What is Zero-Day Attacks?

Zero-day Exploits

Attackers use zero-day exploits to access confidential data belonging to organizations, disrupt critical infrastructure or engage in other forms of cybercrime. Attackers typically deliver these exploits via spear phishing attacks against organizational systems.

Time is needed for software vendors to identify vulnerabilities, create patches, and distribute them to users; during that period of time 0-1a zero-day attacks could occur.

Zero-Day attacks occur when hackers find and exploit new vulnerabilities before software vendors become aware. It could take days, months, or even years until these vulnerabilities are identified and addressed.

Protecting against Zero-Day threats requires keeping software and hardware updated with security patches, although this alone won’t stop all zero-day attacks.

Zero-Day Definitions

Zero-day threats refers to software vulnerabilities known only by attackers but not developers, or at least not until attackers discover them themselves. They typically occur between when vulnerabilities are first discovered (at time zero) and when vendors release patches or workarounds to address them (time one).

Criminal hackers use zero-day vulnerabilities to breach businesses, access valuable information, and disrupt operations. Security researchers and companies often notify software or hardware developers about these weaknesses to stop attacks from using them against vulnerable systems.

Organizations must create an effective defense against these stealthy threats that pose such serious danger, using preventative technology like next-gen antivirus and endpoint detection and response, in addition to creating a plan in case an attack does occur.

Zero-day attacks can take many forms, from spam email and phishing scams, to malicious websites, malvertising and spear phishing campaigns. Luckily, advanced analytic techniques like sandbox analysis can detect such threats before they reach the network, providing organizations with additional protection. When coupled with strategies like microsegmentation for reducing their attack surface area (Micro-segmentation) these tools may even help organizations reduce zero-day threats altogether.

Why are Zero-Day Exploits Dangerous?

Zero-day vulnerabilities give attackers an unfair advantage by enabling them to penetrate systems before being discovered, enabling them to steal information, disrupt operations or gain access to personal data – making these flaws one of the most dangerous cyberthreats ever conceived.

Once vulnerabilities are discovered, they can be exploited to gain control of an individual’s system or entire network and cause significant data or financial loss, unauthorized access to confidential information or even destruction of critical equipment.

As soon as a zero-day vulnerability is identified, software providers or security researchers typically announce it in order to alert hackers who use exploitable exploits against systems and networks before an official patch can be released, which may take weeks or months before implementation.

Even though most major vendors release security patches regularly, it is impossible to prevent all zero-day attacks. There are however steps individuals can take in order to help themselves protect against this type of vulnerability; by keeping software and operating systems up-to-date with latest patches will greatly lower their risk.

Zero-day vulnerability detection

Once a vulnerability is identified, cybersecurity researchers and software vendors work quickly to develop and deploy a security patch to address it. Meanwhile, hackers work tirelessly to exploit that same vulnerability before the patch becomes available – providing hackers an opening to penetrate networks, steal data or gain entry.

Zero day window of attack refers to the period between discovering a vulnerability and publishing its security patch, when hackers are likely to exploit it and sell it on dark web for large sums of money.

Vulnerability scanning can detect some zero-day attacks by looking for signs of suspicious activity; however, this method is far from foolproof. To protect against zero-day attacks effectively, implementing an ongoing patching strategy must include OS, applications, open-source components, hardware and even IoT devices; having a comprehensive vulnerability management program in place will strengthen resistance against attacks while speeding detection and remediation times and meeting compliance requirements more quickly.

1. Vulnerability scanning

Vulnerability scanning is an indispensable method for identifying and assessing modern security risks. It can identify hardware flaws, programming errors, packet construction anomalies, default configuration settings that leave vulnerable data exposed, potential paths leading to sensitive data sources and other exploitable weaknesses that attackers could exploit.

Vulnerability scans aim to detect threats before they enter your network and cause harm or disrupt business operations, and can assist with adhering to regulatory frameworks while strengthening your cybersecurity posture.

As opposed to signature matching, which only detects malware once victims have already fallen prey, pen tests detect zero-day vulnerabilities that attackers are exploiting to gain entry to your infrastructure. These vulnerabilities could include anything from an open door used by thieves for theft at an retail store to more complex bugs that allow hackers access data or run code remotely. Ideally, vulnerabilities found during production should be addressed during software development life cycle (SDLC), however sometimes they cannot always be rectified before an attack takes place – this is why vulnerability scanning tools play an integral part in identifying and mitigating vulnerabilities discovered post deployment – such as zero days.

2. Patch management

Patch management refers to the practice of applying software updates, also known as patches, to your IT infrastructure endpoints in order to keep them current with regard to software and operating systems – thus decreasing vulnerabilities that could be exploited by cyber threats.

Patch management processes typically include scanning an IT infrastructure to identify vulnerabilities and apply patches as quickly as possible to limit downtime. Implementation of such strategies takes careful planning and expertise.

Patches come in three main varieties, security fixes, bug fixes and feature updates. Security patches eliminate vulnerabilities on existing software that could expose it to cyber attacks while bug fixes help reduce bug counts in systems and improve overall software efficiency.

Attaining cyber attacks through systematic patch management, which involves the identification and deployment of software updates (patches) across an IT infrastructure, is one of the best ways to defend against them. Prioritization allows IT managers to prioritize patch deployment for high risk vulnerabilities while decreasing hacker exploit time by prioritizing patches that address critical flaws first.

3. Input validation and sanitization

Input validation and sanitization are critical security techniques to fend off zero-day attacks. These security methods compare incoming data against predefined rules such as length requirements, integer ranges and “is null” checks to detect anomalous content that could expose vulnerabilities in applications or services. Many languages and frameworks offer validation libraries which should be utilized alongside sanitization in order to make exploiting vulnerabilities harder for attackers.

Once a vulnerability has been identified, researchers and software vendors require time to research it, develop a patch, and distribute it to users. Meanwhile, criminals could use malware to gain entry to systems and steal or corrupt data in the interim.

Attackers typically gain entry by socially engineering victims into clicking links, opening files or visiting malicious websites. Hackers were recently able to breach Sony Pictures’ network using a zero-day vulnerability in Adobe Flash and Microsoft Windows, infiltrating assembly line machinery with malware before using file sharing websites to release sensitive data about its employees.

4. Zero-day initiative

Zero day exploits, or methods used by hackers to exploit vulnerabilities they previously were unaware existed, have proven invaluable in 2019. According to multiple databases and cybersecurity companies, record numbers have been utilized this year alone.

Security researchers often discover vulnerabilities in software programs and notify their vendors to address them; afterwards, the flaw is made public via CVE to help other organizations protect against it.

However, sometimes these discoveries leak onto the black market and end up sold to attackers. The Zero-Day Initiative is a new trend in the industry which seeks to avoid this scenario; unlike bug bounty programs it encourages researchers to search across all software industries for vulnerabilities that could pose threats.

However, this initiative cannot prevent all zero-day attacks from happening; therefore it is vital that organizations create an incident response plan with modern technologies, including prevention tech and timely patch management.

Recent Examples of Zero-Day Exploits

Attackers utilize zero-day exploits to gain unauthorized entry to systems, steal sensitive data and disrupt critical services. Unfortunately, these threats are difficult to detect because there are no signatures in antivirus software to identify them as threats.

As soon as a software vulnerability is identified, software programmers quickly work to develop and test patches, with distribution to vulnerable users taking place over time.

At this critical juncture, attackers can exploit vulnerabilities to harm programs, data, additional computers and networks. A great example is Stuxnet worm’s targeting of Windows and SCADA systems to disable them; another instance was Sony zero-day exploit allowing hackers to release confidential corporate information such as copies of movies awaiting release, business deals or top management email communications via file-sharing websites.


Zerologon is a vulnerability that impacts communication between user computers and domain controllers (servers), including sensitive information used to validate whether the computer belongs to valid users. Zerologon takes advantage of how encryption is implemented during this function to bypass authentication and impersonate valid users without detection by law enforcement authorities.

Tom Tervoort of Secura discovered a flaw in Microsoft’s Netlogon Remote Protocol that allowed him to exploit passwords for computer accounts differently from user accounts – this allowed attackers to brute force until their target account had been compromised.

This vulnerability received the highest CVSS score because it allows an attacker to gain access to domain controllers, which poses a tremendous threat for organizations as machine accounts play an essential role in authentication and authorization within your network.


Sophos is another cybersecurity vendor with an excellent track record in malware detection and prevention capabilities, offering both desktop and mobile apps which are sleek and user-friendly, along with an intuitive dashboard for easier control.

Sophos recently disclosed a zero-day vulnerability in its XG Firewall management interface that was exploited to collect firewall data and download an malicious backdoor known as Asnarok Trojan, according to Sophos.

Sophos swiftly responded with an emergency hotfix to close the security hole, notifying only a small number of its customers who may have been affected. Sophos has implemented a workaround which temporarily disables WAN access to its firewall management interface until this issue can be addressed properly; they have also added this flaw to their CVE catalog so customers should apply patches immediately.

Internet Explorer

An Internet Explorer zero-day vulnerability known as CVE-2020-0674 execCommand use after free vulnerability is currently being actively exploited in the wild. If successfully exploited, an attacker could execute code with full user privileges and even gain complete control of their system.

Google Threat Analysis Group researchers Benoit Sevens and Clement Lecigne discovered the flaw, associating it with North Korean hacker group APT37. Threat actors used documents referencing the Itaewon crowd crush to lure victims into downloading malware.

Microsoft released an out-of-band security patch, leaving unpatched Internet Explorer users vulnerable to attacks from attackers using MHT files that render Web-hosted content within Office documents.

Microsoft RCE

Microsoft released a patch this month for CVE-2023-21716, an RCE vulnerability affecting various versions of Office and 365 Applications. According to Microsoft, exploiting it requires convincing a victim to open or preview an RTF file with malicious content, then exploiting that file through RCE attacks.

An attack based on data tampering can result in ransomware being deployed onto compromised devices and allow an attacker to gain complete access. Implementation of input sanitization and validation, network segmentation, zero trust policies and access management platforms may help mitigate such attacks.

Microsoft analysis indicates that exploit code could be released; however, they have not seen instances of real-world attacks using this vulnerability. Given its significant ramifications and current use by an anonymous group allegedly linked with Russian intelligence services, organizations should prioritize updating as soon as possible.

How to Prevent Zero-Day Exploits?

Businesses can take numerous measures to protect themselves against zero-day attacks. One key measure is making sure their software and other platforms are regularly updated – even though this can seem tedious at times, those updates often include security patches to address software gaps that hackers could exploit.

Step two is using advanced detection methods. Many of these technologies rely on existing databases of malware to recognize patterns in the behavior of files entering your network and block them, however due to zero-day attacks being unique and unknown they may bypass traditional signature matching systems.

Businesses must also be capable of quickly discovering and implementing security patches when vulnerabilities are identified by researchers or software vendors, because the longer a vulnerability remains undetected, the greater its chance of leading to breaches. By accepting that no system can ever be 100% secure and having plans in place to minimize damages caused by breaches, businesses can move forward with confidence.

Sam is an experienced information security specialist who works with enterprises to mature and improve their enterprise security programs. Previously, he worked as a security news reporter.