One of the techniques used by the malware to infect your computer is through USB keys. These malware place a malicious autorun.inf file in the USB key which runs automatically as soon as you insert the USB key into you PC. You can use free MCShield to protect your computer from such malware. MCShield is a USB oriented antimalware program. It is designed to prevent malware and virus infections emanating from portable USB drives. It automatically scans each removable USB drive that is inserted into your PC to thwart any possible malware attacks.
MCShield is available to be downloaded in form of a setup installer. The downloaded file can be used to install MCShield on your system. After the installation, it would attempt to update its database through the internet and open the MCShield Control Center window which can be used to change its settings.
In the MCShield Control Center, you can choose various settings like to run MCShield automatically with Windows logon. In the Scanner section, you can select what kind of disk drives you want it to scan, perform in-depth signature scan, enable heuristics etc. There are preset settings like Fastest and Bulletproof which can change the settings for faster and extreme performance. If you select the Interactive mode then it displays more information about the items being scanned.
When you insert a USB key or other kind of removable disk drive, MCShield automatically scans it for any potential infections. If it finds malicious or suspicious files, it delete or renames them. You are shown the log of what actions were taken in a log file after 5 seconds. However, if you select the interactive mode in the Scanner section of MCShield Control Center, then it would display more information like MD5 values, option to scan the file over at VirusTotal etc., before asking your permission to process the suspicious files.
MCShield has an option to whitelist the files that you think are legitimate and cannot harm your system. To do this you have to open the Control Center (by double-clicking on the notification area icon). Then select the Whitelist section. Right-click and select Add Item and then select a file that you do not want to be scanned. This is a great option to prevent MCShield from renaming harmless files.
MCShield detects the malicious files using its heuristic engine. But it also has a small database of malware signatures which can be used to detect some of the known malware present on your USB drives. It has an in-built updater which attempts to update the signature database after every two hours. Additionally, there is an offline database updater program that you can download from the MCShield website.
MCShield protects USB drives from malware not only by renaming suspicious looking autorun.inf files, but also by detecting known malicious files. Although MCShield can prevent infections transmitted through removable drives, it is not a complete anti-malware solution. You should not depend entirely on MCShield for protecting your PC. In addition to MCShield, you must install a full antivirus like avast! in order to fully protect your PC.
You can download MCShield from http://www.mcshield.net/.