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Understanding Zero-Day Attacks

zero day attack occurring to a computer software code

The Rise of Zero-Day Exploits and Attacks

Part of forming an effective cybersecurity strategy means understanding the threats that can impact your organization. One form of threat that is on the rise and steadily evolving in complexity and danger is a zero-day attack, also referred to as a zero-day exploit. The name of these malicious assaults is derived from how many days it’s been since a third-party exploit, or it refers to when a company hasn’t had the opportunity to fix a security issue. A prime example of this is the release of new software that is vulnerable to a day-one attack since there hasn’t been time to patch potential problems.

Another example is when a user installs anti-virus software. Generally, the program is an older/basic version of the software that requires updates to protect the system. A zero-day attack/exploit occurs when a cyberattacker compromises the system since it hasn’t updated to its latest protection library. You could also think about the hardware itself; a new computer without installed protections is vulnerable to any form of exploit until it’s updated appropriately.

Typically, there are three general ways to define zero-day threats:

Zero-Day Attacks: This occurs when a third-party exploits vulnerabilities in software. RansomWare is an example.

Zero-Day Exploit: The exploit created from a zero-day attack, or the result from a zero-day attack

Zero-Day Vulnerability: The vulnerability discovered by perpetrators to create their exploit/attack.

These aren’t comfortable scenarios to imagine. On a larger scale, they’re damaging to a business and its infrastructure since an exploit leaves the network open to further exploitation. Additionally, zero-day attacks can routinely catch an enterprise off-guard, causing more damage (this is because a business has to ‘react’ instead of preventing the attack, which we’ll get into later). Without an appropriate response strategy, downtime is guaranteed.

Since  a good cybersecurity strategy involves a proactive approach, instead of reactive, an organization has to “work from behind.” In other words, they have to spend resources and time creating a new security patch versus having proper defenses in place. 

How Does It Occur

Part of developing useful, proactive strategies is to understand how these attacks occur. Third-parties apply a range of techniques to infiltrate systems, and we’ll briefly go over them to provide context on how zero-day exploits are developed.

Analysis and Attack Testing – During the initial stage, perpetrators attempt to locate vulnerabilities in software. This requires an in-depth analysis of the software by observing its source code and typically requires an extensive amount of knowledge on the subject (such as software engineering). Third-parties will deploy a variety of methods to accomplish this, and it’s often where unusual behaviors are discovered.

Fuzz Analysis – Similar to attack testing, fuzz testing occurs when the perpetrator attempts to find vulnerabilities by implementing random values into a system. The process is often automated or tool-assisted. The longer this goes undetected the higher chance a third-party will succeed in their attack.

Creation – Once a malicious-party has discovered suitable entry points and/or vulnerabilities, the zero-day exploitation is created. The malware developed to launch attacks is often incredibly complex and challenging to detect. At this point, it is difficult to prevent a zero-day intrusion.

Implementation and Deployment – After the malware’s development, it’s delivered into a target system. Depending on the complexity, some organizations can remain unaware they have been affected until critical systems are compromised.

What Can You Do

No business wants to feel helpless in the face of a cybersecurity threat. Fortunately, there are several steps you and your organization can take to handle these situations should they occur. This is important, as not all zero-day exploits occur because of a company’s infrastructure. Any kind of software, program, or module used by your business is vulnerable if not patched appropriately.

For instance, imagine your company utilizes universal-communications software. A form of malware is created to target this platform, seeking to steal user information like an employee login. The provider of said software hasn’t patched for this, and a zero-day attack occurs. Until the developer patches the issue, the software either can’t be used or remains vulnerable to dangerous attacks.

To combat these issues, there are several methods to follow when dealing with zero-day attacks.

1. Advanced Monitoring

One potential solution for early detection of a zero-day exploit is monitoring. Monitoring is a catch-all phrase but generally involves software and network infrastructure. The goal is to identify and flag unusual behaviors, such as incoming network traffic or changes in the behavior of an application. Often, an enterprise has to develop its monitoring methods as their infrastructure is unique to them. The idea is to characterize zero-day attacks for detection while working to prevent them in the future.

2. Behavior-Based Detection

Similar to above, detecting zero-day exploits with behavior-based detection involves identifying unusual actions involving a software platform. This involves observing an application and its interaction with files. The idea is to conclude whether or not this behavior is malicious.

3. AI-Based Monitoring/Detection

Since organizations face numerous challenges when attempting to detect day-one exploits, AI-based monitoring is another useful solution. AI and its responsive algorithms are arguably one of the only ways to effectively discover strange behavior trends with zero-day attacks. Since detecting the attack requires characterizing abnormal software behavior, AI monitoring is one of the only applications capable of efficiently doing so.

4. Staff Education and Awareness

As with many cybersecurity strategies, keeping staff at peak awareness is crucial. Educating team members – from IT to management – is another fundamental way to help mitigate damage caused by zero-day attacks and exploits.

Staff should have an in-depth understanding of Backup and Discovery  Recovery (BDR) policies should zero-day attacks occur. Additionally, they should have cursory knowledge over what a zero-day attack is and what it means. Set guidelines to help prevent potential intrusions and loss of information.

5. Reactive Updating

Once a zero-day attack is discovered, it’s paramount a resolution is reached. Whether this is accomplished by downloading the latest patch from a developer or by reaching an internal resolution, fixing the issue prevents further downtime.

It’s also important to set up preventative methods with the latest anti-malware software since they are your initial line of defense.


Zero-day exploits and attacks are nuanced modern threats capable of affecting any business, organization, and enterprise. Often, they are capable of attacking modern infrastructure. Anything handled by a network is vulnerable to attack. Some forms of zero-day exploit malware were developed by complex parties, such as the Stuxnet virus (dangerous enough to be categorized as a cyber weapon).

While it’s unlikely a small-to-medium sized business will ever counter something as complex as Stuxnet, it pays to be prepared. Exploits like ransomware are capable of causing irreparable harm to an organization’s infrastructure, resulting in extreme financial damage.

Prevention comes from awareness. To best keep your enterprise safe, always stay updated with news about the software and application platforms used by the organization. Hardware which also relies on apps or updates should be checked routinely as well. Additionally, keep in touch with the latest news about potential malware attacks developed as a zero-day exploit. Sometimes, knowledge is the best form of defense you have.

If you’d like to learn more about zero-day attacks or other cybersecurity strategies, you can read more at CyberDefenses.

About the author

CyberDefenses Inc.

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