Alert level

Win32/Renos


Encyclopedia entry
Updated: Mar 11, 2009  |  Published: Apr 16, 2007

Aliases
  • Win32.Renos (F-secure)

Alert Level (?)
High

Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.


Summary

The Win32/Renos family automatically downloads potentially unwanted software such as SpySheriff, SpyAxe, SpyFalcon, SpyDawn, SpywareStrike, and other similarly named programs. These programs typically present erroneous warnings claiming the system is infected with spyware and offer to remove the alleged spyware for a fee. In some cases, the programs may also cause system instability.


Symptoms

Symptoms of a Win32/Renos infection may differ according to the particular variant. The trojan may display a red (possibly blinking) icon in the system tray, such as the one in the following image:
Win32/Renos may also display a deceptive message which warns that the computer is infected; the warning encourages the user to download certain software that allegedly provides malware or spyware protection. Following are two variations of a warning message that may appear:
 


Technical Information (Analysis)

The Win32/Renos family automatically downloads potentially unwanted software such as SpySheriff, SpyAxe, SpyFalcon, SpyDawn, SpywareStrike, and other similarly named programs. These programs typically present erroneous warnings claiming the system is infected with spyware and offer to remove the alleged spyware for a fee. In some cases, the programs may also cause system instability.


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
  1. Click Start, and click Control Panel.
  2. Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
  3. Click Change Windows Firewall Settings.
  4. Select On.
  5. Click OK.
To turn on the Windows Firewall in Windows Vista
  1. Click Start, and click Control Panel.
  2. Click Security.
  3. Click Turn Windows Firewall on or off.
  4. Select On.
  5. 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
  1. Click Start, and click Control Panel
  2. Click System.
  3. Click Automatic Updates.
  4. 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/protect/computer/viruses/vista.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.


Recovery

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft online scanner (http://safety.live.com). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.