cin/87.exe?1
  • http://{BLOCKED}.{BLOCKED}.52.231/87.exe?1

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.204.06
FIRST VSAPI PATTERN DATE: 11 Dec 2015
VSAPI OPR PATTERN File: 12.205.00
VSAPI OPR PATTERN Date: 12 Dec 2015

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

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