screenshot of open source clamwin antivirus software running in wine on ubuntu linux
many users install antivirus software can detect , eliminate known viruses when computer attempts download or run executable file (which may distributed email attachment, or on usb flash drives, example). antivirus software blocks known malicious websites attempt install malware. antivirus software not change underlying capability of hosts transmit viruses. users must update software regularly patch security vulnerabilities ( holes ). antivirus software needs regularly updated in order recognize latest threats. because malicious hackers , other individuals creating new viruses. german av-test institute publishes evaluations of antivirus software windows , android.
examples of microsoft windows anti virus , anti-malware software include optional microsoft security essentials (for windows xp, vista , windows 7) real-time protection, windows malicious software removal tool (now included windows (security) updates on patch tuesday , second tuesday of each month), , windows defender (an optional download in case of windows xp). additionally, several capable antivirus software programs available free download internet (usually restricted non-commercial use). such free programs commercial competitors. common security vulnerabilities assigned cve ids , listed in national vulnerability database. secunia psi example of software, free personal use, check pc vulnerable out-of-date software, , attempt update it. ransomware , phishing scam alerts appear press releases on internet crime complaint center noticeboard. ransomware virus posts message on user s screen saying screen or system remain locked or unusable until ransom payment made. phishing deception in malicious individual pretends friend, computer security expert, or other benevolent individual, goal of convincing targeted individual reveal passwords or other personal information.
other commonly used preventative measures include timely operating system updates, software updates, careful internet browsing (avoiding shady websites), , installation of trusted software. browsers flag sites have been reported google , have been confirmed hosting malware google.
there 2 common methods antivirus software application uses detect viruses, described in antivirus software article. first, , far common method of virus detection using list of virus signature definitions. works examining content of computer s memory (its random access memory (ram), , boot sectors) , files stored on fixed or removable drives (hard drives, floppy drives, or usb flash drives), , comparing files against database of known virus signatures . virus signatures strings of code used identify individual viruses; each virus, antivirus designer tries choose unique signature string not found in legitimate program. different antivirus programs use different signatures identify viruses. disadvantage of detection method users protected viruses detected signatures in recent virus definition update, , not protected new viruses (see zero-day attack ).
a second method find viruses use heuristic algorithm based on common virus behaviors. method has ability detect new viruses antivirus security firms have yet define signature , gives rise more false positives using signatures. false positives can disruptive, in commercial environment, because may lead company instructing staff not use company computer system until services has checked system viruses. can slow down productivity regular workers.
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