Analysis by: David John Agni
 Modified by: Sammy Chua
ALIASES:

Troj/JSDldr-CX (Sophos); TrojanDownloader:JS/Nemucod.Y (Microsoft); JS/Downloader.Agent (AVG); Trojan-Downloader.JS.Agent.hlg (Kaspersky), JS/TrojDownloader.AGNT!tr (Fortinet);

 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: 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 does not have any propagation routine.

It does not have any backdoor routine.

It does not drop any other file.

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.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size: 3,015 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 29 Dec 2015
Payload: Connects to URLs/IPs, Downloads files

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.

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Dropping Routine

This Trojan does not drop any other file.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}trever.com/img/script.php?ibd1.jpg
  • http://{BLOCKED}trever.com/img/script.php?ibd2.jpg
  • http://{BLOCKED}trever.com/img/script.php?ibd3.jpg

It saves the files it downloads using the following names:

  • %User Temp%\1274905.exe
  • %User Temp%\4273205.exe
  • %User Temp%\2354869.exe

(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.

As of this writing, the said sites are inaccessible.

Information Theft

This Trojan does not have any information-stealing capability.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.240.08
FIRST VSAPI PATTERN DATE: 29 Dec 2015
VSAPI OPR PATTERN File: 12.241.00
VSAPI OPR PATTERN Date: 30 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

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 Temp%\1274905.exe
  • %User Temp%\4273205.exe
  • %User Temp%\2354869.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as JS_CRYPLOD.YYSJH. 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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