As cyberattack methods continue to evolve, the security of DNS resolution has drawn increasing attention. DNS hijacking and man-in-the-middle attacks are two common and potentially devastating cybersecurity threats. They can not only lead users to malicious websites but also steal sensitive user information.

　　DNS is a system that converts domain names into IP addresses, allowing users to access internet resources by entering easily memorable domain names. However, DNS resolution itself has inherent security risks, primarily manifesting in DNS hijacking, man-in-the-middle attacks, and DNS cache poisoning, which we will discuss below.

　　How DNS hijacking works and how to prevent it:

　　DNS hijacking occurs when an attacker uses various means to redirect a user's DNS request to an untrusted server, thereby directing the user to a malicious website. DNS hijacking typically occurs in the following forms:

　　1. DNS query tampering: Attackers intercept DNS requests during transmission and redirect them to a malicious DNS server, thereby obtaining the user's IP address and manipulating the response. This method can be used for advertising fraud, phishing attacks, and other purposes.

　　2. DNS response forgery: During the DNS response process, attackers forge DNS responses and send them to the user, thereby tampering with the DNS resolution results. For example, an attacker can forge an IP address to redirect user requests to a phishing website.

　　Preventing DNS hijacking:

　　Use a secure DNS server: Choose a trusted public DNS service provider, which typically offers better security and protection.

　　1. Enable DNSSEC: DNSSEC is a technology that cryptographically verifies that DNS responses originate from a legitimate source, effectively preventing DNS response forgery. DNSSEC allows DNS servers to verify the integrity and authenticity of response data, preventing attackers from tampering with DNS data.

　　2. Use DoH or DoT: These two protocols encrypt DNS queries and responses, preventing DNS requests from being eavesdropped or tampered with during transmission. By using an encrypted channel, attackers cannot easily perform man-in-the-middle attacks on DNS requests.

　　3. Configure DNS query log auditing: Regularly review DNS logs to identify unusual traffic or tampering. When anomalies are detected, immediate action can be taken to prevent further attacks.

　　Man-in-the-middle (MITM) attacks and their prevention:

　　A man-in-the-middle attack is an attack in which an attacker intervenes between a user and a DNS server. Attackers intercept and tamper with communication data, redirecting user requests to malicious servers or phishing websites. This type of attack typically occurs on public networks (such as Wi-Fi hotspots) or through unencrypted DNS queries.

　　How a man-in-the-middle attack works:

　　An attacker intercepts DNS requests and responses, altering the DNS data or directly redirecting it to a forged server. When a user attempts to access a website, the attacker redirects them to a malicious site, where they can steal sensitive data such as login credentials and bank card information.

　　How to prevent man-in-the-middle attacks:

　　1. Use HTTPS: The HTTPS protocol encrypts communications between users and websites using SSL/TLS. Even if an attacker intercepts data packets, they cannot decrypt the contents. Enforcing HTTPS effectively prevents MITM attacks.

　　2. Enable HTTP Strict Transport Security (HSTS): HSTS is a mechanism that instructs browsers to use HTTPS to access websites, preventing the use of the insecure HTTP protocol in compromised network environments.

　　3. Use DoH: By using the DoH protocol, DNS requests are encrypted and transmitted over HTTPS, preventing man-in-the-middle attackers from intercepting DNS queries. DoH ensures that DNS requests cannot be intercepted or tampered with by third parties.

　　4. Verify SSL Certificates: When visiting a website, always ensure that the SSL certificate is valid and issued by a trusted certificate authority. If the website's SSL certificate is invalid or self-signed, users should avoid entering any sensitive information.

　　DNS Cache Poisoning and Prevention:

　　DNS cache poisoning occurs when an attacker injects forged DNS records into the DNS cache, causing users to visit manipulated IP addresses. This attack is extremely harmful and can cause the site a user visits to become a malicious site controlled by the attacker.

　　How DNS Cache Poisoning Works:

　　An attacker sends forged DNS responses to a DNS server in order to deceive it. Since DNS servers cache DNS records, an attacker can forge and cache these responses, disrupting user DNS resolution for a period of time. This can result in users being directed to malicious websites designated by the attacker.

　　Methods to Prevent DNS Cache Poisoning:

　　1. Enable DNSSEC: DNSSEC encrypts DNS records, ensuring the authenticity of DNS responses. Enabling DNSSEC effectively prevents attackers from forging DNS responses and reduces the risk of DNS cache poisoning.

　　2. Set an appropriate cache expiration time (TTL): The TTL controls how long DNS records are cached on the DNS server. If the TTL is set too long, attackers have more time to launch attacks. Therefore, a reasonable TTL value should be set to reduce the risk of cache poisoning.

　　3. Use DNS pollution detection tools: Regularly use DNS pollution detection tools to detect DNS record tampering. If anomalies are detected, appropriate measures can be taken to restore normal DNS records.

　　The security of DNS resolution directly impacts the online experience and security of internet users. By implementing a series of effective protective measures, such as enabling DNSSEC, using DoH, and configuring secure DNS servers, the risk of DNS hijacking and man-in-the-middle attacks can be significantly reduced. As internet technology continues to evolve, we must remain vigilant to new threats to DNS resolution security and take timely protective measures to ensure network security and stability.