Slow Loris attacks are a type of stealthy, low-and-slow layer 7 Distributed Denial of Service (DDoS) attack that targets web servers. Such attacks leverage a simple yet effective technique to overwhelm web servers. Instead of flooding the server with a high volume of traffic, Slow Loris attacks rely on a low-and-slow approach. Attackers send partial HTTP requests, gradually and intermittently sending additional request headers, effectively keeping connections open and tying up server resources.
Impacts of Slow Loris Attacks
Slow Loris attacks can have significant consequences, including:
Service Disruptions:
By exploiting server resource limitations, Slow Loris attacks can exhaust connection and thread pools, leading to service disruptions or even server crashes.
Stealthy Nature:
Slow Loris attacks are challenging to detect as they appear as legitimate client connections. They can fly under the radar of traditional DDoS mitigation systems, prolonging the duration of the attack.
Detecting Slow Loris Attacks
Server Monitoring:
Monitor server performance metrics such as connection counts, CPU usage, and thread pool utilization. Anomalous behavior or sudden spikes in these metrics may indicate a Slow Loris attack.
Web Application Firewall (WAF):
Implement a Web Application Firewall that includes specific rules designed to detect and block Slow Loris attack patterns. WAFs can analyze HTTP request headers and identify suspicious slow request patterns associated with Slow Loris attacks.
Mitigating Slow Loris Attacks
Connection Timeout Settings:
Configure web server settings to reduce connection timeout values. By closing idle connections promptly, server resources can be freed up and made available for legitimate clients.
Load Balancing and Reverse Proxies:
Deploy load balancing mechanisms or reverse proxies to distribute incoming traffic across multiple backend servers. This helps distribute the load and prevents a single server from being overwhelmed by a Slow Loris attack.
Rate Limiting:
Implement rate limiting measures to restrict the number of connections or requests from a single IP address within a specified time frame. This can help mitigate the impact of Slow Loris attacks by limiting the resources consumed by a single attacker.
Intrusion Detection/Prevention Systems (IDS/IPS):
Utilize IDS/IPS solutions that include signatures and heuristics to detect Slow Loris attack patterns. These systems can actively monitor network traffic and block connections exhibiting characteristics of a Slow Loris attack.
Conclusion
Slow Loris attacks pose a significant threat to web servers, exploiting their inherent limitations and stealthily causing service disruptions. By implementing server monitoring, deploying WAFs, optimizing connection timeout settings, employing load balancing mechanisms, and utilizing rate limiting and IDS/IPS solutions, organizations can strengthen their defenses against Slow Loris attacks. Regular software updates further fortify server security. By taking proactive measures and staying vigilant, organizations can safeguard their web applications and maintain uninterrupted service availability in the face of Slow Loris attacks.
