What is a Zero-Day Attack?

Published On - March 14, 2024

Zero-day attacks target undisclosed vulnerabilities ("zero-day exploits"). These are software weaknesses unknown to vendors, giving them "zero days" to patch. Imagine a bug in your system's core code. Hackers craft malicious code ("exploit") to utilize this bug, gaining unauthorized access. Unlike known vulnerabilities with available patches, zero-days bypass traditional defenses. This grants attackers a significant window to steal data, deploy malware, or disrupt operations before a fix emerges. Therefore, constant security vigilance and rapid software updates are crucial to mitigate these high-risk attacks.

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Cyberattacks come in a range of different forms and exploit various types of vulnerability. Organizations are responsible for protecting themselves against these attacks, both to comply with regulations and to protect their employees, customers, and proprietary data. One of the most common and yet most difficult flaws to protect against is a zero-day attack. But what is a zero-day attack, and how can it be exploited?

Zero-Day Definition

The term Zero-Day is used to describe recently discovered security vulnerabilities that hackers can use to attack systems. Zero-day (also written as 0-day) refers to the fact that security teams were unaware of their software vulnerability, and they have “0” days to fix it. A zero-day attack happens when hackers exploit the weakness before developers have a chance to work on a security patch or apply an update to fix the issue.

The term Zero-Day is often associated with the terms Vulnerability, Exploit, and Threat and these terms are explained below:

  • A Zero-Day Vulnerability is an unknown security vulnerability or software flaw discovered by attackers before the developer has become aware of it. A threat actor can target this with malicious code.
  • A Zero-Day Exploit is the method a malicious actor uses to attack a system.
  • A Zero-Day Attack occurs when a hacker releases malware to exploit the software vulnerability, causing damage or stealing data before the software developer has patched the flaw.

Examples of Zero-Day Attacks

A zero-day attack can take place at any company at any time, and often happens without the company realizing. High-profile examples of zero-day attacks include:

2022 – Chrome Attacks

In 2022, hackers exploited a zero-day remote code execution vulnerability in Google Chrome web browsers. Phishing emails were used by hackers to direct victims to spoofed web sites, which used the Chrome vulnerability to install spyware and remote access malware on victims’ machines. This vulnerability was quickly patched but the hackers covered their tracks well, and researchers still don’t know exactly what data was stolen.

2020 – Zoom

A vulnerability was found in the Zoom video conferencing platform. Hackers would access a user’s PC remotely if they were running an older version of Windows and if the target was an administrator, the hacker could completely take over their machine and access all their files.

2020 – Apple iOS

Apple’s iOS is often seen to be the most secure of the major smartphone platforms. However, in 2020, there were at least two sets of iOS zero-day vulnerabilities, including a zero-day bug that allowed attackers to compromise iPhones remotely.

2019 – Microsoft Windows, Eastern Europe

This attack focused on local escalation privileges, a vulnerable part of Microsoft Windows, and targeted government institutions in Eastern Europe. The zero-day exploit utilized a local privilege vulnerability in Microsoft Windows to run random code, install applications and view and modify data on compromised applications. Once the attack was detected and reported to Microsoft, a patch was developed and rolled out.

2017 – Microsoft Word

This zero-day exploit affected personal bank accounts. The victims were people who unwittingly opened a malicious Word document. The document displayed a “load remote content” prompt, showing users a pop-up window that requested external access from another program. When victims clicked “yes,” the document installed malware on their device, which was able to capture banking log-in credentials.

2014 – Sony Pictures:

This is one of the most well-known zero-day attacks. It took down the Sony network and led to the release of its sensitive data on file-sharing sites. The attack happened in late 2014 and saw the leak of information around upcoming movies, the company’s business plans, and personal email addresses of senior executives.

How a Zero-Day Exploit Works

The timeline of zero-day exploitation happens over several stages from vulnerability introduction to security patch and takes place as described here:

Software is created which, unknown to the vendor, contains vulnerable code. This vulnerability is discovered by a hacker before the vendor realizes it exists or before they can fix or patch it. The hacker then writes and deploys an exploit code while the vulnerability is still open.

The vendor becomes aware of the vulnerability but is unable to fix it as no patch is available. At this stage, the vulnerability is publicly announced, which advises users and attackers of its existence.

If attackers have created zero-day malware targeting the vulnerability, then antivirus vendors can immediately identify its signature and they should then be able to provide protection against it. However, systems may still be exposed if there are other ways of exploiting the vulnerability.

Once the vendor releases a public fix to close the vulnerability, it can be deployed by users. The time frame for releasing the fix will depend on the complexity required and how much priority it is given. Releasing a security patch does not, of course, provide an instant fix as it relies on the users being aware that they need to deploy it and carrying out the deployment. To overcome this, organizations and individual users should employ automatic software updates and take notice of update notifications.

How to Prevent Against Zero-Day Attacks

To protect against a zero-day attack, it’s essential for organizations to follow cybersecurity best practices which include:

  • Keep all software and operating systems up to date. Developers work constantly to keep their software updated and patched to prevent the possibility of exploitation. When a vulnerability is discovered, developers will work quickly to issue a patch. But it does also depend on the users making sure that their software platforms are always up to date. The best strategy is to enable automatic updates, so your software is updated routinely, and without the need for manual intervention.
  • Use only essential applications. The more software you have, the more potential vulnerabilities you will face.
  • Use a firewall. A firewall can play an essential role in protecting your system against zero-day threats. You can ensure maximum protection by configuring it to allow only necessary transactions.
  • Educate users. Many zero-day attacks exploit human error. Teaching employees good safety and security behavior will help keep them safe online and protect organizations from zero-day exploits and other digital threats.
  • Use a comprehensive antivirus software solution.

How Lepide Helps

The Lepide Data Security Platform enables organizations to detect and respond to suspicious activities in a timely manner. Through the continuous monitoring of user activities, organizations can identify deviations from normal behavior and potential threats that could indicate an attack. The Lepide Solution uses machine learning algorithms and behavioral analytics to analyze user actions. This then enables the detection of changes to user behavior patterns and provides indicators of compromise. The platform’s real-time alerting capabilities ensure prompt notifications about suspicious activities, enabling security teams to take immediate action to mitigate the threat. In addition, the comprehensive reporting capabilities of the Lepide Solution can provide valuable insights into user activities. By employing user activity monitoring, alerting, and reporting, organizations can proactively protect against identity-based attacks.

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