What is a zero-day exploit? How can you prevent a zero-day vulnerability from being exploited?

What is a Zero-Day Exploit?

A zero-day exploit – also written 0-day exploit – is an attack that takes advantage of a vulnerability in software or hardware before the developer or vendor becomes aware of it. A zero-day vulnerability can occur in operating systems, web applications, plugins, or any software component. The term “zero day” signifies that developers have had “zero days” to address the vulnerability since they were not aware that it existed.

Zero-day threats are of significant concern for organizations since patches or mitigation measures are not available at the time they are exposed. As a result, hackers can exploit zero-day vulnerabilities to gain unauthorized access, compromise systems, steal data, or launch other malicious activities.

How Do Zero-Day Exploits Impact Organizations?

Zero-day exploits enable attackers’ abilities to penetrate organizations that do not yet have defenses in place. As such, zero-day threats present significant risks to organizations and individuals and may have severe impact on their financial, regulatory, reputational and legal health.

• Spreading Malware: Attackers use zero-day exploits to deliver malware and establish persistence, enabling further compromise of systems, network infiltration, and the potential for launching large-scale attacks.
• Data Encryption: Data encryption is the primary damage inflicted in attacks where zero-day vulnerabilities are used as the initial attack vector.
• Loss of Sensitive Data: Threat actors exploit zero-day vulnerabilities to gain unauthorized access to systems and steal and potentially expose sensitive information such as personal data, intellectual property, or financial records.
• Financial Loss: Organizations suffer financial losses due to the costs associated with investigating and remediating the breach, legal consequences, reputational damage, potential loss of business and ransoms, if demanded and paid.
• Disruption of Operations: Zero-day exploits disrupt critical services, resulting in downtime, loss of productivity, and negative impact on customer satisfaction.

Which Products are Targets of Zero-Day Exploits?

Threat actors seek zero-day vulnerabilities to exploit in specific types of targets:

1. The most zero-day vulnerabilities are discovered in widely used technologies of market-leading vendors. Microsoft, Google and Apple are generally the leading targets of zero-day exploits, since these products offer the largest base of attack.
2. Desktop and mobile operating systems and browsers are the most popular targets for zero-day exploits due to the large number of targets and the access they provide to user credentials and organization networks and apps.
3. VPNs and firewalls are attractive products in which to seek vulnerabilities to exploit since a successful zero-day exploit can provide access to the entire network of the breached organization – apps, data and operational assets.
4. In recent years, IoT devices have become attractive targets for zero-day discovery since they are widely dispersed and less likely to be monitored than user devices and business networks.

Motives for Zero-Day Attacks

• Nation-State Actors: Zero-day exploits are highly valuable tactics for nation-state actors who use them for intelligence gathering, surveillance, or to gain a strategic advantage in cyber warfare.
• Cyber Espionage Groups: These groups may be employed to serve nation-state interests or by businesses to gain a competitive advantage.
• Cybercriminal Groups: Financially motivated attacks constitute a large proportion of zero-day exploits, as indicated by the fact that the most commonly delivered malware in these attacks is data encryption.

Strategies for Mitigating Zero-Day Exploits

Organizations seeking to protect their networks, data and business at large need to implement strong protections to guard against zero-day attacks. While all risk from zero-day exploits cannot be eliminated, organizations can adopt several strategies to prevent exploits of many zero-day vulnerabilities and reduce the impact of any that succeed:

1. Stay Informed

Staying up to date with the latest information on zero-day exploits is crucial since it allows prompt response and management of vulnerabilities. Reputable cybersecurity sources that should be followed include CISA Cybersecurity Alerts and Advisories, the Center for Internet Security, the Zero Day Initiative (ZDI), and the National Vulnerability Database (NVD).

2. Isolate Browsers

Browsers are among the products in which zero-day vulnerabilities are most often discovered and exploited. Browser isolation protects endpoints from zero-day exploits even though, by definition, they cannot be detected. Browser isolation executes all active web code in virtual browsers in containers in the cloud. Because only safe rendering data reaches the endpoint, browser vulnerabilities cannot be exploited to deliver malware. For this reason, CISA recommends that all organizations implement browser isolation.

3. Apply Patches and Updates Promptly

Promptly applying software patches and updates is crucial for mitigating risk from zero-day attacks. Developers and vendors often release patches once they become aware of vulnerabilities. Organizations should establish a robust patch management process to ensure timely deployment of patches across all systems and software components. However, while developers and vendors are diligent about issuing patches before publicizing newly identified zero-day vulnerabilities, evidence shows that organizations often neglect to apply them promptly, or even at all.

4. Network Segmentation

Implementing network segmentation helps contain the impact of a zero-day exploit. By dividing the network into smaller segments, organizations can limit lateral movement and isolate affected systems, reducing the attacker’s ability to move freely across the network.

5. Intrusion Detection and Prevention Systems (IDPS)

Deploying IDPS solutions can aid in detecting zero-day exploits and limiting the damage they do. These systems use behavioral analysis, anomaly detection, and signature-based detection to identify suspicious activities or traffic patterns that may be associated with zero-day attacks. By alerting security teams in real-time, organizations can respond and contain the threat.

6. Application Allowlisting and Blocklisting

Application allowlisting allows organizations to control which applications can run on their systems. By permitting only trusted and authorized applications, organizations can reduce the risk of executing malicious code associated with zero-day exploits. However, extensive blocklisting may reduce productivity, increase user frustration, and create tension between users and IT security teams.

7. User Education and Awareness

Educating users on safe computing practices, social engineering, and the risks of suspicious emails and malicious websites can help reduce the likelihood of successful zero-day attacks. This is important in BYOD environments, where regular security awareness training keeps users informed about emerging threats, including browser exploits.

8. Vulnerability Management

Implementing a robust vulnerability management program helps identify and address known vulnerabilities promptly. While it may not directly mitigate zero-day exploits, a proactive vulnerability management approach ensures that systems are up-to-date, reducing the attack surface and making it harder for attackers to find successful exploitation avenues.