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How Can a CDN Help Mitigate Brute Force Attacks?

Rostyslav Pidgornyi
June 20, 2024

A CDN mitigates brute force attacks by providing robust rate limiting and CDNs with strong DDoS protection.

Here is how it works:

Mitigating Brute Force Attacks with a CDN

Brute force attacks attempt to gain unauthorized access by systematically trying various passwords or encryption keys. A CDN (Content Delivery Network) offers multiple security features to protect against these attacks. Here’s how:

1. Rate Limiting 

CDNs use rate limiting to control the number of requests a server can handle within a specified timeframe. This prevents an attacker from making repeated login attempts:

  • Throttling Requests: By limiting the number of requests from a single IP address, CDNs can block excessive attempts to access the system.
  • Dynamic Rules: Advanced CDNs use dynamic rate limiting, adjusting thresholds based on current traffic patterns to ensure legitimate users aren't affected.

When you implement rate limiting, you effectively slow down the attacker, making it impractical for them to continue their brute force attempts. In my experience, this is one of the most effective immediate defenses.

2. IP Blocking and Geo-Fencing 

CDNs can block IP addresses or entire regions known for malicious activities:

  • Blacklist Suspicious IPs: Regularly updated lists of malicious IP addresses help preemptively block potential attackers.
  • Geo-Fencing: Restricting access based on geographic location ensures that only users from specific regions can access sensitive parts of the network.

You can set up geo-fencing rules to block access from regions where you don't expect legitimate traffic. For instance, if your business operates primarily in North America, blocking traffic from regions with high malicious activity can reduce attack vectors significantly.

3. Web Application Firewalls (WAF) 

CDNs integrate WAFs to detect and block malicious traffic:

  • Pattern Recognition: WAFs identify attack patterns, blocking requests that match known brute force attack signatures.
  • Behavior Analysis: Continuous monitoring of traffic behavior helps to differentiate between legitimate users and attackers.

A WAF adds an extra layer of security by analyzing incoming traffic in real-time. When I first integrated a WAF with my CDN, I noticed an immediate drop in suspicious traffic. The WAF identified and blocked multiple brute force attempts that traditional security measures missed.

4. DDoS Protection 

Brute force attacks can sometimes be part of a larger DDoS (Distributed Denial of Service) attack:

  • Traffic Scrubbing: CDNs filter out malicious traffic, ensuring only clean traffic reaches the origin server.
  • Scalability: CDNs can absorb large volumes of traffic, mitigating the impact of a DDoS attack.

When you're under a DDoS attack, the volume of traffic can be overwhelming. CDNs with strong DDoS protection distribute this load, scrubbing malicious requests and keeping your services available. 

I've seen this firsthand during a coordinated attack, where the CDN's DDoS protection was the difference between staying online and going offline.

Benefits of Using a CDN for Security

  1. Reduced Latency: CDNs distribute content closer to the user, reducing latency and improving user experience.
  2. Scalability: CDNs handle traffic spikes, ensuring your website remains accessible during high demand.
  3. Global Reach: With a network of servers worldwide, CDNs provide consistent security and performance for users across different regions.

Implementing CDN Security

  1. Choose a CDN with Strong DDoS Protection: Look for providers with a proven track record in mitigating large-scale attacks.
  2. Configure Rate Limiting Properly: Set appropriate thresholds to balance security and user experience.
  3. Regularly Update Security Protocols: Keep your CDN’s security features up-to-date to defend against evolving threats.