What are online virus scans?



Most often online virus scans are hosted on security companies' websites and use ActiveX technology (via Internet Explorer browser) to scan your computer, detecting any files that show up in the company's spyware or virus definitions. This is done by comparing the user's files against malware patterns in virus database.

Exact algorithms may vary from vendor to vendor, as does coverage. BitDefender claims it detects rootkits. Kaspersky Online Scanner boasts to have the highest detection rate among all antivirus products, and also updates its definitions hourly; others do it once a day. Some, such as Panda ActiveScan, require Internet Explorers, while others, such as Trend Micro Housecall, also support Firefox and Java platform (convenient for those with ActiveX disabled).

When should you use online virus scans?

Online scans are best used for sniffing out low-level threats that don't mess up with Internet connection. They usefully offer a reliable security testing solution while conveniently skipping the installation steps of stand-alone programs, and are usually compatible with security software already installed on your computer. If you're concerned about higher-level threats, you should consider strengthening your PC security with a combined software solution like firewall and antispyware (optionally with anti-spyware).

The disadvantages of online virus scans

Most scans are just malware detectors that cannot remove infected code unless you purchase the product. That's not necessarily a drawback if you're open to new removal software; the online scans test-drive the product's efficacy. (Housecall and BitDefender are pleasant exceptions, offering free removal services in addition to a free scan.)

You'll also still want to reserve a good chunk of time to the scans -- deep storage examination can take hours.

Popular scans

Some of the better-known online scans include:

Kaspersky (doesn't allow removal, however offers a choice of scan patterns ? like system memory, critical system areas, etc).

Trend Micro HouseCall (supports Firefox in addition to IE, have two scanning engines separate for ActiveX and Java technology, allows removal of infected files, detects spyware in addition to viruses).

BitDefender (free removal)

ESET Online Scan uses the same ThreatSense technology as their downloadable NOD32 antivirus.