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BackWhat is HTTP flood?
HTTP flood is a denial-of-service attack that overwhelms a web server, application, or API by sending a large volume of seemingly legitimate HTTP requests. Instead of relying on malformed packets, an HTTP flood abuses normal web behavior, such as repeated GET or POST requests, until the target slows down, times out, or becomes unavailable.
Because the requests can look like real user traffic, HTTP flood attacks are often harder to filter than simple network-layer floods. They target the application layer, where websites process sessions, queries, logins, search actions, carts, forms, and dynamic content.
How the attack works
Attackers use botnets, compromised devices, proxy networks, or automated scripts to generate more requests than the application can handle. The goal is to consume web server threads, CPU, database connections, cache capacity, or backend application resources.
The attack may focus on lightweight pages at massive scale or on expensive actions that force the server to perform heavier processing. For example, repeatedly requesting search results, login endpoints, or dynamically generated pages can cause more damage than repeatedly loading a static image.
| Type | What it does |
|---|---|
| GET flood | Sends repeated requests to retrieve pages, files, or API responses. |
| POST flood | Submits data repeatedly, often forcing validation, database writes, or form handling. |
| Low-and-slow HTTP flood | Uses slower request patterns to avoid obvious traffic spikes and detection rules. |
Why HTTP flood is difficult to detect
The flood traffic may use valid methods, headers, cookies, user agents, and request paths. Attackers can also rotate IP addresses, mimic browser behavior, and vary request timing to blend with normal traffic.
This makes simple IP blocking or rate limits less reliable. Defenders need to look at request intent, session behavior, endpoint sensitivity, traffic baselines, and whether users complete normal journeys after making requests.
Business impact of HTTP flood attacks
It can cause website downtime, degraded application performance, failed transactions, support spikes, and reputational damage. For businesses that depend on SaaS portals, ecommerce platforms, customer dashboards, or public APIs, even partial slowdown can affect revenue and service trust.
It may also distract security teams while adversaries attempt credential attacks, vulnerability probing, or data scraping elsewhere.
How organizations reduce HTTP flood risk
Effective protection combines traffic filtering with application-aware controls. Common defenses include web application firewalls, DDoS protection services, bot detection, adaptive rate limiting, caching, CDN shielding, challenge-response checks, and monitoring for abnormal endpoint usage.
Endpoint and device management also matters. Platforms such as Hexnode can help organizations keep managed devices updated, compliant, and less likely to become part of attack infrastructure through poor configuration or outdated software.
FAQs
It is a type of DDoS attack when it uses many distributed sources. A smaller HTTP flood can also come from fewer systems or automated scripts.
No. HTTPS encrypts traffic in transit, but it does not prove that a request is harmless. Attackers can flood HTTPS endpoints too.
Web server logs, WAF logs, CDN logs, application logs, authentication logs, and API gateway metrics help identify targeted endpoints, request rates, user agents, and source patterns.