Downloader-ATO

Downloaders are designed to pull files from a remote website and execute the files that have been downloaded. As it is trivial for the malware author to modify the Downloader to refer to a different website or web address, McAfee write detection routines for Downloaders which as a general rule do not include these strings in the detection routines This allows McAfee to write more generic detections for these threats and to proactively protect customers against future minor variants.

Therefore it is not possible to guarantee which website and/or port is being communicated with.

Also, as the website being communicated is normally controlled by the malware author, any files being downloaded can be remotely modified and the behaviour of these new binaries altered - possibly with every user infection.

The Downloader-ATO trojan is likely to be installed on the victim's machine via an exploit when the victim browses a malicious web page. These exploits include - Exploit-ANIfile , Exploit-ByteVerify , Exploit-CodeBase  and Exploit-WMF .

Dynamic Malware Content

This trojan connects to designated servers which may download dynamic malware content to the victim's machine. These malware may include, but not limited to, BackDoor, KeyLogger and Exploit trojans. Servers known to be associated with this trojan are:

• toolbarbucks.biz
• toolbardollars.biz
• opt-in.biz
• serious-company.com

Supression of Alerts

The following system / firewall alert messages are monitored and suppressed by the trojan in order to evade visual detection by the user.

• Create rule for [application]

• Unexpected HTTP traffic to the above mentioned websites.
• Presence of one or more of the following file(s) downloaded and created by the Downloader-ATO trojan. The content of these files may vary:
  • %Windir%\tool[random number].exe
  • %Windir%\toolbar.exe
  • %Windir%\ms[random number].exe
  • %Windir%\kl[random number].exe
  • %Windir%\uniq
  • %Windir%\country.exe
  • %windir%\secure32.html
  • %Windir%\System32\paytime.com

N/A. Downloaders are not viruses, and as such do not themselves contain any method to replicate. However they may themselves be downloaded by other viruses and/or Trojans to be installed on the user's system.

Many of these additionally are mass spammed by the author to entice people into double-clicking on them.

Alternatively they may be installed by visiting a malicious web page (either by clicking on a link, or by the website hosting a scripted exploit which installs the Downloader onto the user's system with no user interaction.

All Users:

Please use the following instructions for all supported versions of Windows to remove threats and other potential risks:

1.Disable System Restore .

2.Update to current engine and DAT files for detection and removal.

3.Run a complete system scan.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

1. Please go to the Microsoft Recovery Console and restore a clean MBR.

On windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.