Why is polymorphic malware better than metamorphic malware?

  • deepti

  • Jan. 21, 2021, 9:35 a.m.

Imagine a malicious entity or virus that can change and modify over time. This shapeshifter camouflages itself by adjusting its "genetic makeup," its code to conceal itself from those who are trying to destroy it. Sadly, this situation is not just something that you need to think up. While it may sound like something from a science fiction novel, in the world of IT security, polymorphic malware is all too true.

Polymorphic malware is more common than most people realize. Webroot's latest analysis found that "more than 94% of all malicious executables we encounter are polymorphic." Webroot recognizes that the prevalence of malware and potentially unwanted applications have increased dramatically.

Polymorphic malware has an even more unattractive and unpleasant parent who is even harder to find. Due to its greater complexity and transformative capabilities, metamorphic malware can evade more traditional methods of detection than polymorphic malware.

1. What is Polymorphic malware?

Have you ever seen a chameleon change its colors to the background to blend in? It is bright green one minute, and practically invisible the next, just part of the dirt and rocks! This is a prime example of polymorphism. In cybersecurity, however, there is a less optimistic connotation to the word polymorphism. In this sense, polymorphic refers to the ability of malware to modify and adjust its features continuously to avoid detection.

Polymorphic malware exists as viruses, bots, trojans, worms, and keyloggers. Regardless of the type, its sophistication and speed are what make this malware so effective. Polymorphic malware changes rapidly - as frequently as every 15-20 seconds using polymorphic code.

Employee ignorance and unrecognized zero-day vulnerabilities are abused by polymorphic malware to wreak havoc. When an employee clicks on a phishing email attachment or provides information through a phishing website, they open up to attack your entire network, company, and sensitive data. And it is harder to define let alone eradicate as the threat is constantly changing.

2. What is Metamorphic malware?

Metamorphic malware reprograms itself. It translates the code on its own and produces a temporary representation. Then, the temporary representation is modified and written back to the usual code. In other words, it translates its own code and rewrites it so that the copies of the virus appear different each time.

Much like in the case of polymorphic viruses, a metamorphic virus does not use a key encryption method. When a new copy of itself is produced by the virus, it transforms its present instructions into functionally equivalent instructions. Therefore, no part of the virus remains constant and during the execution, the virus will not return to its original form. Therefore, it makes it impossible for the anti-virus and cybersecurity software tools to identify it. Geometric detection and the use of tracing emulators are two ways to detect metamorphic malware.

3. Polymorphic Malware vs Metamorphic Malware


People always assume that polymorphic malware and metamorphic malware are the same, and they are on the surface: they are adaptive and mutating software used by hackers to penetrate and steal data while escaping detection. And both polymorphic and metamorphic malware are targeted at circumventing conventional solutions to anti-malware. However, while their objectives are the same, the way they are achieved by each form of malware varies, making malware analysis difficult.

One thing that differentiates metamorphic from polymorphic malware is that it rewrites the code entirely so that its previous iteration is no longer matched by each newly propagated version of itself. This is distinct from polymorphic malware, which modifies part of its code but maintains one section of its code that remains the same.

It is considered to be more difficult to write a metamorphic virus than a polymorphic virus. Multiple transformation methods must be used by the programmer.

Detection techniques are another significant distinction between polymorphic and metamorphic viruses. Polymorphic viruses are detected using the Entry Point Algorithm and the Generic Description Technology. Metamorphic Viruses can be detected using Geometric detection and emulators for tracing.


The main distinction between polymorphic and metamorphic viruses is that a variable encryption key is used to encrypt the polymorphic virus so that each copy of the virus appears different. The metamorphic virus rewrites its code on its own so that each copy of the virus appears different without a variable encryption key being used. Both of them are difficult to identify using the regular antivirus programs and malware analysis software.

REVERSS is a dynamic malware analysis tool provided by Anlyz. This advanced malware analysis tool uses reverse engineering techniques to provide real-time analytics and protect your system against cyber threats. Know more about the features of REVERSS.

Exploring Cybersecurity solutions?
Get secure with Anlyz