What Are Zero-Day Attacks?

What Are Zero-Day Attacks?
Aviva Zacks
Posted: August 30, 2018

Software is everywhere—in banks, in schools, in hospitals, and in our homes—and advancements in technology have certainly made our lives easier. We use software to access our bank accounts, book our flights, and share photos with friends and family. Unfortunately, software frequently has flaws that leave it vulnerable to malicious hacking.

Hackers exploit software flaws to gain unauthorized access to confidential data; they may even target the hardware itself. They often write code that targets a specific security weakness and create exploitive malware, a type of malicious software that is designed with a particular software vulnerability in mind. This malware is then used to compromise computer systems and steal data, often causing unintended behaviors and damaging the affected systems.

If your computer is infected, hackers can steal your data and take over your computer. With the profusion of eCommerce, online banking, and other high-profile applications of software, we must protect ourselves against digital threats. Here is what you should know about zero-day attacks and how you can protect yourself.

Zero-Day Vulnerabilities Explained

When it comes to software design and coding, human mistakes are not rare. In fact, software may do things the developer didn’t intend and couldn’t even predict.

Quite often, these “software bugs” are discovered by the developers themselves and promptly fixed. But not all bugs are created equal. While some bugs are nothing more than minor hiccups, others can have far-reaching consequences.

Hackers are constantly looking for vulnerabilities that they can exploit. Last year, a highly publicized ransomware attack, WannaCry, paralyzed over 300,000 PCs worldwide by using EternalBlue, an exploit developed by the U.S. National Security Agency (NSA). The attack caused widespread damage at the time, but smaller scale attacks are still happening every single day.

When new software is released, there can be security issues that neither the vendor nor the antivirus companies are aware of. Until the vendor or cybersecurity professionals find the problem and release a software update that fixes the issue, this bug is known as a zero-day vulnerability or a zero-day exploit.

Once the cybersecurity community learns of the exploit, they will release an update, or a “patch” that solves the problem. However, it can take months to find a security flaw, giving malicious actors plenty of time to cause severe damage.

Personal data is a valuable commodity that can be sold online. Therefore, if a malicious hacker finds a bug before a patch is released, they will try to exploit it to gain access to data and systems. As selling data becomes more profitable, the frequency and sophistication of attacks will continue to rise.

But some antivirus solutions can detect zero-day attacks with the help of advanced techniques such as behavior-tracking algorithms that find suspicious or malicious behavior on your system.

How to Protect Yourself Against Zero-Day Attacks

As software systems become more complicated, so does the task of securing them. That means enterprising hackers may have an even greater opportunity to break into those systems successfully.

Bugs in software are inevitable, but it doesn’t mean that we can’t fight back. There are many great cybersecurity vendors and robust solutions out there. In fact, most attacks—including those that exploit zero-day vulnerabilities—can be avoided through best practices like patching your system and installing zero-day antivirus applications.

How Zero-Day Antivirus Solutions Can Protect You

Antivirus solutions were initially created to deal with viruses, however as the threat landscape evolved, so did the software to fight it. Most modern antivirus software is designed to detect, prevent, and disarm malicious software with the help of advanced detection techniques.

Zero-day antivirus software is capable of identifying known and unknown malicious files. The goal is to block them before they can cause damage to your computer or steal your data.

Signature-based detection

A virus signature is a unique pattern or code that can be used to detect and identify specific viruses. The antivirus scans file signatures and compares them to a database of known malicious codes. If they match, the file is flagged and treated as a threat.

The major limitation of signature-based detection is that it is only capable of flagging already known malware, making it completely useless against zero-day attacks.

Zero-day attacks are increasingly prevalent, and cybercriminals manage to release unique malware that remains undetected for weeks or even months. According to a report by WatchGuard, at least 30 percent of malware today is new, zero-day malware that is missed by traditional antivirus defenses.

Relying on antivirus signatures is simply not enough. Even worse, attackers frequently program malware to mutate and alter its signature in order to avoid detection. The ability to automatically morph their malware has outpaced the cybersecurity industry’s ability to keep up with new signatures.

Heuristics-based detection

As the effectiveness of signature-based techniques diminishes, antivirus solutions have turned to “heuristic” techniques to identify malware. Heuristics-based detection does not require an exact signature match. Instead, it detects potential malware by examining files for suspicious characteristics.

However, heuristics-based detection has a drawback, namely that it can inadvertently flag legitimate files as malicious, causing trouble in the systems it was designed to protect.

Zero-Day Antivirus and Behavior-Based Detection

Once malware has been identified by experts, dealing with it is an easy task for your antivirus. But when it comes to zero-day threats, signature-based and heuristics detection techniques no longer cut it.

Fortunately, quite a few antivirus products have advanced capabilities that enable them to fight off zero-day attacks effectively. Detecting malware via behavior analysis is gaining traction, and the best antivirus solutions are deploying this technique.

Behavioral detection looks for malicious malware by logging suspicious patterns of behavior to identify the malware. Observing behaviors rather than the signatures allows antivirus software to seek out undetected malware and effectively fight off zero-day attacks.


The best antivirus solutions combine both signature and behavior analysis approaches. Fortunately, to keep up with malware, antivirus developers incorporate multiple layers into their tools. As a result, zero-day antivirus solutions are capable of fending off even the most advanced attacks.

Installing a strong antivirus tool that takes advantages of the latest cybersecurity developments can mean being protected from a threat instead of leaving your system exposed.