Scanning the computer from an online location provides several advantages over the classic local scan. The most prominent one is that the risk of a virus infection of the virus scanner is not present and that the engine used by the scanner is usually up to date. A local virus scanner needs to be updated regularly to stay effective.
An Internet connection is needed on the other hand to perform the scan which sometimes can be a problem if the system is not booting into the operating system. A Live CD may help but many Online Virus Scanners demand the Internet Explorer which is obviously unavailable on Linux systems.
Online Virus Scanners can be used to get a "second opinion" without having to install another anti-virus software on the computer. It is probably a good idea to use as many of the virus scanners as possible if it is suspected that the system was infected by a virus. Below is a list of services that provide access to online virus scanners.
Bitdefender Online Scanner - requires Internet Explorer 4+. Update: Now also compatible with other browsers including Google Chrome.
BullGuard Virus Scan - Seems to require browser extensions or downloads, even though the site claims it does not.
Comodo Free Online Scanner - Requires the installation of plug-ins or Active-X controls. Is not compatible with Google Chrome, has not been updated in a while it appears.
Eset Online Scanner - requires Internet Explorer. Update: Chrome, Firefox and other browser users need to download a small file to run it.
F-Secure Online Scanner - works only with Internet Explorer 6+. Update: Downloads a file to the system that you need to execute.
Kaspersky Free Virus Scan - browser independent, downloads roughly 25 Megabytes of files prior to scanning. User can select locations to scan. The scanner does not remove infected files.
McAfee FreeScan - requires Microsoft Internet Explorer 5+
Microsoft OneCare Live - requires Internet Explorer. Update: no longer available.
Microsoft Safety Scanner - Downloads a file to your system that you need to run to test your PC for malware.
Norton Security Scan - Downloads a file to the local system that you need to execute to scan your system for malicious programs and processes.
Panda ActiveScan - requires Internet Explorer or Firefox, does not run in Opera. Update: Downloads a small file to the system that you need to run.
Shields Up! - browser independent but very slow and unresponsive currently.
Symantec Security Check - down or gone.
Trendsecure HouseCall - Java based scanner, works with Java compatible browsers.
Windows Security - Trojan scan that requires Internet Explorer 5+
Avast Online Scanner - file size limit of 16 Megabyte
Metascan online - Supports files up to 80 Megabytes in size, scans with 40 different engines.
NoVirusThanks - 20 Megabyte file size limit, can also scan websites. [no longer available]
VirScan - Free service that accepts files up to 20 Megabyte in size and scans them against multiple antivirus engines.
Virus Scan - file size limit of 10 Megabyte. Update: limit increased to 25 Megabyte.
Virus Total - email upload option, 64 Megabyte file size limit, can scan web pages.
Do you know any other services where users can scan files or the computer ?
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Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.