How Does Antivirus Software Work?

How Does Antivirus Software Work? - Post Thumbnail
This article is aimed at regular users that want to learn more about antivirus software and how it works. We’ll go over such topics as various virus detection methods, antivirus activity in the background, and regular scans. We’ll also answer the question: should you launch scans manually or not? No desktop computer/mobile device is safe unless there’s some antivirus protection installed on the OS. It’s important to note that even the best antivirus software can’t be the only solution against malware. However, it is an essential component, one that has access to a vast database of known malicious files. This database is being updated in real time and allows it to block any suspicious files successfully. It happens before they make their way onto the user’s device and hurt it in any way.

Real-Time Protection

Here’s how an antivirus product works: it runs in the background, continually checking every single file/folder the user opens. This process is described as real-time protection, on-access scanning, and background scanning. In this mode, it has a very light impact on the system resources (CPU and RAM). When the user clicks on an EXE file, it may seem like it launches itself that very moment, but that’s not what happens. Before allowing self-execution of any file, the antivirus checks it first. It only requires a second to cross-reference the database and compare it to known types of malware. Furthermore, it also performs so-called “heuristic” checking. That’s when it carefully and closely monitors apps and files, trying to recognize patterns of bad behavior.
Antivirus products scan all types of files/folders that may carry malicious code. Did you know that .zip archives can also contain “masked,” compressed viruses? Even Word documents may hide a malicious macro, and there’s no way of knowing it unless you have an antivirus on your OS. These types of potentially dangerous files are always under surveillance: whenever you download an EXE file, the antivirus will check it immediately. On-access scanning is one of the most useful tools against viruses. Without it, malware will be able to exploit security holes and stay undetected for a very long time. Remember: once a virus successfully infects the operating system, it becomes much harder to find and terminate it. In some cases, the user can’t be 100% sure that the virus has gone for good.

Should You Run a Full Scan?

We just discussed real-time scanning, and because of it, you don’t have to run manual scans very often. Whenever you download something malicious to your device, the best antivirus software detects it immediately. Again, that means the user isn’t required to scan any file/folder he/she downloads manually. Still, there are some situations when a full system scan is necessary. For example, it is highly recommended to initiate such a scan after installing a new antivirus product. The full scan will make sure there are no hidden viruses on your device. Modern-day antiviruses launch scheduled system scans without bothering the user. Since the virus database is continuously being updated, these regular scans ensure the safety of your OS. Full scans can also be helpful when you’re trying to fix a desktop computer. If it’s taken over my malicious files, connecting the hard drive to another computer might help. Running a full scan from there can help you “heal” the hard drive. Other than that, manually-launched scans aren’t necessary, as antivirus products do it automatically.

Virus Detection Techniques

Now that we’ve discussed the basics, let us go ahead and take a quick look at the various virus detection techniques that antivirus products use:
  • Signature-based detection. This technique takes into consideration critical aspects of a suspicious file to create a static fingerprint (like a line-up of bytes in a file). A cryptographic hash of this file/some of its sectors can also be used. This is the oldest virus-detection method, and, to this day, it’s quite capable. The biggest downside of signature-based detection is that it’s useless against new malware without signatures in the database.
  • Heuristics-based detection. In contrast to the previous technique, this one doesn’t require an exact match of malware signature. Heuristics-based detection examines the file for signs of unknown/rare instructions/junk code. It runs safe emulations to check what the potentially dangerous file would do when launched.
Important note: one single suspicious element might not trigger the antivirus, but multiple factors will. The downside – legitimate, 100% safe files might also be flagged.
  • Behavioral detection. Instead of emulating the execution of the malicious file, this tool checks its behavior in real time. If the file is caught modifying data on the OS, or unpacking malicious code, Behavioral will instantly detect its malicious origin. Any attempts at accessing keystrokes will also be recognized as malicious activity. This method is excellent for identifying dangerous files that could’ve gone unnoticed.
Again, behavioral detection works similar to heuristics. A single suspicious activity won’t trigger this tool, but multiple actions will activate it.
  • Cloud-based detection. This type of detection takes advantage of the large antivirus database we mentioned earlier. Instead of analyzing everything locally, it takes notes from computers worldwide and lets the cloud engine do all the work. All the antivirus does in this scenario is collecting relevant data about the suspicious file and sending it all to the “HQ.”
cloud based detection
The cloud engine, in turn, uses of all the available data from various computers/mobile devices. Compared to a single antivirus doing local observations, this technique is much more effective. Cloud-based detection gathers experiences and notes from every single device in the community and puts all that knowledge to good use. Fact: while we separated the four detection methods above, they aren’t that different from each other. Also, most users and even experts use the terms “Behavioral” and “Heuristics-based” to describe the same tools. Besides, contemporary antivirus products use all of these techniques together. That’s especially true for cloud-based detection. Generally, all these methods are active at the same time, working together towards a mutual goal. Malware is evolving at an impressive rate, becoming harder to track and eliminate. To protect users from the ever-growing threat, antiviruses use as many protection layers as possible. One single tool can no longer be effective against viruses.

How Is the Webroot Detection System Different?

WSA (Webroot SecureAnywhere review) is a highly capable antivirus product that takes a different approach. According to our experts, it features one of the most effective security protocols on the market. It uses a brand-new method of malware detection, one that allows it to prevail. It is important to note that traditional lab tests (including the hands-on approach) aren’t fit for this antivirus. Because it uses a significantly different technique for identifying malware, traditional tests don’t reveal its full potential. Webroot doesn’t use the signature database method. Instead, it continually monitors behavioral patterns and metadata. Once an unknown program is found, the antivirus immediately starts to log its behavior.
Webroot quarantine
Sometimes, a human expert takes over and examines the suspicious files/programs. So it’s up to them to determine whether they are dangerous or not and what to do with them. Just like the regular antivirus solutions, Webroot collects and analyzes data. However, instead of acting, it lets the cloud computer decide what to do with it. Yes, this isn’t a traditional approach, but tests prove that it’s quite capable. The industry needs some time to process and understand this technique fully.

False Positives

Antivirus products aren’t ideal – that’s a given. They are doing a great job of detecting dangerous files and eliminating them, but, they aren’t without flaws. The term “false positives” refers to a situation when an antivirus identifies a 100% safe and harmless file as malware. In some cases, it fails at recognizing critical Windows files and puts them in quarantine, thus making the system unstable. Sometimes, 3rd-party apps/clients are mistaken for malware and treated as threats. Thankfully, this happens very rarely and usually ends up on the news. For example, an older version of AVG used to damage Windows 7, while Microsoft’s built-in antivirus identified Google as a virus once. Even the antivirus’s files can end up being quarantined. Heuristics are also known to cause trouble. The tool may detect some suspicious activity and identify a file or a group of files as malware. But, again, false positives only happen once in a lifetime. So, when your antivirus detects a file/program as dangerous, it would be wise to believe its judgment.

Bottom Line

This is it for our guide on how modern-day antivirus products detect and eliminate malicious threats online. Our goal was not to answer the question – what is the best antivirus software – but rather to reveal some of the tools antiviruses use. True, a user doesn’t need to know any of it, as the software does everything on its own. Still, if you want to know at least the basics of how it all works, this post will be a great way to start.