Understanding the Toughest Layer 7 Attacks and How to Prevent Them

In layer 7 attacks, cyber criminals attempt to take down a target system or service by overwhelming it with traffic. Also called «volumetric» attacks, these work by sending more requests to a server than it can handle. This can cause the system to crash and block real users from accessing the website, app, or service.

Volumetric attacks usually target the network or transport layers (layers 3 and 4) in the Open Systems Interconnection (OSI) Model. However, application layer (layer 7) attacks focus on specific parts of an application or service, like a server running WordPress.

In 2022, Google reported that it had successfully stopped a distributed denial of service (DDoS) attack that was sending 46 million requests per second.

The cost of downtime for enterprises can be as high as $2 million, and DDoS attacks continue to increase in frequency and complexity. Last year, there were twice as many layer 7 DDoS attacks as there were the year before, and there was a 542% increase in these types of attacks overall.

Layer 7 DDoS attacks are an advanced type of denial of service (DoS) attack. They specifically target the application layer by flooding servers or networks with traffic, usually in the form of HTTP requests. For example, an attacker may send tens of thousands of requests per second for a particular Web page or repeatedly call an application program interface (API) until the service fails.

These attacks are more complex than other types of DDoS attacks, and they can be difficult to prevent.

Let’s take a closer look at layer 7 attacks, identify the ones that are trickiest to protect yourself from, and go over how you can keep them from getting past your defenses.

Understanding Layer 7 Attacks 

As the top layer of the internet's seven-layer OSI Model, the application layer plays a crucial role in how data is shared with end users. Unfortunately, it’s also a common target for DDoS attacks.

Broadly speaking, there are three main categories of layer 7 attacks:

Type #1. HTTP Flood Attacks

These attacks involve overwhelming a server or network with a large number of HTTP requests, often with the goal of crashing the server or causing it to become unresponsive. To prevent these types of attacks, it’s important to use a Web application firewall (WAF) and implement rate-limiting measures to prevent excessive traffic from reaching the server.

Further Reading: Best Firewalls for Small Businesses in 2023

Type #2. Slowloris Attacks

These involve sending partial HTTP requests to a server in an attempt to keep connections open for as long as possible. This can exhaust the server's resources and make it unavailable to legitimate users. To prevent Slowloris attacks, implement proper connection management (such as with a VPN) and timeout settings on the server.

Further Reading: Best Enterprise VPN Solutions and Vendors

Type #3. HTTP POST Flood Attacks

In these attacks, cybercriminals overwhelm a server or network with a large number of POST requests, often with the goal of consuming all available resources and rendering the server or network unavailable. To prevent HTTP POST Flood attacks, it’s essential to use a Web application firewall (WAF) and implement rate-limiting measures to prevent excessive traffic from reaching the server.

Further Reading: The Most Dangerous Cybersecurity Threats Revealed by 40 IT Experts

The Toughest Layer 7 Attacks

Here are the 5 toughest attacks that target the application layer.

1. Cross-Site Scripting (XSS)

In an XSS attack, a hacker injects malicious code, usually a script, into a website. This code is executed by the user's browser, allowing the attacker to steal sensitive information such as login credentials or personal data. XSS attacks can be carried out through various methods, such as injecting the malicious code into a Web page through a form field or URL parameter.

2. SQL Injection

SQL injection attacks inject malicious code into a website's database through a vulnerable input field. This allows the attacker to gain access to sensitive information, such as user credentials, login information, or any other sensitive data stored in the database.

3. Denial of Service (DoS) Attacks

DoS attacks overwhelms a website or server with traffic through numerous requests. This renders the website inaccessible to real users. These attacks can be easily carried out either by using botnets or through numerous other means of generating large amounts of traffic.

4. Man-in-the-Middle (MitM) Attacks

MitM attacks intercept communication between two parties, thereby allowing the attacker to see or alter the communication. These attacks can be carried out through various methods, such as spoofing a trusted website or using a compromised network.

5. Password Attacks

Password attacks involve attempting to guess or crack a user's password in order to gain unauthorized access to their account. These attacks can be carried out through various methods, such as brute force attacks, dictionary attacks, or using pre-computed hash tables.

How to Prevent the Toughest Layer 7 Attacks

Layer 7 attacks can have serious consequences if successful. However, they can be difficult to detect and can bypass traditional security measures that focus on lower layers of the OSI model.

If an attacker is successful in carrying out a layer 7 attack, they may be able to gain unauthorized access to sensitive information, such as usernames and passwords or personal data like financial or medical records.

This can lead to serious data breaches, significant financial losses, and damage to a company's reputation. Additionally, these types of attacks can disrupt the operation of a website or server, causing inconvenience and loss of revenue for the affected business.

Preventing layer 7 attacks is therefore crucial in order to protect sensitive information, maintain the integrity and availability of systems, and prevent financial losses.

Here are some best practices to help prevent the toughest layer 7 attacks:

1. Ensure Optimum Configuration of Network Devices

Properly configuring firewalls and routers can be an effective line of defense against DDoS attacks. Administrators can specify rules for request filtering using DDoS technologies and enable the implementation of custom rules to facilitate interaction with DDoS tools. Using next-generation firewalls that employ artificial intelligence (AI) to recognize DDoS attack patterns can also be beneficial.

Further Reading: Machine Learning and Artificial Intelligence in Cybersecurity

2. Monitor and Control Security Updates

Attackers search for vulnerabilities in networking hardware and protocols, so it's important to ensure that all network-connected servers and devices are running the latest security updates. Automated patch management can help with this. It's also important to stay informed about new vulnerabilities that may be disclosed by service providers.

3. Have Server Redundancy and Use CDN

Using several dispersed servers, or distributed servers, can make it difficult for a hacker to target all of them at once. If one server is successfully targeted with a DDoS attack, the others can still function and absorb the increased traffic until the targeted system is brought back online.

Hosting servers in data centers and colocation facilities in multiple countries can also help prevent network congestion or single points of failure. Another option is to use a content delivery network (CDN), which can distribute the load across multiple servers.

4. Limit Network Broadcasting

Hackers may send requests to every device connected to your network in order to increase the impact of a DDoS attack. Limiting network broadcasting between devices can help block this strategy. It's also a good idea to consider limiting or turning off broadcast forwarding and to instruct staff to turn off the Echo-Chargen services when possible.

5. Enable Real-Time Visibility and Alerts

Having real-time visibility and alerts can be an effective way to prevent issues. Continuously monitoring your traffic allows you to have a clear understanding of the normal activity your application receives. This can make it easier to spot any unusual, potentially malicious spikes in traffic. With real-time alerts, you can stay informed about any abnormalities in traffic and take appropriate action.

6. Use Rate Limiting and Firewalls

Rate limiting is a technique that limits the number of requests that a server will accept from a single source in a given time period. This can help prevent an attacker from overwhelming your server with too many requests. Firewalls can block incoming traffic that is not allowed by your security rules, which can help prevent a DDoS attack.

Further Reading: Common Types of Network Vulnerabilities and Threats

7. Have a Response Plan in Place

Having a response plan such as Disaster Recovery Plan (DRP) and Business Continuity plan in place for responding to a DDoS attack can help you quickly and effectively mitigate the attack and minimize the impact on your website or online service.


It's important to take a proactive approach to preventing layer 7 attacks, as they can be particularly challenging to defend against. These types of attacks can bypass traditional security measures that focus on lower layers of the OSI model. To prevent these types of attacks, it is important to have robust security measures in place, such as application firewalls and input validation.

It is also advisable to regularly update software and use strong, unique passwords and multi-factor authentication to prevent these types of attacks. A password manager allows you to use complex passwords without forgetting them.

Additionally, educating employees on how to identify and prevent layer 7 attacks can be an effective measure, as generally humans are the weakest link when it comes to cybersecurity. It’s important to stay vigilant and proactive in order to defend against these types of attacks, as they can have serious consequences if successful.

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