What is Zero Day Attack?

When an unknown vulnerability in software is exploited, it is called a Zero Day Attack. It is sometimes referred as a Zero-Hour, 0-day or day-zero attack.

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Software developers release their product for end-users only after vigorous testing has been completed. But of course, the phrase “nothing is perfect” applies to software programs too. There are always unforeseen flaws that might be related to some functionality problems, features, spelling mistakes or a security hole.

To resolve these issues, the developer subsequently releases updates. They might be reported by users or discovered by self-testing. If the developer himself discovers any security hole, that is fine. However, when a software vulnerability is discovered by criminally-inclined people, it can be exploited for nefarious purposes.

Security holes can be used for gaining illegal access to a user’s system, injecting malware or taking control of user’s computer remotely.

This kind of security flaw, which is unknown to the developer, is called a zero-day vulnerability.

There is no immediate fix available for such a vulnerability, as the developer was unaware of its existence.

Attackers exploit these vulnerabilities by various means. Web browsers and software like Java and Flash are more vulnerable. So, attackers might locate unsecured users through email attachments or software bundles.

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Zero Day Attacks occur within a specific time frame, known as a vulnerability window. This is the time beginning from the first vulnerability exploit to the point at which a threat is countered.

Zero Day Attacks are strategically implemented to cause maximum damage within a short span of time.

How Dangerous are Zero Day Attacks?

I hope now you realize the importance of preventing a zero-day vulnerability. Tech companies are offering to pay such huge amounts of money just to discover a vulnerability in their own software.

That’s because if exploited, they are worth millions of dollars.

There are companies like Revuln that research software vulnerabilities and sell the results to third parties instead of reporting them to the affected vendor. Some Zero Day exploits are even bought online by companies like Zerodium (which specializes in iOS exploits).

Examples Of Zero Day Attack Exploits

Recently, Google disclosed a vulnerability in Windows which allowed hackers to steal information from memory. This flaw has yet to be fixed by Microsoft even though it has been disclosed to the public – including hackers.

In 2008, there was another instance in which Microsoft revealed a vulnerability in Internet Explorer after 7 years of exposure.

Apart from operating systems, Java and Flash are the two most exploited software products. This is the reason they receive continuous updates and patches.

Zero Day Attacks can strike against video game systems too. Researchers found zero-day vulnerabilities to exploit game engines such as CryEngine 3, Unreal Engine 3, id Tech 4 and Hydrogen Engine. (Source)

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How To Protect From A Zero Day Attack

As you know, there are no immediate fixes available to resolve the exploit because the developer is still unaware of its existence.

So, a better approach is to depend on proven anti-malware solutions like MalwareFox.

How will third party software detect vulnerabilities?

This is an important question because how can someone else (who isn’t the developer) detect a flaw in the software?

If you are already using a Layered Security configuration, there is no need to worry.

Others must ensure that they have a Behavioral Blocker installed on their system. It is a unique method of detecting malware by monitoring the behavior of a program. If activity appears to be suspicious, it will be blocked.

Malware often attacks system files and the blocker registers these actions as unauthorized or suspicious. Once such an attempt is detected, the Behavioral Blocker will block execution of that program and thus, the Zero Day Attack is prevented.

MalwareFox has a behavioral blocker integrated into its system and is a proven anti-malware product that safeguards users against Zero-Day Attacks.

If an attack bypasses the behavioral blocker, there is HIPS (Host Intrusion Protection System), which can monitor running activity. It has the ability to stop running the malicious process if a suspicious code is detected.

Not all Zero Day Attacks take place before the developer knows about it. Sometimes it takes time to understand and develop the patch for the vulnerability.

Microsoft, for example has Patch Tuesday when they release a weekly update that includes security patches. It is the reason that we recommend installing critical security updates as soon as they arrive. Alternatively, keep the updates automatic to avoid missing anything.

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Once the patch is released, it is no longer called a Zero Day exploit. The vulnerability is now public and the hackers who did not know about the flaw become aware of it. If you delay updating/installing the patch, you may become the victim of a hacker who is targeting such users.


Zero-day malware is incredibly dangerous for users. As they are unknown in cyberspace, it is unlikely that your Antivirus software will detect it. It is recommended that you install a proven anti-malware solution like MalwareFox, which can detect and remove known – as well as unknown – malware too.

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10 thoughts on “What is Zero Day Attack?”

  1. I’ve heard that term before but it’s the first time that I actually understand what it means, this is a very helpful article.

    • Same here, I’ve seen a lot of tech nerds talking about this but not one of them ever explained what it meant, turns out that it was rather simple to understand.

  2. So, Anti-Malware programs can protect us from zero-day attacks, but what about Antivirus ones? Can they do the same? Is it necessary to have an Anti-Malware?

    • There is another article in this blog which clearly answers your question but oh well, yes you’ll need both an Anti-Malware and an Antivirus. The one covers what the other misses, in this case, zero-day attacks.

    • I think that he is referring to the “Difference between Antivirus and Anti-Malware” article, you should check it out.


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