Antivirus products have databases of previously discovered malware signatures. Whenever a file is found to be a match, it’s then deleted before it can do any damage.
One popular solution to this problem is polymorphism which involves making small changes to malware files to avoid detection.
So, what exactly is polymorphic malware, and how can you protect your computer from it? Let’s have a look.
What Is Polymorphism?
The term “polymorphism” was originally established in biology. It is defined as the condition of occurring in several different forms.
It is now an important concept in computer science. When used in programming, it means the provision of a single interface to multiple different types.
What Is Polymorphic Malware?
Polymorphic malware utilizes the concept of polymorphism not for efficiency but rather for the purpose of evading detection.
The idea behind polymorphic malware is that if a particular malware strain is known for having certain properties, then new versions of that malware can avoid detection if slight changes are made.
This allows endless malware files, which all perform the same function, to appear sufficiently unique that they are not recognized as malware.
Polymorphic malware is not a new concept. It’s thought to have been invented in the 1980s. Despite this fact, it’s heavily used today—and most strains of malware have polymorphic behavior.
The reason for its continued popularity is simple—it remains effective, even though defenses against malware have improved. As long as antivirus software continues to detect malware based on signatures, polymorphism will be used as a disguise.
It is also not limited to a specific type of malware. Polymorphic code has been found in trojans, rootkits, ransomware, and keyloggers.
How Does Polymorphic Malware Work?
Polymorphic code is typically used to produce malware that mutates much faster than antivirus engines can identify it. Some of the fastest examples change every 15-20 seconds.
This means that it doesn’t matter how many antivirus engines record a particular file. By the time they start blocking it, new examples of the same file will not be flagged.
While regular malware would be deleted or moved to quarantine, polymorphic malware is instead allowed to run.
If the person using the infected computer doesn’t recognize the signs of malware infection, the malware will be allowed to run indefinitely.
Polymorphic vs. Metamorphic Malware: What’s the Difference?
The terms polymorphic and metamorphic malware are often used interchangeably. This is because they both utilize mutation to avoid detection by signature-based antivirus.
There is, however, an important difference between the two. While polymorphic changes some of its code every time it’s copied, metamorphic malware changes all of its code. This makes metaphoric malware significantly more effective.
The catch is that it’s also significantly harder to create as it relies on so many different transformation techniques.
Who Is Targeted by Polymorphic Malware?
The most sophisticated hacking attempts are typically reserved for businesses and other high-value targets.
Polymorphic malware is harder to develop than traditional malware, but it’s still cheap to launch in scale. This means that while businesses should be particularly worried, polymorphic malware is used to target all computer users.
What Does Polymorphic Malware Do?
Polymorphic code has been found in all types of malware. This means that it can be used for:
Ransomware that encrypts your files and asks for a ransom payment in exchange for their return. Keyloggers that record your keystrokes for the purpose of stealing your passwords. Rootkits that provide remote access to your computer. Browser manipulation that redirects your browser to malicious websites. Adware that slows down your computer and advertises questionable products.
How to Protect Against Polymorphic Malware
Polymorphic malware is significantly better at avoiding antivirus detection. Despite this fact, many antivirus products do still detect it—and even if they don’t, there are other ways to protect against it. Below are a few examples.
Use Heuristic Antivirus
Heuristic antivirus uses signatures to detect malware, but instead of looking for files that match known malware samples, it looks for files that have similar components to known malware. This allows it to recognize malware files even after significant changes have been made to their structure.
Use Behavioral Antivirus
Some antivirus products, but not all, monitor your computer and identify malware by watching how programs behave. For example, if a program starts recording your keystrokes, then it’s probably a keylogger regardless of whether or not it has a known malware signature. This type of antivirus will usually identify polymorphic malware.
Keep Your Software Updated
Many types of malware are designed to take advantage of known vulnerabilities in popular software products. These vulnerabilities can be removed from the programs on your computer by performing regular software updates. This means that if polymorphic malware is on your computer, it won’t be able to do as much damage.
Recognize Malware Yourself
Regardless of how malware is developed, if it starts running, it will often cause your computer to behave in certain ways. For example, you might notice that:
Your computer is noticeably slower. You see a sudden increase in advertising. Your browser starts sending you to pages that you didn’t request. Your computer starts displaying unusual messages.
If you notice any of these things happening on your computer, you should suspect malware and take steps to remove it.
Use the Internet Responsibly
All malware, including polymorphic malware, only infects a computer if the person using that computer does something wrong. If you’re worried about polymorphic malware, the easiest way to prevent it is to be careful what websites you visit, the email attachments you open, and the files you download.
Is Polymorphic Malware a Problem?
Polymorphic malware is an ongoing cybersecurity threat. Even though there’s nothing new about it, it remains a popular anti-detection technique. This is also unlikely to change provided AV software continues to use signature-based detection.
The easiest way to protect against polymorphic malware is to use behavioral antivirus software and to use the internet responsibly to prevent it from being downloaded in the first place.
