A Slow HTTP Attack is a type of denial-of-service (DoS) attack that aims to disrupt a server's ability to process legitimate requests by sending HTTP requests at an extremely slow rate. These attacks exploit the server's resources by keeping connections open for as long as possible, thereby preventing new connections from being established. Unlike traditional DoS attacks that flood the server with high volumes of traffic, Slow HTTP Attacks use minimal bandwidth, making them difficult to detect and mitigate.

How do Slow HTTP Attacks Work?

Slow HTTP attacks work by exploiting the way web servers handle HTTP requests. Attackers initiate connections to the server and then send HTTP headers or message bodies at an extremely slow rate. This keeps the server waiting for the completion of the request, thereby tying up server resources.

One common method involves sending partial HTTP headers very slowly, as seen in Slowloris attacks. The server keeps the connection open, waiting for the rest of the headers, which never arrive in a timely manner. Another technique, used in R.U.D.Y. attacks, involves sending HTTP POST requests with data transmitted at a snail's pace, keeping the connection open and consuming server resources.

By maintaining these slow connections, the server's resources are gradually exhausted. This prevents the server from processing legitimate requests, effectively causing a denial of service without triggering typical security alerts due to the low bandwidth usage.

What are Examples of Slow HTTP Attacks?

Examples of Slow HTTP attacks include the well-known Slowloris and R.U.D.Y. (R-U-Dead-Yet?) attacks. Slowloris works by connecting to a server and sending partial HTTP headers very slowly, keeping the connection open and consuming server resources. This method effectively ties up the server, preventing it from processing legitimate requests.

R.U.D.Y. attacks, on the other hand, involve generating HTTP POST requests to fill out form fields. The data is sent at an extremely slow rate, causing the server to keep the connection open while waiting for the completion of the data transfer. Both of these techniques exploit the server's resource management, making them effective tools for denial-of-service attacks.

What are the Potential Risks of Slow HTTP Attacks?

The potential risks of suffering a Slow HTTP Attack are significant and multifaceted. Here are some of the key risks:

• Increased Latency: Slow HTTP attacks can cause significant delays in server response times, making it difficult for legitimate users to access services efficiently.

• Service Disruption: By occupying server resources for extended periods, these attacks can lead to prolonged service outages, affecting the availability of critical applications.

• Resource Exhaustion: These attacks consume server resources, such as memory and processing power, which can prevent the server from handling legitimate requests.

• Negative User Experience: Users may experience frustration due to slow or unresponsive services, potentially leading to a loss of customers or clients.

• Risk to Critical Infrastructure: Slow HTTP attacks can severely impact essential services, causing significant downtime and potentially leading to cascading failures across dependent systems.

How can you Protect Against Slow HTTP Attacks?

Protecting against Slow HTTP Attacks requires a multi-faceted approach. Here are some effective strategies:

• Behavioral Analysis: Continuously monitor traffic patterns to identify anomalies that may indicate a slow HTTP attack.

• Real-time Monitoring: Use tools to monitor server resources such as CPU, memory, and connection tables to detect unusual activity.

• Reverse Proxy-Based Protection: Implement reverse proxies to filter and mitigate attacks before they reach the origin server.

• Increase Server Connections: Upgrade server capacity to handle more simultaneous connections, making it harder for attacks to exhaust resources.

• Deploy DDoS Mitigation Solutions: Utilize specialized DDoS protection tools, such as web application firewalls, to detect and block slow HTTP attacks.