A zero-day exploit, also known as a zero-day threat, is an attack that targets a security vulnerability for which no patch or fix is available. The term "zero-day" refers to the lack of time the affected developer or organization has to address the flaw upon its discovery.
Understanding zero-day attacks
A zero-day vulnerability is a flaw in software, hardware, or firmware that is unknown to the party responsible for patching or fixing the flaw. Since these vulnerabilities are undiscovered, no patches or updates have been developed to address them. When attackers exploit these vulnerabilities, it results in a zero-day attack.
How zero-day attacks work
A zero-day attack begins when a vulnerability exists in a system, application, or device, often present from its release, but remains unknown to the vendor. The attack process typically follows this lifecycle:
- Discovery of the flaw: The vulnerability remains dormant until detected. Security researchers or developers might uncover it first, or hackers might find and exploit it. When discovered by hackers, the vulnerability is often kept secret and exploited before a patch is available.
- Public knowledge: Once discovered, the vulnerability may become publicly known. Vendors and security experts often notify users to mitigate risks by keeping software updated, using advanced security tools like firewalls and behavior-based detection, limiting attack surfaces, and monitoring for unusual activity, while hackers may share details among themselves. Some vendors might delay disclosure until a fix is ready, but this creates a risk of hackers discovering and exploiting it first.
- Development of exploits: Hackers work on creating a zero-day exploit to use the vulnerability for attacks. This process is fast, with workable exploits often developed within 14 days of a vulnerability’s disclosure.
- Cyberattack: Using the zero-day exploit, attackers infiltrate systems, steal data, or cause disruptions. Since no patch exists yet, defenses are limited.
- Response and patching: Once attacks begin, vendors typically respond quickly, developing and deploying patches within days to neutralize the vulnerability.
Examples of zero-day attacks
Stuxnet was a highly sophisticated computer worm discovered in 2010, specifically designed to target industrial control systems (ICS). It is widely believed to have been a state-sponsored cyberattack, aimed at sabotaging Iran’s nuclear enrichment program by exploiting multiple zero-day vulnerabilities in Windows systems and Siemens PLCs (programmable logic controllers).
EternalBlue is a cyber exploit developed by the NSA, which targeted a critical vulnerability in Microsoft's SMBv1 protocol (CVE-2017-0144). It was leaked by the hacker group Shadow Brokers in 2017 and became infamous for its role in the WannaCry and NotPetya ransomware attacks. EternalBlue allows attackers to remotely execute code on vulnerable systems, spreading malware like a worm across networks.
Challenges in defending against zero-day attacks
Defending against zero-day attacks is challenging because:
- Unknown vulnerabilities: The primary issue is that the vulnerabilities are unknown until they are exploited.
- Rapid exploitation: Once discovered by attackers, zero-day vulnerabilities can be rapidly exploited across multiple systems.
- Delayed detection: Detecting zero-day attacks can take time, during which significant damage may occur.
Strategies to mitigate zero-day attacks
Addressing zero-day vulnerabilities requires an approach integrating proactive defenses, strong cybersecurity protocols, and swift response plans. While it’s impossible to entirely eliminate the risk of zero-day exploits, implementing these strategies can reduce their impact and enhance resilience:
Regular updates: Regularly update all software and systems to minimize vulnerabilities.
Network segmentation: Isolate critical systems from general network traffic to limit the spread of attacks.
Advanced threat detection: Implement advanced security solutions like intrusion detection systems (IDS) and behavior analytics to identify and respond to suspicious activity.
Employee training: Educate employees on cybersecurity best practices to reduce the risk of social engineering attacks that can facilitate zero-day exploits.
Incident response planning: Develop and maintain a robust incident response plan to swiftly address and mitigate the impact of any attack.
Related: What is an IDS
What is an incident response plan?
FAQs
What is software?
Software refers to the programs and operating information used by a computer. This includes applications, operating systems, and utilities that perform specific tasks and functions.
What is hardware?
Hardware consists of the physical components of a computer system, such as the central processing unit (CPU), memory, storage devices, and peripheral devices like keyboards and monitors.
What is firmware?
Firmware is a type of software that is embedded into hardware devices. It provides low-level control for the device's specific hardware and can be thought of as the operating system for the device.
What is behavior-based detection?
Behavior-based detection involves monitoring the behavior of software, systems, and networks to identify unusual or suspicious activities that may indicate a security threat. This method analyzes patterns and behaviors rather than relying solely on known signatures, making it effective against new and unknown threats, including zero-day exploits.
What is a firewall?
A firewall is a network security device or software that monitors and controls incoming and outgoing network traffic based on predetermined security rules. Its primary purpose is to create a barrier between a trusted internal network and untrusted external networks, such as the internet, to protect against unauthorized access and cyber threats.
