SIEM + WAF + NGFW: why is combining layers the best strategy against modern attacks?

The cybersecurity landscape has never been more challenging. Sophisticated attacks, increasingly automated and persistent, put companies of all sizes on constant alert. It is no longer enough to rely solely on traditional firewalls or antivirus: criminals exploit application loopholes, configuration vulnerabilities and even human failings to compromise data and operations.

In this context, an essential question arises: how can we mount a truly effective defense against modern threats? The answer lies in a layered strategy, which brings together different technologies with complementary roles. Among them, three key pieces stand out: SIEM (Security Information and Event Management), WAF (Web Application Firewall) and NGFW (Next-Generation Firewall).

On their own, these tools offer important benefits. But when combined, they form a robust barrier, capable of quickly identifying, blocking and responding to attacks that would escape single solutions. In this article, we'll understand the role of each layer and why integrating them is the safest way to tackle today's cybercrime.

The evolution of digital threats

In recent years, we have seen an exponential growth in attacks targeting companies. It's not just about volume, but sophistication:

• Ransomware that spreads quickly and hijacks critical data.
• Zero-day attacks, exploiting flaws still unknown to the manufacturers.
• Exploitation of web applications, such as SQL injection, cross-site scripting (XSS) and session hijacking.
• Distributed denial of service (DDoS) attacks, capable of taking down entire websites and services.
• Internal threats, coming from malicious employees or human failings exploited by social engineering.

In addition, attackers use evasion techniques such as encrypted traffic, dynamic IPs and globally distributed bots, which makes detection difficult.

In this scenario, a single security solution cannot offer total coverage. This is where the layering strategy comes into its own: each technology covers an angle of the defense, drastically reducing the attack surface and increasing the response capacity.

NGFW: the basis of intelligent defense

The Next-Generation Firewall (NGFW) is the evolution of the traditional firewall. More than controlling ports and protocols, it acts in depth on network traffic.

Main features of the NGFW:

• Deep packet inspection (DPI): analyzes the content of traffic, identifying threats hidden in apparently legitimate protocols;
• Intrusion prevention system (IPS): detects and blocks attempts to exploit vulnerabilities;
• Granular application control: defines usage policies for specific applications, increasing security and productivity;
• Support for encrypted traffic: inspects HTTPS communications, where most modern threats hide;
• Network segmentation: creates secure zones that isolate critical environments and reduce the spread of attacks.

The NGFW is essential for creating a perimeter line of defense, blocking attacks before they even reach applications or the end user. It acts as the organization's "gatekeeper", but with enough intelligence to recognize not only who enters, but also the behavior of what passes through the network.

WAF: shielding web applications

If the NGFW protects the perimeter, the Web Application Firewall (WAF) acts directly on the application layer, which today is one of the attackers' favorite targets. After all, web systems concentrate sensitive data and are permanently exposed to the internet.

WAF's main benefits:

• Protection against attacks on web applications: SQL Injection, XSS, Remote File Inclusion, among others;
• HTTP/HTTPS traffic filtering: blocks malicious access and allows only legitimate interactions;
• Mitigation of DDoS attacks targeting applications;
• Analysis of user and bot behavior: differentiates genuine access from suspicious automated activity;
• Regulatory compliance: helps companies meet standards such as PCI-DSS, LGPD and GDPR, which require data protection in transit.

In practice, the WAF acts as a barrier between the user and the application, inspecting each request before it is processed. This prevents malicious code or manipulation attempts from reaching the system.

A practical example: imagine an e-commerce business. Without a WAF, an attacker could try to insert malicious SQL commands into login forms to gain access to the database. With a WAF in place, this type of attempt is intercepted and blocked immediately.

SIEM: the central intelligence of security

While NGFW and WAF have more tactical blocking functions, SIEM (Security Information and Event Management) acts strategically, gathering and analyzing data from the entire IT infrastructure.

What SIEM does:

• Collecting and correlating logs from different sources (firewalls, servers, endpoints, applications, cloud systems);
• Detection of anomalies and advanced threats through real-time analysis;
• Alert automation: sends immediate notifications when a suspicious pattern is identified;
• Support for forensic investigations: provides detailed audit trails to understand the origin and impact of incidents;
• Compliance reports: facilitates auditing and compliance with regulatory standards.

SIEM is the brain of cybersecurity, capable of turning scattered data into actionable insights. It not only detects threats that might otherwise go unnoticed, but also speeds up incident response.

A good example is when SIEM identifies lateral movements: even if an attacker bypasses the NGFW or WAF, SIEM can correlate unusual events and alert the team before the attack causes major damage.

Read more: the-vulnerabilities-most-exploited-by-hackers

The power of combination: SIEM + WAF + NGFW

Separately, each technology already offers significant gains. But it's the integration between SIEM, WAF and NGFW that really creates a cutting-edge defense strategy.

How they complement each other:

• NGFW blocks threats at the network layer.
• WAF protects critical applications against targeted attacks.
• SIEM centralizes information, correlates events and guarantees broad visibility.

When connected, these layers offer

1. Faster and more accurate detection - SIEM receives detailed logs from the NGFW and the WAF, cross-referencing information that might seem harmless in isolation;
2. Automated responses - Integration policies allow the NGFW or WAF to apply immediate blocks when a threat is detected in the SIEM;
3. Reduction of false positives - Cross-analysis between layers reduces unnecessary alarms, optimizing the work of the security team;
4. Resilience against modern attacks - Even if a technique manages to evade the NGFW, it is unlikely to pass through the WAF and, if it does, it will be detected by the SIEM.

This approach is known as defense in depth and is the basis of modern cybersecurity strategies.

Practical examples of layered defense

Scenario 1: Ransomware spreading

An employee receives an email with a malicious link.

• The NGFW identifies suspicious traffic in communication with an external server and blocks it.
• If the malicious file tries to exploit a vulnerability in an application, the WAF intercepts it.
• SIEM correlates the attempts and alerts the team to isolate the affected machine.

Scenario 2: E-commerce injection attack

A hacker tries to exploit a login form.

• The WAF detects attempted SQL Injection and blocks it in real time.
• The NGFW records the origin of traffic and prevents new accesses from the same IP.
• SIEM correlates similar attempts at different times and identifies a coordinated campaign, enabling a preventive response.

Scenario 3: Lateral movement within the network

An attacker gains initial access to an internal machine.

• The NGFW limits access between network segments.
• The SIEM detects lateral movement outside the usage pattern and triggers an alert.
• The WAF protects the database from exploitation attempts, even if the attacker is already inside the perimeter.

Strategic benefits for companies

Adopting a combination of SIEM, WAF and NGFW brings advantages that go beyond technical protection:

• Business continuity: prevents downtime caused by attacks.
• Reputation protection: reduces the risk of data leaks and negative exposure.
• Meeting regulatory requirements: compliance with data protection standards.
• Resource optimization: integration reduces redundancies and improves operational efficiency.
• Scalability: cloud solutions allow protection to keep pace with company growth.

In a market where digital trust is a competitive differentiator, investing in integrated security becomes not only a matter of protection, but also of business strategy.

Conclusion

The fight against cybercrime requires much more than isolated barriers. The combination of SIEM, WAF and NGFW represents a robust approach that unites prevention, detection and response in a continuous cycle of protection.

Companies that adopt this layered strategy are able not only to block more common attacks, but also to identify and react to advanced threats, guaranteeing the continuity of their operations and the protection of their data.

In a scenario where digital attacks are inevitable, the best defense is to be prepared! Learn more!