What Are Zero-Day Attacks, and Why Do They Work?

Zero-day attacks have become a significant concern in the realm of cybersecurity, posing a formidable challenge to individuals and organizations alike. These attacks exploit vulnerabilities that are unknown to the software vendor, leaving systems exposed to potential breaches. As cyberthreats evolve, understanding zero-day attacks and implementing effective protection strategies is crucial for maintaining security.

Understanding Zero-Day Attacks

What is a zero-day vulnerability, exploit, and attack?

A zero-day vulnerability refers to a software security flaw that is unknown to the vendor. When attackers exploit this vulnerability, it becomes a zero-day exploit. A zero-day attack occurs when malicious actors use this exploit to compromise a system before a patch is available.

Why "zero-day"?

The term “zero-day” signifies that the vendor has zero days to address the vulnerability before it is exploited. This urgency highlights the critical nature of these threats because they can be leveraged by attackers immediately upon discovery.

Common targets of zero-day attacks

Zero-day attacks often target operating systems, web browsers, enterprise software, and Internet of Things (IoT) devices. These platforms are integral to daily operations, making them attractive targets for attackers seeking to maximize impact.

Why zero-day attacks are so effective

Zero-day attacks have several advantages in the cybersecurity landscape. Due to their novel nature, they can be challenging to detect and understand. Here are some common reasons they work when deployed against unsuspecting targets:

• No available patch: These exploits are unknown to both vendors and defenders, meaning they have not been identified and patched yet, leaving the door open for attackers.
• High-value targets: These attacks are often used in cyber espionage, ransomware campaigns, and advanced persistent threats (APTs) to target high-value assets with sensitive data.
• Difficult to detect: These exploits often are missed by traditional detection tools, especially those relying on signature-based detection, allowing adversaries to operate undetected.
• Speed and stealth: Successful breaches are more likely with zero-day attacks because attackers act quickly and quietly, allowing them to exploit vulnerabilities before they are identified and patched.
• Precision targeting: The target of these exploits is often a specific individual or organization. Spear-phishing and zero-click attacks are common tactics used to initiate the breach.

Real-World Zero-Day Attack Examples

No organization is immune to being targeted by a zero-day attack. In the real world, many key services, organizations, and platforms can be targeted by zero-day exploits:

• Nation-state sabotage: State-sponsored attackers can target critical infrastructure and utilities with zero-day exploits, rendering key services and life-saving utilities unavailable.
• Mobile surveillance: In telecommunications, carriers have witnessed zero-click exploits being used in mobile surveillance. This leads to compromised devices without any user interaction.
• Supply chain attacks: Global supply chains are appealing targets because they have a wide impact. In exploiting zero-day vulnerabilities, attackers can impact several groups in one attack, such as consumers, manufacturers, employees, and more.
• Frequently targeted platforms: Web browsers and email servers are common targets of zero-day attacks. These are widely used, increasing the potential for significant disruption.

How Zero-Day Vulnerabilities Are Discovered and Used

There are multiple groups and methodologies that work to discover, use, and inform organizations of zero-day vulnerabilities. These include:

• White-hat researchers: Often ethical hackers, also known as white-hat researchers, discover zero-day vulnerabilities via bug bounty programs and responsible disclosure. This helps vendors identify and address these issues.
• Black-hat hackers: On the flip side, if a black-hat hacker identifies a vulnerability before it is patched, the hacker can leverage it for gain, often selling exploits on the dark web.
• Government agencies: Some government agencies engage in offensive cyber operations, stockpiling exploits for strategic purposes. They also can inform organizations and vendors of these exploits, much like white-hat researchers.
• Thorough investigation: Internal security teams can leverage investigation capabilities, such as packet-level insights, to discover and understand zero-day threats, preventing future occurrences.

How to Defend Against Zero-Day Attacks

There are several measures security and network teams can take to more effectively avoid zero-day attacks. Some examples include:

• Leverage threat investigation: Detection alone often misses the unknown. Thorough investigation, leveraging deep packet inspection (DPI) at scale and forensic analysis, is key to identifying and preventing zero-day attacks from being successful now and in the future.
• Patch quickly: Prioritizing updates and effective vulnerability management is essential to mitigating the risk of zero-day attacks.
• Use behavior-based detection: Employing solutions such as endpoint detection and response (EDR), network detection and response (NDR), and extended detection and response (XDR) in combination with a strong investigation focus can help identify anomalous behavior that can signify zero-day exploits are being leveraged.
• Adopt zero-trust principles: Implementing a zero-trust security architecture, limiting user access, and continuously verifying identities can reduce the risk of unauthorized access to sensitive data.
• Segment the network: Strategic network segmentation helps contain breaches and minimizes lateral movement within a compromised system.
• Stay informed: Subscribing to security advisories and threat intelligence feeds helps keep organizations informed on emerging threats and vulnerabilities.

FAQs About Zero-Day Attacks

What makes zero-day attacks different from other cyberthreats?

Zero-day attacks exploit unknown vulnerabilities, making them particularly challenging to defend against compared with threats targeting known vulnerabilities.

Can antivirus software detect zero-day exploits?

Traditional antivirus software may struggle to detect zero-day exploits due to its reliance on signature-based detection methods.

Are zero-day vulnerabilities illegal to sell or use?

Although selling or using zero-day vulnerabilities for malicious purposes is illegal, ethical disclosure through bug bounty programs is encouraged.

How long do zero-day exploits typically remain undetected?

The duration for which a zero-day exploit remains undetected varies, but it can range from days to months, depending on the complexity of the exploit and the vigilance of security teams.

Staying Ahead of Emerging Threats with Investigation

Zero-day attacks represent a significant threat in the cybersecurity landscape, exploiting unknown vulnerabilities to devastating effect. Understanding these attacks and implementing proactive defensive strategies is essential for staying ahead of emerging threats.

Detection alone is not enough. Detection-focused tools such as EDR, NDR, and XDR on their own miss the unknown, allowing zero-day attacks to have a better chance of success. Leveraging investigation, powered by packet data, empowers teams with the actionable data to detect, understand, and prevent future attacks. Packets do not lie, and the network is the only place adversaries cannot hide.

Learn more about Omnis Cyber Intelligence.