In a crawler attack and an HTTP flood attack, the attacker simulates the behavior of legitimate users when sending requests to the web server. However, the two types of attacks use different techniques and have different characteristics and purposes.
Crawler attacks:
A crawler attack refers to the use of automated bots or scripts to crawl and scrape data from a website without permission. This type of attack can exploit business logic vulnerabilities to obtain illegal gains, such as occupying airline seats, scalping items on e-commerce platforms, brute-forcing account databases, overwhelming core interfaces with requests, manipulating ticket or reward point systems, and engaging in other forms of business fraud. One characteristic of crawler attacks is that they target interfaces with specific business functions, such as logon interfaces, SMS verification code interfaces, ticket inquiry interfaces, and patent search interfaces. In most cases, crawler attacks regulate the rate of data gathering to prevent overwhelming the target website. These attacks aim to mimic the browsing behavior of legitimate users and do not request page resources at an excessive frequency. In most cases, the IP sources of crawler attacks originate from malicious crawler IP intelligence databases, public cloud platforms, and IP repositories of data centers.
HTTP flood attacks
An HTTP flood attack is a type of Distributed Denial of Service (DDoS) attack. The attacker sends seemingly legitimate HTTP requests to attack a web server or application. These requests are designed to consume a large amount of resources on the server, which overwhelms and prevents the system from processing legitimate traffic. The end goal of an HTTP flood attack is to cause the service to significantly slow down or crash. Compared with a crawler attack, an HTTP flood attack is intentionally malicious and makes it difficult to distinguish between legitimate traffic and attack traffic. An HTTP flood attack is executed in a short period of time with high intensity to cause a denial of service. For example, the attacker repeatedly refreshes a page or submits a ticket in a short period of time.
In summary, the objective of a crawler attack is to gather sensitive information about a website, whereas an HTTP flood attack is a targeted, malicious attempt to disable a website. You can use Alibaba Cloud Web Application Firewall (WAF) to defend against crawler attacks and HTTP flood attacks to ensure the security and availability of your website. For more information, see Configure HTTP flood protection rules to defend against HTTP flood attacks and Enable and configure the bot management module.