Analysis by: Nikko Tamana
ALIASES:

JS/Agent.GUD!tr.dldr (Fortinet), Trojan-Downloader.JS.Agent (Ikarus), Trojan-Downloader.JS.Agent.gud (Kaspersky), TrojanDownloader:JS/Qakbot.K (Microsoft)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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.

  TECHNICAL DETAILS

File Size: 6,382 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 17 Sep 2013

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 downloads the file from the following URL and renames the file when stored in the affected system:

  • http://{BLOCKED}uytdk.info/4
  • http://698353.{BLOCKED}gcrew.net/4
  • http://dns7.parkpage.{BLOCKED}tionapi.com/4
  • http://{BLOCKED}iakfuuasd.net/4
  • http://{BLOCKED}n.org/4
  • http://{BLOCKED}nz.net/4
  • http://{BLOCKED}ausj.org/4
  • http://{BLOCKED}carusled.org/4

It saves the files it downloads using the following names:

  • %User Temp%\{random file name 1}.exe
  • %User Temp%\{random file name 2}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.284.03
FIRST VSAPI PATTERN DATE: 17 Sep 2013
VSAPI OPR PATTERN File: 10.285.00
VSAPI OPR PATTERN Date: 18 Sep 2013

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

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%\{random file name 1}.exe
  • %User Temp%\{random file name 2}.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_KRYPTIK.ER. 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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