Cybercrime and cyberattacks are getting more sophisticated and more elaborate as technology advances. Zero-day attacks are among the most hard-hitting infiltrations because most organizations and corporate entities aren’t even aware of the possible system vulnerabilities.

What are zero-day attacks? How can security professionals help improve zero-day attack security? What are the measures organizations and companies should take?

Our blog post will aim to answer all these questions.

Zero-Day Attacks in the Digital Realm

Having proper cybersecurity protocols has become a priority not just for large companies but for organizations, elementary schools, and even grocery stores. As technology advances, attackers are also getting better at exploiting certain system vulnerabilities and weak security points. Lately, though, there are new threats that these entities have to face, and they are called zero-day attacks. As the name suggests, these attacks are carried out without any warning, and they account for around 80% of successful system hacks carried out. In 2021 alone, organizations were hit by 65 zero-day attacks globally, which might not seem impressive, but a single attack can affect thousands of organizations.

More specifically, zero-day attacks refer to a type of system infiltration in which attackers leverages those system vulnerabilities that organizations and software vendors never knew existed. It’s like burglars entering a digital back door that nobody in the organization knew existed and, as such, couldn’t protect. Zero-day attacks are classified as severe security attacks because neither the software developers nor the IT staff is aware of the system’s weakness.

Most of the time, attack vectors are browsers and mail attachments which can exploit the vulnerabilities within the system. Zero-day malware follows a similar concept. These pieces of software are computer viruses that antivirus programs simply can’t detect yet, infiltrating the system with ease. In most cases, zero-day exploits will target the symptoms of:

  • Various government departments
  • Large companies
  • Individual devices with access to valuable data
  • Home users using vulnerable systems to build massive botnets
  • Different types of firmware, IoT, and hardware devices
  • In specific cases, governments may also use zero-day attack protocols to infiltrate organizations, dangerous organizations, or countries that are threatening national security

Needless to say, because of the value of these zero-day vulnerabilities, several markets exist for them. On one hand, organizations hire researchers to help them discover system vulnerabilities and to create a strategy for mitigating them. On the other hand, there are also black and gray markets where hackers trade and/or sell these zero-day vulnerabilities, often for hundreds of thousands.

Zero-Day Attack Examples

As mentioned above, a single attack can have unspeakable consequences, causing massive damage to several affected organizations/corporations. To see the severity of these exploits, here are some of the most renowned zero-day attacks from the last few years:


The critical attack on the Apache Log4j happened in 2021. The infiltration had the potential to affect a myriad of applications before security vendors could create a patch that would resolve the issue. The popular logging tool in Java is a renowned favorite among developers, widely used in many apps and programs.

To infiltrate the system, hackers exploited the logging utility of Log4j, which allowed them to easily exploit the flaw via remote code execution. By exploiting this vulnerability, hackers could insert different pieces of text into the logging library’s messages. These texts could later load the code from remote servers. Hackers were quick to move, as they’ve targeted around 40% of all global corporate networks.


The site’s zero-day attack happened in 2021, and it affected around 700 million users, or roughly 90% of the entire user base of the platform. During the infiltration, attackers managed to exploit the API and scraped all the data they could grab. This resulted in publicly releasing data sets of around roughly half a billion users. Hackers were also threatening the company to sell the total data set of 700 million accounts.


During the summer of 2021, the Texas-based company released a major security update to mitigate the vulnerabilities in the Serv-U file transferring tech, which hackers managed to exploit. As later discovered by Microsoft, the attackers responsible for the attack were probably from China, based on their tactics, procedures, and victimology.

The attackers managed to connect to the Serv-U server’s open SSH port from where they sent malformed pre-auth connection requests. This allowed the hackers to inject malicious code into the system.

Internet Explorer’s Case

Microsoft’s legacy browser also suffered a zero-day attack in 2020 because of a major flaw in the browser’s scripting engine. More specifically, the way it manages objects in memory.

Hackers were able to enter the system by tricking browser users into visiting a specific website where they could exploit the system vulnerability. They pulled this off with the help of redirection links, phishing emails, and different server requests.


Sophos’ XG firewall also suffered a series of zero-day attacks in 2020, in which hackers tried to leverage the SQL injection flaw by trying to target the PostgreSQL server.

After exploitation, the vulnerability would let the hackers inject malicious code into the database, modifying the settings of the firewall and giving them the opportunity to install several pieces of malware.


As early as March 2020, the company warned its users about attacks that would exploit two different vulnerabilities that affected all supported versions of their operating system. Unfortunately, patches weren’t expected to be available for weeks. The zero-day infiltrations targeted RCE or remote code execution weak points in the ATM library (Adobe Type Manager), which was integrated into Windows with the task of managing PostCript Type 1 fonts.

The flaws in the library enabled the attackers to deploy malicious documents and run the system scripts remotely. The malicious docs arrived through various downloads or via spam. When the unaware users opened it, the scripts would infect their devices.

Zero-Day Attack Security Protocols

As already mentioned above, there are no existing antivirus signatures or patches for these exploits, making timely identification and mitigation hard. Even then, there are a couple of ways experts can detect previously unidentified weak points within a system.

Active Threat Hunting – Scanning for Vulnerabilities

By actively monitoring the system, security experts might be able to detect some of the zero-day weak points. Security vendors can launch automated protocols that simulate software code attacks, conduct code reviews, attempting to find vulnerabilities after launching a new product or following a software update.

While this proactive approach is efficient, it won’t detect every system vulnerability. And even those which get identified need a more thorough code review and an actual solution to mitigate the potential threat and to prevent the exploit.An efficient response to these detected weak points is crucial because attackers can be very swift to exploit these points of entry.

Patch Management

Another approach to improve zero-day attack security is by creating adequate software patches when new vulnerabilities are discovered. While this approach can’t prevent exploits altogether, it’s an efficient way of reducing the risks of attacks greatly.

The biggest drawback of patch management is time. Identifying weak points takes time. Developing the necessary patch and distributing it can also be a lengthy process. Needless to say, the longer the process, the higher the risks of potential exploitation.

Threat Validation and Sanitization

Proactive monitoring and patch management are effective; however, they don’t grant immediate security to a threat. Input validation doesn’t leave enterprise systems without protection while new code is being developed. Instead, it gives security staff a flexible way to respond and adapt to threats immediately. WAF or web application firewalls on network edges are a great way to scan incoming traffic, filter out malicious inputs, targeting vulnerabilities.

More advanced options, like RASP agents (runtime application self-protection), examine request payloads determining the nature of requests. When the agents detect a malicious request, they enable the system to defend itself. Some of these pieces of software are cloud-based, using a broad range of different crowdsourced security protocols for threat identification.

The Zero-day Initiative

This program rewards security experts who disclose discovered vulnerabilities instead of selling the info on different black markets. The ultimate aim of the program is to establish a broad research community that can alert software development companies before hackers expose the systems.

Other Ways to Combat the Unknown

Apart from the protocols we’ve listed above, there are other approaches organizations, and companies can apply to reduce the risks of zero-day attacks.

  • Make sure that the IT teams in your organization have their own patch management strategy in place. They don’t have to perform the updates manually; they can also leverage automated intrusion detection systems that can deploy virtual patches.
  • As mentioned above, use firewall technology. These security protocols monitor both incoming and outgoing requests, helping your IT team a great deal in identifying malicious activity.
  • Educate the rest of your team about the basics of cybersecurity and about the dangers of downloading shady software and opening spammy emails.
  • Because hackers commonly infiltrate an organization via poorly secured email systems, an organization should have a premium email security solution using AI-based tech to filter out malicious emails.
  • Make uninstalling obsolete software mandatory. Old software can easily be exploited by hackers. If possible, find new replacement programs with available patches.
  • The best approach to cybersecurity is multi-layered. Just like you have security staff in your offices with surveillance cameras and locks on the door, your cybersecurity approach can also benefit from firewalls, patching, active monitoring, along with other protocols.

As hackers are constantly looking for more sophisticated ways to infiltrate systems, ignoring the possibilities of zero-day attacks can cause massive damage to every organization. Apart from the precautions and the approaches mentioned above, corporate staff should also have an adequate response plan in place when attacks do happen. In these plans, every priority, procedure, and role should be well defined and easily accessible offline if needed.

Better Safe than Sorry

With the advancement of technology, hackers are becoming bolder, initiating all types of ransomware tracks. Zero-day attacks are also growing at a fast pace, urging both corporations, security experts, and developers to find ways to eliminate potential threats.

For now, the best way to protect an organization from zero-day attacks is by deploying a layered security approach where hackers need to cross several barriers to access the valuable information they’re looking for.