Threat behavior
TrojanDownloader:Win32/Zayaho.A is a trojan that downloads and runs other files without the express consent of the affected user. If TrojanDownloader:Win32/Zayaho.A is in the %temp% folder when it runs, it takes the following actions:
- Downloads a specific file from a certain Web site, saving the file to the %temp% folder with a random eight-character name and a .exe extension.
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Runs the downloaded file.
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Prevents one or more applications on the host computer from blocking its behavior. For example, the trojan can send window messages to Anvir Task Manager to allow the Trojan to access the network without user consent.
If TrojanDownloader:Win32/Zayaho.A is not in the %temp% folder when it runs, it creates a copy of itself named svchst.exe in the %temp% folder, runs that copy (svchst.exe), and exits. The svchst.exe program then deletes the original trojan downloader file.
Prevention
Take the following steps to help prevent infection on your system:
Enable a firewall on your computer.
Get the latest computer updates.
Use up-to-date antivirus software.
Use caution with attachments and file transfers.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
Click Start, and click Control Panel.
Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
Click Change Windows Firewall Settings.
Select On.
Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows XP
Click Start, and click Control Panel.
Click System.
Click Automatic Updates.
Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software that is updated with the latest signature files. Antivirus software is available from several sources. For more information, see http://www.microsoft.com/athome/security/downloads/default.mspx
Use caution with attachments and file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.
