Antivirus protection software is designed to prevent, detect, and help remove threats from computer systems. These threats take the form of software viruses and other malware such as ransomware, worms, Trojans, and adware.
A computer virus is software, loaded onto a computer without the user's knowledge, that performs malicious actions.
Once loaded onto a computer system, a virus can self-replicate and insert itself into other programs or files, infecting them in the process. Typically, all viruses are destructive in some manner. Ransomware --one example of malicious software--is designed by adversaries to infect and disable computer systems for the purpose of financial gain.
Antivirus protection software can help defend against computer viruses. Key tasks it performs to protect against these attacks include:
Traditional antivirus software relies heavily upon the signature, or binary pattern, of a virus to identify malware. Antivirus security vendors analyze files suspected of containing malware and once it is determined to be malicious, a proper signature of the file is extracted and added to the signatures database for the antivirus software.
Unfortunately, traditional antivirus protection is really only detecting common malware and is mostly ineffective against more modern viruses. Most adversaries (malware authors) stay a step ahead of such software by writing "oligomorphic," "polymorphic," and more recently "metamorphic" viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so as to not match virus signatures in the antivirus database.
Around 2013, the security industry's focus shifted toward signature-less approaches to antivirus protection. New antivirus capabilities were developed to detect and mitigate zero-day attacks and other, more sophisticated malware. Some of these next-generation capabilities include:
These more effective methods are found in next-generation, endpoint detection and response (EDR) and--more recently--extended detection and response (XDR) solutions.