BleepingComputer.com: Quick question I think!

If I had a virus in quarantine could it still be active? I have been fighting with a "virus" for weeks causing internet connectivity issues. I recently updated MBAM one more time and figured I would run it. When I opened it I randomly clicked to the quarantine tab and saw a virus in there (trojan I wish I had taken down the name) and decided to actually delete it. Since then I seem to be running okay...weird? Let me know some thoughts on that...Thanks

When an anti-virus or security program quarantines a file and moves it into a virus vault (chest) or a dedicated Quarantine folder, that file is safely held there and no longer a threat. The file is essentially disabled and prevented from causing any harm to your system through proprietary security routines which may copy, rename, encrypt and password protect the file as part of the moving process. Quarantine is just an added safety measure which allows you to view and investigate the files while keeping them from harming your computer.

One reason for doing this is to prevent deletion of a legitimate file file that may have been flagged as a "false positive" especially if the scanner uses heuristic analysis technology. Heuristics is the ability of a scanning program to detect possible new variants of malware before the vendor can get samples and update the program's definitions for detection. Heuristics uses non-specific detection methods to find new or unknown malware which allows the anti-virus to detect and stop if before doing any harm to your system. The disadvantage to using heuristics is that it is not as reliable as signature-based detection (blacklisting) and can potentially increase the chances that a non-malicious program is flagged as suspicious or infected. If that is the case, then you can restore the file and add it to the exclusion or ignore list. When the quarantined file is known to be malicious, you can delete it at any time by launching the program which removed it, going to the Quarantine tab, and choosing the option to delete.

Keep in mind, however, that if these files are left in quarantine, other scanning programs and security tools may flag them as a threat while in the quarantined area so don't be alarmed if you see such an alert. Just delete the quarantined items after confirming they are malware and subsequent scans should no longer detect them.

• Clean, Quarantine, or Delete?

Well apparently it didn't actually solve my problem, just conveniently booted fine first time after i uninstalled that quarantined file, but thank you for the sexplanation it helped me understand the purpose of that more.