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The quote "Perfection does not exist" applies to technology. Even the best technologies invented by world top organizations will contain flaws causing security vulnerability.

While software security vulnerabilities are daily analyzed by corporation quality assurance team and security experts, hackers and criminal groups are also major players when it comes to security vulnerability discovery. Unfortunately, on many occasions, hackers are the one who first discovers the so-called zero-day vulnerabilities to take a lead conducting their attacks.

In this article, we will look into the details of a zero-day exploit, reported zero-day incidents, potential dangers caused by zero-day attacks, and proper security measures to protect systems.

Zero-Day Definitions

The term Zero-Day, or 0-day, comes from the circumstance when developers have 0 days to fix the vulnerability. Any security issues that are not fixed by official support can be categorized as a zero-day problem.

Zero-Day Vulnerability applies to vulnerabilities that are not fixed by official support. Zero-day vulnerabilities are often considered high risk due to potential ongoing attacks.

Zero-Day Attack is used to refer to any attacks conducted against zero-day vulnerability.

Why is Zero-Day Vulnerability Dangerous?

When an issue such as bugs or vulnerabilities is found in the OS or software, vendors will release security patches to fix the problems. Users will then apply these hotfix releases to properly prevent cyber attacks.

However, if a vulnerability was announced before a solution is in place, users are left unprotected from the time the vulnerability is discovered until a security patch is released.

There are two main reasons why zero-day vulnerabilities are dangerous.

  • Difficult to detect attacks.
  • Difficult to prevent attacks.

Without applying the proper security measures provided by the vendors, there are not many ways for users to prepare for corresponding attacks. In such circumstances, attacks will not only be unable to prevent but event worst unable to be acknowledged.

How does Zero-Day Exploit Work?

Although software vendors dedicate a lot of effort to secure their product, some vulnerabilities are released undetected by quality assurance radar and get exploited by hackers. There are two types of a zero-day exploit, individual exploit and community exploit.

Individual Exploit

Individual exploit refers to an exploit activity by a solo hacker or closed criminal group who discovered the security hole takes advantage of the circumstance without disclosing to the public. By hiding the discovery from the public there will be less chance for the software vendor to find out about the vulnerability. This way the risk of exploit discovery will lower and life of exploit will increase.

Community Exploit

Community exploit applies to situations when vulnerability information becomes acknowledged by multiple hacker groups or hacker's community forum. The hacker who initially discovered the vulnerability will benefit through this situation by either trading information for money or asking others to dig deeper for additional security holes.

What Harm Can Zero-Day Vulnerability Cause?

Because zero-day exploit can be applied to many types of threats, the damage caused to users and devices can vary case by case. What makes zero-day exploit dangerous among other cybersecurity attacks is the lack of an official method to defend or worst case discovers.

Increase in Attack Occurrence

Users who run the software with zero-day vulnerability tend to get attacked more often. This is because hackers focus their zero-day attacks on any target that uses the vulnerable program. For example, if a major zero-day vulnerability is discovered on WordPress application, users who host a WordPress website will have a higher chance of getting impacted.

Cumulative Security Risk

Even if a vulnerability is considered low risk, zero-day vulnerability gives hackers the chance to research and experiment which may lead to more danger. Some experienced hackers can take advantage of a low-risk security hole to trigger critical exploits by conducting different attack strategies and analyzing the response details.

Example of Zero-Day Exploit Attacks

There are many zero-day attacks conducted throughout the years. The following examples are cases that were categorized as zero-day incidents.

Stuxnet: Stuxnet is a computer worm threat discovered in the mid-2010 attacking nuclear facility in Iran. Attacks were conducted with detail care utilizing four zero-day vulnerabilities. One of the zero-day vulnerabilities existed on a Windows OS based industrial computer. Capable to infect USB drives and other removable storage devices to expand its territory.

Sony Zero-Day Attack: In 2015 Sony Pictures Entertainment was attacked by hackers through their software's zero-day vulnerability. The incident caused data breach related to the business, such as unreleased movies, executive employers' emails, and organization roadmaps.

Poison Ivy: A Windows OS based virus designed in assemble programming language. Since 2005 Poison Ivy attacked a number of campaigns against governments, human rights groups, nation facilities, and defense departments. In 2012, the virus exploited an Internet Explorer zero-day vulnerability to attack users who visited the government website. Java-based zero-day vulnerability was also exploited for expanding the infection.

How to Protect Yourself from Zero-Day Exploit Attacks

Zero-day attacks are, by definition, conducted against software or system vulnerabilities that are undiscovered and cannot be prevented by proper methods. However, there are protection measures that can be applied to prevent hackers from taking full advantage of the circumstance.

Install Antivirus Software

To minimize impacts from zero-day attacks a system that provides comprehensive security measures becomes essential. Some antivirus software comes with additional protection features that will help establish activity monitor and fundamental protections against threats.

Update OS, Application, and Antivirus Software

Because technology vendors treat their zero-day vulnerabilities very seriously, they are constantly working on creating a patch to resolve the issue. Keep your eyes open for new version updates and hotfix releases, especially for OS, browser, and high usage applications.

Remove Unused Programs

Unused programs are often neglected by users and can lead to negative impacts. The outdated software version will increase security risk, especially if associated with network protocols. Even worst if the auto startup feature is left enabled causing constant vulnerability exposure. Make sure to organize the programs that run on your device and remove any unnecessary applications.


Properly configured firewalls can provide critical defense from zero-day attacks. While OS built-in firewall will give basic protection, firewalls that come with antivirus software provides advanced features to set up fundamental security.