Zero-day attacks -what they are, how they work, and how to stay protected

A zero-day exploit is malicious code that takes advantage of a software flaw unknown to the vendor. Because the flaw hasn’t been patched, attackers can use it immediately, often before security teams even know it exists.

A zero-day attack occurs when hackers use a zero-day exploit to compromise a system. They may deliver it via emails, websites, or downloads, and once successful, it can install malware, steal data, or open backdoors for future access.

They usually happen right after a vulnerability is discovered by attackers but before the vendor issues a fix. The window between discovery and patch release is the most dangerous, as users remain unprotected.

Zero-day vulnerabilities are especially dangerous because they’re unknown to both software vendors and users, leaving systems exposed before a fix is available. Traditional defenses often fail to detect them, giving attackers a head start to exploit flaws undetected. These hidden threats highlight the importance of strong cybersecurity practices, including real-time protection and regular software updates to minimize exposure.

Both. Ethical security researchers sometimes find flaws and report them responsibly. Hackers may also discover vulnerabilities, but instead of reporting them, they use them in attacks or sell them on the dark web.

Hackers analyze software code and test for weaknesses. Once they find a flaw, they create an exploit and distribute it via phishing emails, malware downloads, or compromised websites. Some attackers sell these exploits to other criminals.

Examples include the Stuxnet worm in 2010, the WannaCry ransomware outbreak in 2017, Microsoft Exchange server attacks in 2021, and the MOVEit Transfer breach in 2023. Each example shows the devastating potential of zero-days.

Yes. Modern antivirus solutions use real-time monitoring to detect unusual or suspicious activity, even from previously unknown malware. This allows them to block zero-day exploits based on behavior rather than relying solely on known signatures. Intego Antivirus provides advanced real-time protection that helps identify and stop zero-day threats before they can compromise your system.

The best defense against zero-day exploits is a layered security approach: use reliable antivirus software, keep your system and apps updated, and enable a strong firewall. Intego Firewall helps protect your computer by monitoring network activity and blocking suspicious or unauthorized connections, adding a powerful layer of protection against unknown threats. Practicing safe browsing further reduces your overall risk.

A zero-day exploit targets a flaw that has not been patched or disclosed. A known vulnerability is one that vendors and users are aware of, with patches or updates available. Zero-days are therefore riskier because no fix exists yet.