Analysis by: Donald Adrian Castillo
ALIASES:

Trojan-Downloader.JS.Agent.hfr (KASPERSKY)

 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: Dropped by other malware, 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.

  TECHNICAL DETAILS

File Size: 1,984 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 30 Jun 2015
Payload: 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.

Download Routine

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

  • http://{BLOCKED}64ty.com/images/onewindow1s.jpg
  • http://{BLOCKED}64ty.com/images/twowindow2s.jpg

It saves the files it downloads using the following names:

  • %User Temp%\3257860.exe - detected as TROJ_CRYPTWALL.DAC
  • %User Temp%\5174952.exe - detected as TROJ_CRYPTWALL.DMC

(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.)

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.762.02
FIRST VSAPI PATTERN DATE: 30 Jun 2015
VSAPI OPR PATTERN File: 11.763.00
VSAPI OPR PATTERN Date: 01 Jul 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

Remove malware/grayware files dropped/downloaded by JS_CRYPLOD.XXYG. (Note: Please skip this step if the threats listed below have already been removed.)

     
    • TROJ_CRYPTWALL.DAC
    • TROJ_CRYPTWALL.DMC

Step 4

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