5 essential System Design security practices for 2025

Imagine this: You build a fortress with walls tall enough to touch clouds ... but forget to lock the door.

That's what happened to Equifax in 2017, when a single unpatched vulnerability in Apache Struts exposed the personal data of 140+ million people.

The consequences were catastrophic: an estimated loss of $1.4 billion, plus a long string of lawsuits and regulatory penalties.

The kicker here is that the breach didn't happen because Equifax lacked a strong security system. It happened because of one tiny oversight.

Equifax's story is a stark reminder of the absolute importance of security in System Design. One missed update, one weak API, or one poorly planned component can make even the strongest systems come crashing down.

In today's newsletter, we'll cover:

• How cybersecurity threats are becoming more sophisticated

• The role of security controls in protecting your system

• 5 essential security measures to strengthen your System Design

• 8 key techniques for bolstering security

Let's go.

The evolution of cybersecurity threats#

Security threats have evolved considerably—becoming smarter, faster, and more adaptive. In the early days, cyber threats were simpler, like viruses spread through floppy disks or phishing emails that were easy to spot.

But as technology advanced, so did attackers' methods. Today, threats are highly sophisticated as bad agents use AI to predict weakness, social engineering to manipulate users, and complex malware to slip through the cracks. We now deal with ransomware, supply chain vulnerabilities, and advanced, persistent threats.

Here's a closer look at how threats have evolved over time:

Security is no longer just about keeping viruses out—it's a constant game of chess, where every move by attackers demands an equally smart countermove.

Importance of security-first System Design#

Security is a fundamental part of System Design, not a last-minute addition.

Instead of responding to threats, organizations must proactively design systems that anticipate them effectively. The cost of poor security architecture goes beyond financial loss—it can permanently damage a business’s reputation.

A good example of that is Yahoo's 2013 data breach, where attackers stole the personal information of all 3 billion user accounts. Yahoo's delayed response and lack of security controls led to an irrevocable loss of trust, reducing its sale value by $340 million.

Smart security starts with early risk assessments—evaluating every component for vulnerabilities. Skipping this step can lead to weaknesses that bring your system down. It's also important for:

• Proactive defense against cyber threats and vulnerabilities.

• Adhering to data privacy and compliance such as GDPRGeneral Data Protection Regulation (GDPR) is a European Union regulation that governs data privacy and protection of individuals within the EU and the European Economic Area (EEA)., HIPAAHealth Insurance Portability and Accountability Act (HIPAA) is a US law that regulates the handling of sensitive health information (PHI) to protect patient privacy., CCPACalifornia Consumer Privacy Act (CCPA) is a U.S. law granting California residents rights regarding collecting, using, and selling personal data., etc.

• Preventing financial loss or cost efficiency.

• Securing the company’s reputation and future.

Next, we’ll explore the security controls that make this proactive approach a reality.

The importance of security controls#

Understanding the importance of security is one thing. Turning that awareness into action is another.

This is where security controls come in—they’re the concrete measures that bridge the gap between security concepts and real-world protection. Security controls enforce policies and mitigate risks, forming the backbone of a secure system.

The 3 categories of security controls include:

1. Preventive controls: These are designed to stop threats before they occur. They serve as the first line of defense, aiming to prevent unauthorized access and mitigate vulnerabilities, including techniques like authentication, authorization, encryption, firewalls, and antivirus or antimalware.

2. Detective controls: They identify and alert the administrator or cyber security team of potential issues, such as intrusion detection, allowing for swift action. These include logging, auditing, monitoring, alerting, and intrusion detection systems. 

3. Corrective controls: They aim to mitigate damage after a security incident. These controls focus on recovery and ensuring the system can return to a secure state, including backup and recovery, quarantine isolation, and patch management.

These security controls should be applied at various system levels, such as the network, host, application, data, and user.

5 essential security measures in System Design#

Now we're ready to dive into the core components that will help safeguard your systems.

Building a secure system requires integrating components that strengthen security at every layer. Here’s a look at the 5 key elements of System Design and their roles in protection:

1. API gateway#

The first component to integrate into the system is the API gateway. An API gateway enhances security by acting as a single entry point for all API requests, allowing for centralized authentication, authorization, and traffic control management.

It can perform request validation and response transformation to filter out malicious input, and it often integrates with security tools like firewalls and threat detection systems, thereby reducing the overall risk of security breaches in the form of malicious requests to the backend services.

2. Load balancer#

Next, we can use a load balancer to secure our system. A load balancer enhances security by distributing incoming traffic across multiple servers, reducing the risk of downtime from DDoS attacks and preventing any single server from being targeted.

Moreover, it includes features like web application firewalls to filter malicious traffic, encryption to protect sensitive data, monitoring the health of backend servers to redirect traffic from compromised servers, and restricting access through IP allowlisting and blocklisting.

3. Rate limiter#

Load balancers alone cannot mitigate distributed denial of service (DDoS) attacks and borrow help from rate limiters to enhance security by controlling the number of requests a user or system can make to a service within a specific time.

This helps prevent abuse and protect against DDoS attacks by ensuring no single user or bot can overwhelm the system with excessive requests. Moreover, we can identify and block malicious activity with rate limiters by monitoring unusual request patterns to secure our system.

Circuit breakers enhance system resilience by isolating errors or malfunctioning components to prevent cascading failures.

4. Microservices#

Microservices enhance security by promoting a decentralized architecture where each service operates independently, allowing for more granular control over security policies and access management. This isolation means that vulnerabilities in one service are less likely to affect the entire system.

Additionally, we can implement security measures tailored to the unique functionalities of each service, for example, using different authentication methods or access controls. Overall, we enhance the system’s security structure to align with scalability.

5. Data partitioning and sharding#

Data partitioning and sharding enhance security by distributing data across multiple locations or databases, reducing the risk of a single point of failure or breach.

This approach limits exposure, as attackers must compromise multiple partitions or shards to access all data. Furthermore, it allows for tailored security measures for each shard, such as applying different encryption methods or access control based on data sensitivity.

The main goal of partitioning in System Design is to enhance availability, performance, and scalability rather than security. However, as with other components discussed above, improved security is often a beneficial side effect.

Techniques for enhancing system security#

In addition to discussing the 5 key components of a secure System Design, let's also cover 8 powerful techniques you can use to enhance security.

These techniques provide actionable strategies to protect systems against threats and vulnerabilities, discussed in the subsequent section.

1. Authentication#

Authentication is like the key that unlocks the door to our digital world. It’s the first step in ensuring that the person trying to access our system is who they say they are.

Think of verifying a friend at your front door before letting them in. In the online realm, this usually involves something familiar, like a username and password. But relying only on these methods can be risky, as passwords can be stolen or guessed.

That’s where multi-factor authentication (MFA) comes in, adding an extra layer of security.

MFA requires users to provide something they know (like a password) along with something they have (like a smartphone app or a text message code) and/or something they are (e.g., a retinal scan, a fingerprint, etc.). This combination makes it much harder for unauthorized users to gain access.

By prioritizing a strong authentication mechanism, we create a more secure environment.

2. Authorization#

Once we’ve been authenticated (proving who we are), authorization determines what we can do within the system. It’s about setting the rules and ensuring users can only access the resources necessary for their roles. For instance, a regular employee might access certain files and applications, while a manager may have broader access, including sensitive financial data.

This role-based access control (RBAC) ensures that users don’t wander into areas they shouldn’t, which helps prevent data breaches and maintain confidentiality. Organizations can safeguard their sensitive information by clearly defining and enforcing authorization policies.

For example, suppose you want to sign up with Educative using Google. In that case, the system will verify the user’s identity and ensure they are who they claim to be (authenticate), and also provide the necessary authorization by granting the Educative limited access to specific users information through an access token, as shown below:

Best practices for authentication and authorization#

Now that we’ve explored authentication and authorization, let’s discuss the best practices that help achieve them securely and efficiently.

3. Data security#

Data security is another vital layer to consider. Just as authentication verifies user identities and authorization restricts access, encryption protects the data, ensuring that it’s unreadable without the proper keys, even if it’s intercepted.

Encryption is vital for securing data both in transit and at rest:

• Data in transit encryption protects data as it moves between users and servers across different networks, preventing interception. Transport layer security (TLS) is commonly used here, encrypting data on the network level so that only the intended recipients can decode it.

• Data at rest encryption secures stored data, protecting it from unauthorized access if devices or servers are compromised. The advanced encryption standard (AES) is widely used for this purpose, providing strong symmetric encryption that encodes data using a single, unique key.

Another technique to protect sensitive data is data masking and tokenization, which involves replacing actual data values with altered or tokenized values while maintaining the original data structure and usability within databases.

• Data masking replaces sensitive data with realistic, fictional data that maintains the same format, which is valuable for non-production environments like testing or development. This allows teams to work with data that appears real but does not expose actual data, reducing data exposure risks.

• Tokenization, on the other hand, substitutes sensitive information with random tokens. These tokens have no exploitable value outside the secure tokenization system that links them to the original data. Tokenization is commonly used in finance to handle credit card information. It helps prevent unauthorized access to sensitive data without changing the structure of the database.

4. Network security#

After securing the doors with authentication, locking down permissions with authorization, and wrapping sensitive data in encryption, it’s time to turn our attention to our network.

Imagine it as a bustling city of data where only the right amount of traffic should be allowed in, and every path needs close monitoring. This is where network security becomes the default choice to safeguard our digital city from intruders, utilizing techniques such as:

• Network isolation and segmentation: Imagine a massive office building with multiple floors, where each floor is dedicated to a different department. Virtual local area networks (VLANs)VLAN (virtual local area network) is a configuration that segments a single physical network into multiple logical networks. This allows devices on different VLANs to communicate as if they are on separate networks, improving security and performance. act like floor layers that separate these departments, creating secure, controlled spaces within a single network. Only people with the right permissions can access each floor, like role- or attribute-based access. Firewalls are like security guards stationed at each entry point, checking badges and enforcing the rules. Even if someone sneaks past the main door, firewalls ensure they don’t have access to every department.

• Zero trust access control: With zero trust, we never assume anyone’s credentials make them trustworthy. It’s like a security checkpoint at every door, verifying each entry with the never trust, always verify rule. Access is granted based on real-time context, ensuring that only the right people access the right areas.

• AI-driven network monitoring: With the advancements in AI, AI-driven monitoring has become crucial to continuously detect anomalies and respond with AI/ML tools. It is like having a smart security system that learns from every event, detecting even the smallest unusual behavior and flagging it in real time. It serves as the network’s eyes and ears, constantly monitoring and analyzing every activity for potential threats and responding swiftly.

• Adaptive network security: Think of adaptive security as a highly responsive security system constantly on alert and adjusting as new threats appear. This system learns from every attempted break-in, fine-tuning defenses in real time to adapt to an ever-changing landscape of risks. It’s like having a security system that’s always one step ahead.

5. Incident response and disaster recovery#

Understanding that even the best code can face unexpected challenges is crucial. This is where the incident response and disaster recovery come into play, serving as your safety net when things go wrong.

• Incident response: Think of incident response as our emergency drill, preparing for the worst to minimize damage when a breach occurs. A solid incident response plan outlines the steps to quickly identify, contain, and remediate an incident, helping protect our data and reputation.

• Disaster recovery: A well-defined disaster recovery plan ensures we can quickly bounce back from an unexpected event, such as a cyberattack, natural disaster, or system failure. Key elements like regular data backups, secondary data centers, and cloud storage options ensure that vital information is always within reach. Disaster recovery is the foundation that ensures that our business can keep moving forward, no matter what comes our way.

6. Secure third-party integrations#

Securing third-party integration is very important, as third-party applications of other services, partners, and vendors can be an open door to our system and cause irreversible damage if not properly managed.

Third-party risk management is crucial for secure System Design. Cybersecurity experts should carefully analyze the security approaches implemented by service providers and take proper steps to reduce the risks of compromising the system by having a zero-trust policy.

7. Real-time monitoring and alerting#

After securing third-party integration and adopting a secure software development life cycle with robust coding practices, it’s equally critical to maintain system security through continuous monitoring and alerting.

Monitoring lets teams stay aware of all system activities and watch for unusual patterns indicating potential threats or vulnerabilities.

Paired with effective alerting, monitoring enables real-time responses to issues, quickly addresses security incidents, and minimizes attackers’ time to exploit weaknesses.

Implementing a Security Information and Event Management (SIEM) system is a powerful step toward robust security monitoring and incident response. SIEM systems collect and analyze data from across an organization’s networks, servers, and applications in real time, looking for suspicious activities and potential security threats.

8. Future-proofing security#

Future-proofing isn’t just about addressing today’s needs, but preparing tomorrow's challenges.

As technology evolves, taking the initiative and future-proofing our security measures becomes essential to stay ahead of new threats. The digital world is currently changing, and proactive planning for future challenges ensures resilience against threats that don’t yet exist but may soon surface.

Let’s explore a few key areas in future-proofing security:

• Quantum-resistant security: With the advent of quantum computing, today’s encryption methods may soon become vulnerable. Preparing for this shift means incorporating quantum-resistant cryptography, which uses algorithms designed to withstand attacks from quantum computers.

• Automation and orchestration: As threats grow in complexity and scale, manual response efforts struggle to keep up. Automation and orchestration can streamline threat detection and response, reducing reaction times from hours to seconds. Automated systems can analyze logs, detect anomalies, and initiate counter-measures instantly, allowing cyber security teams to focus on high-level strategies rather than repetitive tasks.

• AI in security: AI-driven security offers incredible capabilities but must be designed with transparency and ethics. Ethical AI in security ensures that AI-driven decisions are fair, explainable, and bias-free. This approach promotes user trust and accountability, especially in automated security processes.

• Advanced threat modeling techniques: Advanced threat modeling techniques proactively anticipate and counteract potential security risks. Leveraging AI and machine learning for predictive threat detection brings new insight to threat modeling. By analyzing patterns in historical data, AI/ML models can identify trends, spot emerging threats, and even predict potential vulnerabilities before they’re exploited.

In addition to security measures or practices during the design phase, we should secure the software system by implementing secure practices for the complete software development life cycle (SDLC).

Integrating security into the SDLC#

Securing the software development life cycle (SDLC) is essential because it ensures that security is built into software from the ground up, not just as an afterthought.

When security is prioritized at every stage, from planning to testing and deployment, it becomes far easier to catch and address vulnerabilities before they reach production. By embedding security into the SDLC, developers create software resilient to threats, protecting the end-users and the organization from potential breaches.

Let’s discuss how we can opt for secure coding practices.

Secure coding practices#

Secure coding practices are like a strong foundation of a building. When developers write code, they’re not just creating features—but defenses.

Each line has to hold up against anyone trying to break in. Developers have to think like attackers to spot weak points. Imagine you’re trying to break into your system; where would you look first? What shortcuts would you try to slip through?

• Input validation: Picture every form and input field as an entry point to our secure system. If we let just anyone or anything walk in unchecked, we’re practically inviting trouble. Whether it’s a name, email, or file, each piece gets scrutinized to ensure it won’t cause havoc once inside. Validating input is necessary to prevent cross-site scripting (XSS)A security vulnerability that allows attackers to inject malicious scripts into webpages viewed by other users, potentially compromising user data. and SQL injectionA code injection technique that exploits vulnerabilities in an application's database query execution, allowing attackers to manipulate or access sensitive data stored in the database..

• Keep the keys safe: Leaving sensitive info like passwords in code is like hiding the building’s master key in plain sight. Always store keys securely.

• Error handling: Error messages are like signals, providing inside information about the system’s workings. A detailed message can reveal too much about the inner workings, giving clues about weak spots. We should keep the messages simple and log the details privately, capturing details securely without letting attackers read between the lines.

Let’s summarize security measures against different types of attacks in the following table:

Next steps for building secure systems#

Protecting a system requires a layered, ever-evolving approach. From securing your data and network to safe third-party integrations and proactive threat modeling, every layer strengthens your defenses.

But as technology evolves, so do the questions:

• How can we balance automation with human oversight in security?

• Are we ready for the challenges of quantum threats?

• How can we prioritize defenses without overcomplicating systems?

The key is staying proactive: adapting to new threats, embracing innovation like quantum-resistant security and ethical AI, and constantly refining your defenses.

Constant vigilance!

Want to learn more about security in System Design? Deepen your expertise and learn to harness machine learning in these courses: