At the core of internet infrastructure, the DNS system serves as a network traffic navigator, and its security is crucial to the stable operation of the entire network ecosystem. However, this addressing mechanism has also become a hotbed for cyberattacks. Various sophisticated hijacking techniques continue to threaten the network security of businesses and individuals. Understanding these attack vectors and establishing effective monitoring and defense systems are key priorities in current network security management.

DNS hijacking essentially modifies the normal domain name resolution process, redirecting users to unexpected server addresses and then performing other illicit operations. Local host hijacking is the most basic form of attack. Attackers modify a device's hosts file or local DNS configuration to redirect specific domain names to malicious IP addresses. This technique has a low technical barrier to entry, but its scope of impact is limited, typically targeting a single device.

Router hijacking expands the scope of attack, targeting core network devices. Attackers exploit weak router passwords or known vulnerabilities to gain control and modify the router's DNS server settings. Once the router is compromised, DNS queries from all devices on the local area network are redirected to the malicious server. According to security monitoring data, over 30% of enterprise networks have experienced router DNS settings tampering, most of which stem from untimely firmware updates or the use of default administrative passwords.

Man-in-the-middle attacks represent a more advanced threat model. Attackers deploy interception devices along network transmission paths and, through techniques such as ARP spoofing or BGP route hijacking, direct DNS query traffic through nodes they control. This attack is difficult for ordinary users to detect because the entire hijacking process occurs at the network level, leaving the user's device configuration appearing completely normal. A data breach at a major financial institution in 2024 stemmed from this type of attack, exposing the information of tens of thousands of customers.

Cache poisoning attacks target intermediate links in the DNS resolution chain. Attackers inject forged resolution records into recursive DNS servers, causing all users who query that server to receive malicious IP addresses. This attack is extremely destructive; a single successful cache poisoning attack can affect tens of thousands of users. The famous Kaminsky vulnerability is a prime example of this type of attack, allowing attackers to inject forged DNS records into recursive servers before the authoritative server's response arrives.

The emerging TLS/SSL certificate spoofing technique combines encryption protocols with DNS hijacking. Attackers use this hijacking to redirect users to servers they control, while providing a seemingly valid SSL certificate to establish an encrypted connection. This attack is highly deceptive, displaying a security lock icon in the user's browser while allowing the attacker to fully monitor all communications.

Detecting DNS hijacking requires a multi-faceted monitoring system. Regularly verifying the accuracy of DNS resolution results is a fundamental detection method. Cross-checking results under different network environments can identify potential resolution anomalies. The following Python code demonstrates a basic DNS validation method:

import dns.resolver

def check_dns_hijacking(domain, expected_ip):

try:

answers = dns.resolver.resolve(domain, 'A')

for rdata in answers:

if str(rdata) != expected_ip:

return True, f"Hijacking detected: {rdata}"

return False, "DNS resolution normal"

except Exception as e:

return True, f"DNS query exception: {str(e)}"

Network traffic monitoring and analysis can uncover more subtle hijacking behaviors. By detecting abnormal DNS query response times, TTL values, or source IP addresses, man-in-the-middle attacks and cache poisoning can be identified. Enterprise-level security systems often deploy DNSSEC validation modules to automatically check digital signatures to ensure the authenticity of resolution results.

Certificate Transparency monitoring is an effective method for combating TLS spoofing. By monitoring public certificate logs, you can promptly identify SSL certificates issued illegally for your domain. Google's Certificate Transparency project provides a comprehensive technical foundation for this. Any certificate issued by a compliant CA is recorded in publicly accessible logs.

On a defensive level, DNSSEC technology provides an end-to-end resolution verification mechanism. It uses digital signatures to ensure that DNS responses have not been tampered with during transmission, allowing recursive servers to verify the authenticity and integrity of response data. While deployment requires specialized technical support, it is currently the most comprehensive DNS security solution.

Encrypted DNS protocols such as DNS over HTTPS and DNS over TLS significantly increase the difficulty of attacks. These protocols encapsulate DNS queries within encrypted connections, effectively preventing network-level eavesdropping and tampering. Major operating systems and browsers now widely support the DoH protocol, and users can enable it with a simple configuration.

Enterprise environments require a multi-layered defense system. A local DNS security gateway can filter malicious queries and block communications with known malicious DNS servers. Network segmentation and strict access controls can limit the internal attack surface and prevent critical devices such as routers from being easily compromised. Regular security awareness training is also crucial, and employees should learn to recognize basic symptoms of network anomalies.

Individual users should also take basic protective measures. Regularly update router firmware and change default passwords, use trusted public DNS services such as Cloudflare or Google DNS, install reliable security software, and keep system patches up to date. These simple measures can prevent most common DNS hijacking attacks.

With the proliferation of IoT devices and 5G networks, DNS security faces new challenges. Smart devices often lack adequate security protections, making them easy targets for attackers to break into home networks. Future developments in DNS security require collaboration among device manufacturers, service providers, and users to build a more comprehensive protection system.

The battle between DNS hijacking and attack and defense is a perennial theme in cybersecurity. Only by deeply understanding the attack mechanisms, establishing comprehensive detection mechanisms, and implementing layered defenses can we maintain the initiative in this invisible battlefield.