What Is a Zero Day Attack? Meaning, Working, and Prevention Best Practices
A zero day attack is a breach that exploits a security flaw that has not been discovered by the owner of a software.
A zero day attack is defined as a breach that exploits a security flaw that has not been discovered by the owner of a software. This article explains a zero-day attack in detail, how it works, and the best practices to prevent it.
Table of Contents
What Is a Zero Day Attack?
A zero day attack refers to a breach that exploits a security flaw that the owner of a software has not discovered. This flaw may be at the code level, configuration level, or hardware/firmware level.
The term ‘zero day’ was initially used in the entertainment industry. It referred to when bootleggers distributed pirated copies of a movie or a song right on the day of the official release. In the technology world, zero day has been appropriated to vulnerabilities discovered by software vendors only after an attack is launched. Once a zero day attack begins, it becomes a race between the exploiters and the vendors; the vendors try to fix the breach as soon as possible, and the exploiters try to glean sensitive information or wreck the system as much as possible.
According to the Mandiant threat intelligence report of 2021, 40% of all recorded zero day attacks occurred in 2021 alone. The COVID pandemic in 2020 pushed many businesses online. Most organizations have moved some parts or even their architecture to the cloud. Many capabilities, such as team collaboration and customer relationship management, are now consumed as software-as-a-service (SaaS) applications.
More devices than ever before exist at the consumer end now. Users can access an application from a computer, a mobile phone, or a smartwatch. The Internet of things (IoT) has penetrated almost all homes and industries. Mobile internet connections are speedy and more accessible than before, with hardware becoming faster and cheaper and new improvements coming in every day. All these advancements add up to the fact that an organization’s attack surface has become larger. More endpoints now present themselves for a cybercriminal to attack than there used to be even half a decade ago.
This is why zero day attacks are hazardous to an organization. Even with the most robust security controls in place, it is inevitable that a vulnerability slips through the cracks. This vulnerability may be in the organization’s system or one of the services used by the system. In the case of the latter, it becomes a matter of the service provider honoring the SLA.
Usage of ‘zero day’ term
- Zero day vulnerability: This is a flaw in the existing software that a vendor is unaware of. The attacker, however, knows that it exists. This vulnerability can be anything from unencrypted data transfer to weak password policies.
- Zero day exploit: Once the attacker knows about the vulnerability, they try various methods to exploit it. This is usually in the form of an exploit code, a piece of code that tries to leverage the vulnerability to gain access to the system.
- Zero day attack: Attackers try to introduce their exploit code into the software through various means, such as social engineering. Vendors become aware of unusual behavior within their systems when the zero-day attack is successful. This atypical behavior is usually the result of a denial of service attack, ransomware, malware, or other forms of damage the exploit code is designed for.
Types of zero day attacks
1. Targeted zero day attacks: Targeted zero day attacks exploit security flaws in specific systems that contain sensitive or lucrative data. The victims of these attacks can be big tech companies such as Google, government agencies, or competitors within an industry.
2. Non-targeted zero day attacks: These attacks are broad attacks that exploit a specific vulnerability across multiple devices running a particular software, hardware, or firmware. For example, if the attacker finds a flaw in a version of a browser, they try to exploit every device running this browser version.
Most zero day attacks are targeted at operating systems, open-source code, network devices, hardware, firmware, cloud-based services, and IoT devices. Zero day attacks usually target financial institutions and banks.
See More: What Is a Security Vulnerability? Definition, Types, and Best Practices for Prevention
How Does a Zero Day Attack Work?
To properly understand how a zero day attack works, you first need to have a clear idea about the three key players involved in such attacks.
- The attackers: Attackers scour through the available information about a particular piece of software or hardware to find security holes. They work to leverage the discovered holes to gain access to private information, demand ransom money, or bring the system down. Such actors keep combing through possible cracks until they find a vulnerability that they can use to their benefit.
- The vendors: Vendors are the proprietary owners of the hardware or software. They are in charge of maintaining and upgrading the technology. Many organizations use the vendors of products and services to carry out their business and solve problems. Vendors are bound by service level agreements (SLAs) to provide security, privacy, and high availability. Vendors are the ones who have the power to react to a zero day attack. However, in some cases, attackers can target specific vulnerabilities within a company’s systems that have no vendors involved.
- The end users: End users consume products and services provided by vendors. The end user can be an organization, employees, or everyday consumers. They are usually the first to feel the impact of a zero day attack. Vendors work with end users to ensure the damage doesn’t increase.
A zero day attack can last between a few days to some months. The lifecycle of a typical zero day attack is as follows:
Stage 1: A vulnerability is created
The vendor introduces a bug in the system, which may be in the form of a piece of code added by a programmer. One example is a developer using an outdated version of a programming library to achieve a business feature.
The bug may be in the interface that allows the software to interact with other applications (such as an application programming interface (API). It can be the result of a misconfigured application or network device. It may also be due to outdated operating systems and hardware usage. Even basic security features, such as password policies, can become vulnerabilities that attackers can exploit.
At this stage, the vendor does not know that they’ve unwittingly introduced a vulnerability. This is either because they don’t have the security controls in place or testing has been inadequate, and business continues as usual.
Stage 2: Attackers discover the vulnerability
Attackers are constantly on the prowl for minor gaps that they can exploit in a system. This is particularly true for targeted zero day attacks, where attackers can run a reconnaissance operation to see what systems the targets run and how the infrastructure is built.
They go through a growing list of potential vulnerabilities. One example is an IoT device that has yet to be patched with the latest security upgrades. Another is the improper use of encryption for data storage and transfer. Attackers also resort to social engineering tactics such as phishing to see if they can find an unsuspecting human.
Stage 3: Vulnerability is exploited
Once the attacker finds a vulnerability, they figure out how to exploit it. Usually, they create specific code injected into the vendor’s systems using malware. They may intercept non-secure data packets to add malicious instructions during transit.
Some attackers simply package the exploit code and sell these as exploit kits on the dark web. These kits are purchased and used to carry out zero day attacks such as ransomware, denial of service, or cryptojacking.
Stage 4: Zero day attack begins
This is where the exploit code is executed within the vendor’s software. End users can now see odd behavior and, sometimes, may not even be able to access the application. Network monitoring systems may alert for unusual traffic. The symptoms of such an attack may be anything based on the type of vulnerability. This extensive nature of a zero day attack makes it very difficult for vendors to have a single mechanism in place for detecting them.
Stage 5: Vendor addresses the attack
The vendor is now aware that there is a vulnerability lurking somewhere in the system. The more complex their architecture is, the more difficult it becomes to point to the exact cause of the problem. If the zero day attack has caused an outage, backups are brought up while the issue is investigated. Vendors must inform their users of the exact nature of the attack and how it would affect them.
This is the window during which attackers try to create as much damage as possible. As such, it becomes imperative that the vendor responds to the attack as soon as possible.
Stage 6: Vendor releases a fix
The vendor figures out what the vulnerability is and comes up with a fix to prevent further exploitation. This fix is released in the form of a security patch. If it is a configuration issue, changes are made internally, and users are informed of the same.
Stage 7: End users deploy the fix
The vendor releases a fix to navigate the attack. End users now need to protect themselves by updating their systems with these security patches. Most organizations have a patch management system in place to deal with this. If it is a device-level fix, administrators ensure individual devices within the company network are upgraded as required.
At the end of this stage, the zero day vulnerability is officially declared as sealed, and any activity to assess the damage is carried on separately.
See More: What Is Patch Management? Meaning, Process, and Best Practices
The Log4j zero day vulnerability
The most infamous zero day attack in recent times was the Log4j zero day attack during the holiday season in December 2021. Apache Log4j is a popular open-source logging tool used by programmers with Java-based applications. It allows developers to create records of what the code goes through during execution for troubleshooting purposes.
Check Point Software Technologies, a cybersecurity firm, declared the Log4j zero day vulnerability as one of the most severe ever, targeting more than 40% of corporate networks across the globe. Big tech companies such as Microsoft, Apple, Google, IBM, Oracle, and Cisco were not immune to this vulnerability.
Even cybersecurity vendors such as Fortinet, SonicWall, and RSA Security were susceptible to the Log4j zero day vulnerability. MSN News reported that the list of potential victims included one-third of all web servers worldwide. Log4j was also found to be used in home network equipment such as routers and internet-connected smart devices.
Ecommerce company Alibaba’s cloud security team contacted Apache’s open-source team about a security flaw on November 24, 2021. The company also alerted them of a possible global cyber attack based on this flaw. In this case, the zero-day vulnerability was a flaw that allowed remote code execution (RCE).
Attackers could insert malicious text into the log messages that enabled code to be loaded from a remote server. They could also execute an exploit code within these logs to connect with the Java Naming and Directory Interface (JNDI). JNDI acts as an interface to further essential components within a system, such as Lightweight Directory Access Protocol (LDAP), Domain Name Service (DNS), and Java’s Remote Interface (RMI).
This single zero day vulnerability made end users open to a host of different attacks. The remote code execution could be used for data breaches, mining cryptocurrency, deploying malware, or even creating botnets that launch distributed denial of service attacks (DDoS).
On December 6, 2021, Apache released a patch addressing this vulnerability. On December 10, the U.S. government’s Cybersecurity and Infrastructure Security Agency (CISA) tweeted a notice of the known vulnerability, urging users to update their systems and use all means necessary to protect themselves. This patch, however, did not completely fix the flaw, and subsequently, three more vulnerabilities popped up. Apache released a patch for each of these on December 13, 17, and 28, respectively.
Attackers knew of the sheer volume of systems using Log4j in this zero day exploit case. Even as end users tried to protect themselves, attackers were busy hitting various systems through wide-ranging means, and some users could not patch themselves soon enough.
The effects of the Log4j zero day vulnerability linger, with many organizations still trying to patch all systems. CISA has issued a guide to assist organizations with remediations, and Apache has an ongoing list of outdated measures that users must refrain from utilizing.
See More: What Is Vulnerability Management? Definition, Lifecycle, Policy, and Best Practices
Zero Day Attack Prevention Best Practices
Zero day vulnerabilities can unleash unprecedented levels of chaos. Their unexpectedness and newness make zero-day attacks more debilitating than normal attacks. Here are some of the best practices that organizations can follow to minimize the impact of a zero day attack.
1. Perimeters need to be defined
Today’s organizations run on a potent mix of on-premise and cloud-based infrastructure. Multiple cloud-based services interact with the system. The first step toward preventing a zero-day attack is identifying all the endpoints and mapping a perimeter.
A well-defined perimeter allows security monitors to be more effective. It also enables DevSecOps teams to decide on the necessary security controls. For instance, one line of defense can be to use endpoint devices with built-in, hardware-enabled security.
Endpoint protection platforms (EPP) identify malware and malicious scripts, keeping them outside the network perimeter. Endpoint detection and threat response (EDR) solutions continuously monitor and record user behavior across various endpoints. They use data analytics and context intelligence to spot suspicious activity.
2. Position a well-equipped arsenal of security controls
Most zero day vulnerabilities open victims up to a series of attacks from different fronts. With this in mind, investing in a broad range of well-maintained security controls is wise.
Intrusion detection and prevention systems, firewalls, and content filtering software provide endpoint protection; however, they aren’t enough by themselves. Network monitoring software is required to alert the security team about abnormal traffic. Monitoring software usually works based on behavioral context. This is essential in a zero day scenario when the attack signature is unknown, which allows it to slip through endpoint security systems.
Other necessary security controls include patch management, password management, and identity and access management.
3. Segment the networks
Enterprise networks are complex webs with different types of networks woven together. Segmenting them and defining their requirements go a long way in protecting the entire network at large.
For instance, an internal network is accessed by employees and needs significant protection. A data center network connects all data center resources, and security in this context focuses on encryption. A guest network requires only basic browser protection. Defining each segment also allows architects to decide on the appropriate security requirements.
Besides, segmenting networks ensures that the impact of an attack is contained within a particular segment and doesn’t cascade onto the organization’s entire network.
4. Consider zero trust security
Zero trust is a security ideology that assumes all users, devices, and applications must be authenticated and validated, even if they are inside the organization’s trusted network. The traditional security approach only protects the endpoints. It assumes that they are reliable once the user or data is inside the network.
Zero trust networks are continuously monitored, and time-outs are enforced. Here, all users and devices are given the least privilege required to function. Access control policies are strict, and authentication is multi-layered.
5. Streamline the security process
As mentioned earlier, multiple layers of security are required to prevent a zero day attack. Organizations need to ensure that security is streamlined across all these solutions.
Segmenting networks and defining separate network policies is one way to do this. Defining user roles and creating appropriate access policies is another. Similarly, hardware such as firewalls can be grouped with related policies described for each.
Besides this group-and-govern approach, it is prudent to enable only relevant functionalities at each level of security. Overdoing security can lead to usability issues. Automation must be introduced wherever possible, particularly with patch management and policy updates. Ensure that configuration and management are confined to one or two consoles.
6. Use an optimal mix of human threat hunters and AI
Threat intelligence is information about possible vulnerabilities and existing ones from multiple sources. These sources are public feeds from organizations such as CERT and shared information with industry alliances.
Artificial intelligence leverages this threat intelligence to predict possible attack signatures. Machine learning in security is particularly effective because of the high volume of threat data. However, it is essential to remember that zero day vulnerabilities have unknown indicators of compromise (IoC). Human intelligence is required for intuitive, creative, and strategic thinking.
Many organizations offer big bounties to the public, urging hackers to play with their systems and spot zero day vulnerabilities. This way, they can stay a step ahead of malicious attackers.
7. Have an incident response plan in place
While prevention is the goal, it is also vital that an incident response plan (IRP) is in place. One cannot predict the effects of a zero day attack, and the IRP needs to be up-to-date and thoroughly tested.
8. Filter down technology to only the most essential
Technology is available for every aspect of a business. Any feature can be fine-tuned using an application, a programming library, or a service. While it is tempting to use every single one, the more secure option is to use only the most essential applications, especially in live servers.
9. Train your employees
According to the 2022 Verizon data breach investigation report, 94% of all attacks with known origins were delivered by email. Humans are the weakest link in security. Even with the most sophisticated technology and security strategies, an organization is vulnerable to internal threats and social engineering attacks in many ways.
Employees need to be trained to spot and handle suspicious behavior in the network, applications, and services they use. They also need to be provided with a plan of action in case of a suspected compromise.
10. Backups are crucial
Recovery from a zero day attack depends on how soon the systems can be back up again. This is why a well-thought-out backup strategy is crucial. Backup plans include which assets to back up, frequency of backup, how soon it can be leveraged to get systems running again, and how often they are tested for accuracy and reliability.
See More: What Is a Phishing Email Attack? Definition, Identification, and Prevention Best Practices
Takeaway
Tackling zero day attacks requires a comprehensive approach to security. However, it is possible to throw in too many layers of protection, losing sight of usability and productivity. The most efficient security systems find the right balance between preemptive and reactive measures. A good mix of automation and human intelligence can thwart zero day attacks.
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