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What Is Zero-Day Vulnerability? All You Need to Know

Adrian Marszalek 74580312c1

06/04/2022 |

5 min read

Adrian Marszałek

Software weaknesses and zero-day vulnerability are something that gives many IT professionals and business owners a headache. Undoubtedly, zero-day is one of the key terms that any cybersecurity personnel knows and it can keep CISOs awake at night.

It means that a specific new vulnerability in a piece of software (virtually any kind of software) has been found and the publisher has not created any patch for it, yet. In other words - we know that there is a hole in the wall but we need to wait for the construction worker to fix it. We know it should happen soon, but in the meantime, we are vulnerable to trespassers who can locate that hole. And this may have grave consequences.

But there are some other cybersecurity terms, related to 0-day vulnerability, such as a zero-day exploit, and zero-day attacks. In this article, we’ll shed light on them, too, as well as on what steps should be taken to avoid them and to become more resistant to potential threats of that kind.


Table of contents:


Zero-day vulnerability and exploit in a nutshell

But what is a zero-day vulnerability, in brief? And what is a zero-day exploit? 

Well, in short, zero-day vulnerability may be defined as a flaw occurring in software or hardware (an operating system, program, browser, or a device) that has been identified but not fixed, yet. If cybercriminals take advantage of it and perform a zero-day attack, a zero-day exploit takes place.

What’s crucial about 0-day vulnerability is finding the way to identify it fast enough. The zero-day is usually discovered through reverse engineering, probing the software with some (non-intended by its producer) uses and repeating patterns of exploitation of already known vulnerabilities (that may already be patched) in software with similar architecture.

However, many companies actually pay hackers for finding 0day vulnerabilities (and creating exploits). We are talking about thousands or tens of thousands of Euros for critical security vulnerabilities found during that process. It usually works in a sanctioned, safe way where a given company announces bug bounty, providing specific rules of engagement like project scope, and reward rules.

Unfortunately, there are also “zero-day brokers” operating on a black market that buy out critical zero-days and its exploits for up to millions of dollars worth in compensation. This can create a major ethical dilemma for any professional involved in bug bounties activities.

How to avoid and tackle zero-day exploits and vulnerabilities – best practices

Of course, spotting zero-day vulnerabilities requires determined and rapid actions. Generally speaking, software publishers who become aware of some zero-day vulnerability take one of the two paths. These practices include:

  1. Making that information public – Usually, this message comes with an estimate of when the vulnerability can be patched and some possible workarounds for the time being. However, that carries an obvious risk that if there are any hackers that have not familiarized themselves with it, yet, it will definitely point them in that direction. Still, many companies decide to take that path because it allows cybersecurity professionals to act on the vulnerability and use some preventive measures before the vulnerability gets patched.
  2. No information is made public until a patch is ready – This approach can limit the possibility of widespread exposure to the software vulnerability. The risk associated with this approach is that many malicious hackers share zero-day information with each other. Also, security professionals may not have been informed about the compromise possibility through a zero-day vulnerability.

No matter which path is chosen, there is a chance that the information about zero-day vulnerability gets identified. That means that there will be some people working on creating a malicious piece of software that will actually exploit that vulnerability in order to gain unauthorized access or conduct other malicious activity resulting in compromising the unpatched software.

That malicious software created for that purpose may also be called the "zero-day exploit". This is the moment that the actual race to fix the vulnerability becomes more tense. Without the exploit, it usually requires substantial knowledge to put the unknown vulnerability to good use. With the exploit - it becomes more accessible for the hackers.

Zero-day exploit and vulnerability – things to remember

Normally, I would put some general summary of the topic here, but I hope it should become already quite obvious that it is crucial to keep your software updated at all times. 

Any unpatched vulnerability can virtually keep its "zero-day" status in your network for as long as it's not taken care of. And this might leave your assets exposed for a potential cyberattack. Of course, the more this exposition lasts, the worse. To save the day, you have to act fast and get the builders immediately to patch the hole that had been identified.

Anyway, the zero-day issue is vital, as is assuring security in the whole IT industry and the computing areas in all businesses. Keeping track of the newest safety measures, as well as of potential threats should be a golden rule in every case. Although such prevention may be expensive, the consequences of sensitive data breaches, leaks, and cybercrimes are often far more costly.

To protect valuable business data, you need to know how zero-day attacks work as well as how to avoid a 0day exploit and how not to overlook any vulnerabilities. Because, sooner or later, a vulnerable system will surely bring you trouble, unless security patches are introduced fast. It’s definitely worth making the effort as zero-day protection is undoubtedly one of the most important pieces of the cybersecurity puzzle.

If you want to avoid zero-day vulnerability but don’t know what to start with or need any kind of professional assistance in the process of safeguarding your IT resources, contact us now.

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Adrian Marszalek 74580312c1

Adrian Marszałek

Cybersecurity geek specializing in offensive cybersecurity (penetration testing) as well as physical penetration testing (controlled non-destructive break-ins into premises). In spare time amateur wildlife photographer.

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