What is a Zero-Day (0-Day)?: How to Prepare for Invisible Threats in Cyberspace

In the world of cybersecurity, zero-day vulnerabilities, zero-day attacks, and zero-day exploits keep many CISOs up at night. These terms, often shrouded in mystery and intrigue, denote a significant risk to digital systems and the sensitive data they hold. Understanding the intricacies of zero-day vulnerabilities and the exploits that leverage them is crucial for individuals, organizations, and governments seeking to fortify their defenses against cyber threats.

Zero-day terms defined

The term “zero-day” signifies that from the moment the vulnerability is discovered, there are zero days of protection, making it ripe for exploitation. Hackers can exploit these vulnerabilities to compromise systems, steal data, launch attacks, or disrupt operations.

1. What is a Zero-Day vulnerability?

Zero-Day vulnerabilities are a type of software security flaw or weakness that is unknown to the software vendor or the public. This means that the vulnerability is not yet patched or fixed, and no official security updates or measures have been released to address it.

2. What is a Zero-Day exploit?

Zero-Day exploits are cyberattacks that exploit a previously unknown vulnerability or software flaw in a computer application, operating system, or hardware device.

3. What is a Zero-Day attack?

Similarly, a zero-day attack is a cyberattack targeting an unknown software vulnerability. The attacker finds the vulnerability before anyone else, then quickly uses it for an attack.

How Does a Zero-Day Attack Work? 

The discovery of a zero-day vulnerability often follows a sequence of events. Initially, a researcher, a malicious actor, or even a user may find a flaw. However, instead of immediately reporting the issue to the vendor for a fix, the discoverer might choose to exploit it or sell the information on the black market. This underground market for zero-day vulnerabilities can be lucrative, as these vulnerabilities fetch high prices due to their potency and the potential for covert exploitation.

Once a zero-day vulnerability is discovered, it can be weaponized through an exploit. An exploit is a piece of code or technique that takes advantage of a vulnerability to gain unauthorized access to a system, escalate privileges, or execute malicious actions. Exploits can be deployed in various ways, including email attachments, malicious websites, or other vectors. They can target specific software or hardware versions, making it imperative for users to keep their systems up to date with patches and security updates.

What are Examples of a Zero-Day? 

Zero-day attacks have led to some of the most high-profile cybersecurity incidents in the last decade, including: 

1. Fortinet

In June 2023, Fortinet published an advisory about CVE-2023-27997, a critical vulnerability in FortiOS, the operating system for FortiGate firewalls and virtual private networks (VPNs).

Our team has provided guidance on how to identify vulnerable Fortinet devices within your organization and how to mitigate CVE-2023-27997.

2. MOVEit

The 2023 vulnerability affecting MOVEit file transfer software was widespread, affecting multiple organizations around the world in government, energy, transportation, retail, communications, and professional services. 

3. Log4j

The 2021 flaw related to Log4j enables threat actors to remotely execute commands via remote code execution (RCE) on nearly any machine using Log4j.

4. Chrome

In 2021, Google’s Chrome browser suffered a series of zero-day threats; the vulnerability was caused by a bug in the V8 JavaScript engine used in the Chrome web browser.   

5. Zoom

This 2020 zero-day attack saw hackers access a user’s PC remotely if they were running an older version of Windows, take over their device, and gain access to all their files.

Consequences of Zero-Day Exploits

One common type of exploit is the “drive-by download,” where a user unknowingly downloads malicious software by visiting a compromised website. The exploit code leverages the zero-day vulnerability to install malware on the user’s device, often without any visible signs of compromise. This stealthy approach allows attackers to infiltrate systems and establish a foothold for further malicious activities.

The consequences of zero-day vulnerabilities and exploits can be severe. They can lead to data breaches, financial losses, reputational damage, and even endanger national security. A successful zero-day exploit can give unauthorized access to sensitive information, such as personal identities, financial records, or intellectual property. Furthermore, exploited systems can be used as launchpads for further attacks, amplifying the potential damage.

How to Respond to a Zero-Day

Cyberattacks on critical infrastructure have slowly been increasing in severity over the last year; and the cost has gone up by $1.17 million to $5.4 million per incident, largely due to the growing number of third- and fourth-party vendors. Additionally, the number of nation-state attacks on critical infrastructure has recently doubled. Meanwhile, high severity vulnerabilities detected across publicly exposed digital footprints have increased 38%. With an average time of 14 days for an exploit to be released into the wild following the detection of a vulnerability, precise prevention and response strategies are essential.

Having a solid team when responding to a zero-day is key. Once a zero-day vulnerability is found, the clock is already ticking, so you need to have the right people ready to detect, triage, and analyze what you’re dealing with.That’s why training your employees is critical, and so is knowing how to reach your vendors if the usual means of communication are down.

Government’s Role in Stopping Zero-Days

Governments and international organizations also play a vital role in addressing zero-day vulnerabilities. They can establish regulations and frameworks that encourage responsible vulnerability disclosure and enforce penalties for those who exploit vulnerabilities for malicious purposes. Collaboration and information sharing between industry stakeholders, researchers, and government agencies are essential for a coordinated and effective response to the zero-day threat.

How to Avoid a Zero-Day Attack

Being able to mitigate the risks associated with zero-day vulnerabilities and exploits requires a multi-faceted approach. Vendors play a crucial role by implementing robust secure coding practices, conducting regular security audits, and fostering a culture of responsible vulnerability disclosure. Encouraging researchers and ethical hackers to report vulnerabilities to vendors, instead of exploiting them or selling them on the black market, promotes a safer digital environment.

In addition to vendor efforts, end-users and organizations must prioritize cybersecurity hygiene. This includes keeping software up to date, employing security measures such as firewalls and antivirus software, and educating users about phishing and other common attack vectors. Regular training and awareness programs can significantly reduce the likelihood of falling victim to exploits.

Furthermore, fostering a cybersecurity community that actively engages in proactive defense measures, such as vulnerability research and threat intelligence sharing, can aid in the early detection and mitigation of zero-day vulnerabilities. Security researchers and organizations need platforms to collaborate, share insights, and collectively work towards enhancing the overall security posture of not just their own environments but that of their third- and fourth-party vendors as well.

Looking for more Zero-Day content? Check out:  https://securityscorecard.com/zdaas/