Help Center/ Cloud Firewall/ Best Practices/ Using CFW to Defend Against Network Attacks/ Using CFW to Defend Against Suspicious DNS Activities
Updated on 2024-10-10 GMT+08:00
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Using CFW to Defend Against Suspicious DNS Activities

You can use CFW to defend against suspicious DNS activities.

Application Scenarios

DNS is a basic and important part of most Internet requests. Once the DNS system is attacked, network services will be severely affected. Therefore, it is important to ensure DNS security. CFW provides intrusion prevention rules for detecting suspicious DNS activities. When CFW detects suspicious DNS activity intrusions, it can block intrusion activities and attack traffic in real time.

What Is a Suspicious DNS Activity?

A domain name system (DNS) is a query and conversion system used to convert domain names into IP addresses for computer connections. When a user enters the domain name of a website in the browser, the browser sends a domain name resolution request to the DNS server. The DNS server returns the IP address corresponding to the domain name. The user can obtain the corresponding website resource based on the IP address.

Suspicious DNS activities refer to abnormal DNS requests or responses over the network. Attackers exploit DNS defects or send excessive requests to attack DNS. As a result, the DNS sends abnormal requests or responses, causing domain name resolution errors, resolution timeout, or DNS breakdown. This affects user experience and may also bring serious consequences such as economic losses and even legal liabilities.

Common Suspicious DNS Activities and Their Harms

Common suspicious DNS activities and their impacts include but are not limited to the following:
  • DNS cache poisoning: An attacker exploits the vulnerabilities of a DNS server to take over the DNS server. By tampering with the cache of the DNS server, the attacker redirects user access to malicious websites and launches attacks such as phishing and malware download.
  • DNS buffer overflow: An attacker exploits the vulnerabilities of the DNS server to send a large amount of malicious data to the cache of the server. As a result, the cache overflows and the malicious data overwrites the original valid data, causing attacks such as DNS response tampering, traffic redirection, and man-in-the-middle attacks.

How to Defend Against Suspicious DNS Activities

  1. Log in to the management console.
  2. Click in the upper left corner of the management console and select a region or project.
  3. In the navigation pane on the left, click and choose Security & Compliance > Cloud Firewall. The Dashboard page will be displayed.
  4. (Optional) Switch firewall instance: Select a firewall from the drop-down list in the upper left corner of the page.
  5. In the navigation pane, choose Attack Defense > Intrusion Prevention. Click View Effective Rules under Basic Protection. The Basic Protection tab is displayed.
  6. Filter the rules for defending against suspicious DNS activities. In the filter above the list, select Suspicious-DNS-Activity from the Attack Types drop-down list.
  7. Enable protection in batches. Select multiple rules at a time and click Intercept.

    Intercept: The firewall records the traffic that matches the current rule in attack event logs and blocks the traffic.