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TROJ_DLOADR.AOI

July 09, 2013
 Analysis by: Roland Marco Dela Paz
 ALIASES:

Downloader (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet


This Trojan accesses certain websites to report infection and to get instructions on its download routines.

As per current analysis, the malware attempts to download certain files.

This Trojan may be downloaded by other malware/grayware from remote sites.

  TECHNICAL DETAILS

File Size:

49,664 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Apr 2012

Payload:

Downloads files

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • TROJ_ARTIEF.AOI

It may be downloaded from the following remote sites:

  • http://www.{BLOCKED}lue.net/sv//cache/yltyWwH.exe

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System Root%\Documents and Settings\All Users\Local Settings\Temp\msdubmna.com

It adds the following processes:

  • wuauclt.exe

It injects itself into the following processes as part of its memory residency routine:

  • wuauclt.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
55011 = %System Root%\Documents and Settings\All Users\Local Settings\Temp\msdubmna.com

NOTES:

This Trojan accesses the following websites to report infection and to get instructions on its download routines:

  • http://{BLOCKED}sadhasiodo.com/blog/image.php
  • http://{BLOCKED}lililili.com/blog/image.php
  • http://{BLOCKED}jadsdaskld.net/blog/image.php

As per current analysis, the malware attempts to download the following files:

  • http://{BLOCKED}ing.net/images/flash.dll - corrupted archive
  • http://{BLOCKED}ing.net/images/xaxa.txt - corrupted archive
  • http://{BLOCKED}ing.net/images/java_blog.exe - detected as TSPY_ZBOT.CJKA

It then executes the downloaded file. As a result, malicious routines of the downloaded file are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.933.01

FIRST VSAPI PATTERN DATE:

23 Apr 2012

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

Remove malware/grayware files that dropped/downloaded TROJ_DLOADR.AOI

      TROJ_ARTIEF.AOI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • 55011 = %System Root%\Documents and Settings\All Users\Local Settings\Temp\msdubmna.com

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DLOADR.AOI. 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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