Email Security Intelligence - What Is A Zero-Day Attack & How To Prevent Zero Day Exploit?

Zero-day attacks are becoming increasingly prevalent and problematic for businesses. The term “zero-day” is used to describe the threat of unknown or unaddressed security vulnerabilities in software or applications.  Thus, attacks that exploit zero-day vulnerabilities often occur without users’ knowledge, and can carry hefty costs for organizations in the form of lost productivity, data theft, system downtime, reputation damage and regulatory actions.

When it comes to mitigating your risk of suffering a zero-day attack, prevention is the best form of protection. Inadequately secured email systems are one of the most common ways that cyber criminals infiltrate organizations’ networks. Thus, it is incredibly important for businesses to ensure that their email system isn’t an open door to thieves! Implementing proactive, layered email security defenses is the most effective method of combating zero-day attacks and other dangerous, costly attacks.

Watch: Top Tips to Protect Against Zero-Day Attacks

What are Zero-Day Attacks and How do They Work?

A zero-day attack refers to a scenario in which threat actors exploit a vulnerability before developers have had the opportunity to release a fix for it -- hence the name of this threat. Zero-day attacks are especially dangerous because the only people who know about them are the attackers themselves. Once they have infiltrated a network, criminals can either attack immediately or sit and wait for the optimal time to do so.

There are various mechanisms by which threat actors launch attacks exploiting zero-day vulnerabilities. Typically, they involve targeting a system with malware once a criminal has found a way to exploit an unpatched vulnerability in a web browser or application. Malware usually arrives via email, and is downloaded when a user either clicks through a malicious link or downloads a malicious attachment.

Once downloaded, the attacker’s malware infiltrates a company’s files, stealing confidential data such as social security numbers, login information and passwords. Business plans and trade secrets are equally vulnerable. Any information that can either be used or sold is an attractive target in a zero-day attack. Zero-day malware accounted for over 50% of all malware blocked in Q3 2020, an increase of 14% year on year.

Who do Zero-Day Exploits Target?

While zero-day attacks frequently target high-profile businesses and governments, no organization is safe from this type of threat. In fact, research shows that SMBs, which may not have adequate cybersecurity solutions or teams in place due to investment limitations, may suffer more than larger organizations from the consequences of zero-day attacks. On average, SMBs endure double the damage costs associated with a successful endpoint attack compared to enterprises.

Zero-Day Vulnerabilities: A Valuable Asset for Cyber Criminals, Ethical Hackers and Government Agencies

Zero-day vulnerabilities and exploit codes are very valuable and are used not only by threat actors but also by nation-state spies and security researchers working for the NSA and the US Cyber Command. This has led to the emergence of a prominent market for buying and selling zero-day vulnerabilities and exploits, driven largely by the demand from government intelligence agencies. The zero-day market has three parts: the black underground market, the white market which encompasses bug bounty programs and security research and the “gray” market where researchers and companies sell information about zero-day vulnerabilities to militaries, intelligence agencies and law enforcement.

Famous Zero-Day Exploits

Some of the most notorious attacks that utilized zero-day exploits include:

  • Stuxnet: In this attack which targeted Iran's uranium enrichment plant at Natanz, a virus/worm reportedly developed by the United States and Israel exploited multiple zero-day vulnerabilities to spread and gain privileged access on systems. Stuxnet was unintentionally released in the wild when one of the engineers at an infected facility connected his work laptop to his home network. Over 15 Iranian facilities were attacked and infiltrated by the Stuxnet worm, which caused substantial damage to Iran’s nuclear program.
  • Aurora: In 2010, Chinese threat actors used a zero-day vulnerability in Microsoft’s Internet Explorer to hack into Google, Adobe and over a dozen other companies. The criminals were targeting Google’s source code in the hopes of discovering additional zero-day exploits.
  • RSA hack: In this infamous 2011 attack, cyber criminals exploited a zero-day vulnerability in Adobe’s Flash player to launch a spear-phishing campaign targeting RSA employees. The attackers stole information pertaining to the company’s SecurID two-factor authentication products. 

How Can I Patch Zero-Day Vulnerabilities on My iPhone?

Recently, Apple fixed an issue with the iOS and the newly launched iOS 17, as well as iPadOS, Safari, watchOS and macOS Ventura and Monterey. The attack was discovered by two security researchers who work for companies like “Citizen Lab” and Google's Threat Analysis Group, whose job is to protect users from state-sponsored hackers and commercial spyware dealers. 

Because hackers continue to find ways to steal data from individuals, Apple has stepped up and provided a “trio” of fixes. What are they?

  • The first vulnerability, CVE-2023-41993, involves Webkit, the browser engine for Safari. The researchers discovered the engine can be manipulated to execute rogue computer code if it processes certain web content. Hence, the vulnerability could be paired with a malicious message or website to trigger an iPhone to download malware potentially. 
  • The second vulnerability, CVE-2023-41992, can affect iOS’s kernel, the core part of the operating system. Exploiting this bug can help attackers elevate their privileges over the OS, enabling them to install programs or gain access to sensitive data. 
  • Meanwhile, the third vulnerability, CVE-2023-41991, can allow a malicious app to potentially “bypass signature validation,” enabling an attacker to circumvent the security check Apple uses to verify an iOS app is safe and legitimate. 

These are just a few of the vulnerabilities that Apple was able to install. The company has warned everyone there will be additional CVE entries coming soon. This is a sign that other exploits have been found. Users can protect themselves with these instructions.

  • To update an iPhone, go to Settings > General > Software Update. The device can also patch itself automatically if automatic updates are toggled on. Look for iOS 16.7 or iOS 17.0.1.
  • Mac users can go to the Apple icon  > System Settings. Then click General on the left side of the System Settings window and select Software Update on the right panel. The patch will arrive as macOS Ventura 13.6.

Best Practices for Preventing Zero-Day Attacks

Zero-day exploits are some of the most difficult digital attacks to prevent; however, implementing these tips and best practices will decrease the chances of your company falling victim to a zero-day attack:

  • Use an advanced, proactive email security solution: Traditional antivirus software is typically only effective in defending against known threats and, as a result, is often ineffective in protecting against zero-day exploits. When it comes to zero-day attack detection and prevention, every second matters! Only the most proactive, intuitive security solutions can prevent zero-day attacks using advanced AI and heuristics techniques to search for anomalous patterns not typically seen from a user or application. These advanced solutions are then able to develop fixes using AI (along with human intervention) and distribute them quickly and efficiently. Invest in a high-quality, comprehensive cloud email security security solution that is capable of protecting against zero-day attacks and has the capacity to rapidly distribute and implement fixes for zero-day vulnerabilities -- it will pay off!
  • Educate users: Many zero-day attacks capitalize on human error. Thus, user education is imperative in preventing these exploits. Teach employees and users good security habits, tips and best practices that will help keep them safe online and protect your organization from zero-day exploits and other digital threats.
  • Deploy a web application firewall: Deploying a web application firewall will help your company react to threats in real-time. A web application firewall continually scans incoming data for threats, providing organizations with the information necessary to suppress suspicious activity and stop an impending attack from occurring.
  • Implement network access control: Network access control is a tool that prevents unauthorized machines from accessing an organization’s network, decreasing the risk of hacks, exploits and breaches. It can also help to contain any damage to a particular network.
  • Use IPsec: IPsec encrypts and authenticates all network traffic, allowing a system to rapidly identify and isolate non-network traffic and suspicious activity. With this information, organizations stand a better chance of being able to recognize and stop attacks before damage is done.

How Guardian Digital can Help

Effective email security is critical in preventing zero-day attacks. Guardian Digital EnGarde Cloud Email Security provides comprehensive, end-to-end business email protection, effectively securing business email accounts against zero-day exploits, malware, phishing and other serious email threats. Key benefits of fortifying your business email with EnGarde include:

  • Multi-layered architecture, where individual layers of real-time security work harmoniously to provide complete, resilient protection against zero-day attacks and other advanced threats
  • Neutralizes threats associated with malicious attachments and links
  • End-to-end email encryption and secure delivery
  • Authenticates every email delivered using DMARC, DKIM and SPF
  • State-of-the-art heuristic technologies recognize malicious code and accurately identify and block zero-day viruses and highly targeted phishing attempts
  • Tighter security, flexible implementation and eliminated risk of vendor lock-in through the use of a transparent, collaborative development approach
  • Centrally managed cloud-based administration
  • Passionate, knowledgeable 24/7/365 customer support and around-the-clock system monitoring 

Want to learn more about zero-day attacks and how to mitigate your risk?

Do you have any remaining questions or concerns about zero-day attacks and how to protect your company from this growing threat? Please contact us. We would love to help!

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