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What is a Zero-Day Attack and How Can You Prevent One?

Lines of code on a laptop screen.

There are many ways a business's security can be breached, and it's the company's job to protect itself from these threats. This is important not only to meet legal requirements but also to keep their staff, customers, and private data safe. One of the most common and hardest security issues to defend against is a zero-day attack. So, what is a zero-day attack, and how can it be used against a business?


What is a zero-day attack?

The term "Zero-day" is widely used to refer to newly uncovered security loopholes that cybercriminals can exploit to attack systems. The phrase "zero-day" signifies that the software developer or vendor has just become aware of the vulnerability, thus having "zero days" to rectify it. A zero-day attack occurs when cybercriminals manipulate the vulnerability before the developers have a chance to fix it.

The term Zero-day is often used in conjunction with words like vulnerability, exploit, and attack, each having distinct meanings:

  • A zero-day vulnerability is a software flaw that attackers discover before the software vendor does. Since the vendors are unaware, no fixes or patches exist for these vulnerabilities, making them an easy target for successful attacks.
  • A zero-day exploit refers to the technique used by hackers to attack systems that harbour an unknown vulnerability.
  • A zero-day attack denotes the utilization of a zero-day exploit to inflict harm on a system or steal data from a system that has a vulnerability.


What causes a zero-day attack and how do they occur?

Even the most meticulously crafted software can have hidden vulnerabilities - unintentional flaws or 'holes' that could potentially be exploited.

Now, our hardworking software programmers are always on the hunt for these sneaky vulnerabilities. When they stumble upon one, they roll up their sleeves, analyze the flaw, and get to work on creating a 'patch'. This is essentially a solution or a fix that seals up the vulnerability. Once ready, they release this patch in a new version of the software.

But here's the catch: this process isn't instant. The moment a flaw is discovered, hackers worldwide can start trying to exploit it. In this race against time, developers have zero days to find a solution – hence the term "zero-day vulnerability". 

The exploit code may result in users of the software falling prey to various forms of cybercrime, such as identity theft. Once a zero-day vulnerability is spotted by attackers, they need an avenue to access the compromised system. This is usually done through a well-crafted email that appears to be from a trusted or legitimate source but is, in fact, from the attacker. The message attempts to persuade the user to perform an action like opening a file or clicking on a link to a harmful website. Doing this causes the attacker's malicious software to be downloaded, which then infiltrates the user's files and accesses sensitive data.

When a vulnerability is detected, developers rush to fix it to halt the attack. However, security flaws often go unnoticed for a while. It can take days, weeks, or even months for developers to spot the vulnerability that led to the attack. Furthermore, even when a patch for a zero-day vulnerability is released, not all users are prompted to apply it. In recent times, hackers have become quicker at exploiting vulnerabilities shortly after they're discovered.

Exploits can fetch high prices on the dark web. Once such an exploit is found and fixed, it's no longer called a zero-day threat.

Zero-day attacks are particularly risky because the only ones aware of them are the attackers. After they've breached a network, these criminals have the option to either strike right away or bide their time until the most opportune moment arises for the attack.


How can you prevent zero-day attacks?

It's all well and good to know what a zero-day attack is, but how can you prevent one from happening to you? Here are a few things that you should be doing:

  • Stay Updated: Keep all your software and operating systems up to date. We all dread the exhausting Windows Updates and other software patches, but these are absolutely essential in patching out any newly discovered software or operating system vulnerabilities.
  • Less is More: The fewer applications you use, the fewer potential trap doors for hackers to exploit. So try to stick to only the essential apps wherever possible. For IT admins, this also impacts patching schedules and imaging. Only deploy the essential apps on a user basis to reduce patching per device. And lock down user access to install new applications.
  • Protect your endpoints: In the case that the worst happens, you need strong endpoint protection tools to protect your data. Make sure every endpoint is running a prevention tool, EDR, and firewall.
  • Educate your users: Within organizations, it's crucial to educate users. Many zero-day attacks capitalise on human error. By teaching good safety and security habits, we can help keep everyone safe online and shield our organizations from zero-day exploits and other digital dangers.

So, are you ready to shield your organization from potential zero-day attacks? Remember, staying informed, keeping your systems updated, and employing additional security measures can make all the difference. Most importantly, your people can become your strongest defence if they're made into cyber awareness superstars with a robust training and human risk management plan in place.


How at risk are you? Get a free risk report

Do you know how at risk your people are to your business? How many data breaches have occurred recently? Which users are likely to fall for phishing simulations? Get in touch if you want to uncover your level of human risk with our free Human Risk Report.