What is a Polymorphic Virus?

The Internet is home to a wide variety of digital threats, including standard malware, Trojan horses, ransomware, and more. But polymorphic viruses are among the worst cyber-hazards you need to understand, both so you can avoid them and so you can know when your computer has one.

If you’re not sure what a polymorphic virus is or how it works, read on; we’ll break down the answers to these questions and more.

What is a Polymorphic Virus?

In a nutshell, a polymorphic virus is a type of computer virus that makes many different versions of itself to avoid detection and better infect target computers/devices. It’s right in the name – “poly” means many, so a “polymorphic” virus is one that can take different shapes (or, rather, have different code appearances).

Like other types of malware, polymorphic viruses are harmful, intrusive, and/or destructive. Because they can change or “morph” as their name suggests, polymorphic viruses can be very hard for antivirus programs or firewalls to detect and stop. That’s why polymorphic viruses are popular and commonly used by hackers, identity thieves, and fraudsters.

Examples of Polymorphic Viruses

The first polymorphic virus ever identified was called 1260 or V2PX. It was made in 1990 during a research project by computer researcher Mark Washburn. However, many non-research polymorphic viruses were created as early as 1991.

More recent examples of polymorphic viruses include the Storm Worm. This virus used a backdoor Trojan virus and was first discovered in 2007. It spread through email messages and could turn computer systems or devices into automated tools called “bots.”

Another example of a polymorphic virus was the Virlock family of ransomware viruses, first discovered in 2014. This virus family used randomly generated decryption codes that changed each time the virus executed itself on a new file.

Difference Between Polymorphic and Metamorphic Malware

Polymorphic and metamorphic malware sound similar, but they are distinct types of malicious viruses. The primary difference between polymorphic and metamorphic malware is that polymorphic malware morphs itself to change its code signature. It does this through a variable encryption key. Meanwhile, metamorphic malware changes or rewrites its code without using an encryption key.

Why the difference? Polymorphic malware is much more common. In fact, most malware executables or .exe files are types of polymorphic malware. Metamorphic malware is more complex, more transformative, and more difficult to create. However, it’s also that much tougher for antivirus software or firewalls to detect!

How Does a Polymorphic Virus Work?

Polymorphic viruses work by varying the appearance of their code each time they mutate or morph. However, the basic or target function of a polymorphic virus stays the same each time it mutates.

For instance, a spyware program might be designed as a keylogger program or virus, tracking the keystrokes of the host computer or user. Even if the spyware keylogger program’s signature or code appearance changes, it still does the same thing.

Unfortunately, polymorphic viruses are so dangerous because changing their appearance makes it almost impossible for anti-malware programs to recognize them upfront. Sticking with the above example, if the spyware keylogger program is detected by your anti-malware program, the anti-malware program will only add the signature it detects to its database. If the polymorphic virus changes again, it could slip by your firewall anyway.

To get more specific, polymorphic viruses:

·         Generate encryptions for their codes or signatures

·         Use different encryption keys every time they mutate to further enhance the deception

·         Use mutation engines to change decryption routines each time they infect a new machine

The mutation engines used by polymorphic viruses and their variants are highly sophisticated and complex. As a result, they can create and implement billions of different code strings or decryption routines, making their viruses even harder for anti-malware software to detect and leading to new vulnerabilities. These types of viruses can lead to infected files on any operating system.

How to Detect a Polymorphic Virus

That all said, it is possible to detect polymorphic viruses using certain technologies and methods.

The majority of antivirus firewalls and other cybersecurity products use signature-based detection methods, which polymorphic viruses get around. Newer security technologies, such as machine learning algorithms and application whitelisting software, use behavior-based analytics to detect viruses based on how they operate or how they move between computer systems or files.

Alternatively, machine learning algorithms may use the behavior of unknown programs – plus “static” characteristics like API calls or file names – to successfully identify malicious code as it operates. They may use so-called heuristic scanning, which means that the software looks for crucial or core components that polymorphic viruses must have to work properly. This can help the software prevent a virus from operating or spreading.

However, many of the best ways to detect polymorphic viruses aren’t available to the average consumer. Because of this, it’s best to avoid getting a polymorphic virus in the first place if at all possible.

Best Practices to Prevent a Polymorphic Virus Infection

In most cases, the best practices to prevent polymorphic virus from infecting your computer or mobile device are the same practices used to avoid other types of cyber threats. Here are some examples.

Always Use Up-to-Date Antivirus Software

For starters, make sure that your computer is equipped with antivirus software, including a robust firewall, and that you update that software regularly. Regular antivirus updates are important because the databases those antivirus programs use are also regularly updated; if you don’t download the new virus definitions to your computer, your firewall won’t be able to recognize and stop new malware programs. The best antivirus software to prevent polymorphic viruses utilize application whitelisting technology, not traditional blacklist antivirus.

Don’t Download Suspicious Files

Next, be sure never to download any suspicious files that you don’t trust or whose senders you don’t trust. For instance, if someone emails you a file and you don’t know where it came from, who the sender is, or what the file is about, simply delete it at the earliest opportunity.

Suspicious files are the easiest way for malware programs to get onto your computer or mobile device.

Don’t Open Suspicious Emails

By the same token, avoid opening any suspicious emails entirely. If you get a spam email from a strange email address – especially one that looks like it was made by randomly combining letters and numbers – delete the email immediately and don’t look back. This is also a good way to avoid phishing scams and other cyber threats.

Avoid Insecure Websites

Insecure websites are those that don’t encrypt their traffic to or from their host servers. Avoid insecure websites whenever possible. You can tell if a website is properly secured by looking for the padlock symbol in the address bar. This indicates the website is protected by SSL encryption and has SSL certification.

Run Regular Antivirus Scans

Lastly, boot up your antivirus program at least once per week and allow it to run a comprehensive virus scan on your computer or mobile device. That’s the best way to catch any malware programs that may have slipped through the cracks of your firewall.

Even though polymorphic malware is difficult to detect and stop, it’s not impossible. Every time you scan your computer, you give your antivirus software another chance to catch the virus and eliminate it entirely. It may be wise to download anti-malware-specific applications like PC Matic, which specialize in preventing malware viruses, like polymorphic viruses, before they can even infect your PC.

Wrap Up

Polymorphic viruses are modern digital hazards that can be very difficult for traditional blacklist antivirus software to detect. However, you can keep your devices and computers safe by following good cyber hygiene best practices, using application whitelisting software, and keeping abreast of new anti-malware measures. Keep your security software updated, avoid insecure websites, and don’t download any files that you don’t trust. With a little luck, you’ll avoid ever encountering a polymorphic virus on your home computer.

Stop Responding to Threats.
Prevent Them.

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