DNS Spoofing

DNS Spoofing, also known as DNS cache poisoning, is a type of cyber attack where corrupt DNS data is inserted into the cache of a DNS resolver. This causes the name server to return an incorrect IP address, diverting traffic to the attacker’s computer or any other malicious location.

How DNS Works

When you type a domain name (like www.google.com) into your browser, a DNS query is made to translate this human-readable domain into an IP address. DNS servers resolve this query and send back the corresponding IP address. Attackers take advantage of this trust in the DNS infrastructure to poison the DNS cache.

What is DNS Spoofing?

DNS Spoofing manipulates DNS responses, often by intercepting requests or tricking a DNS server into caching false data. When a user attempts to visit a legitimate site, they are instead redirected to a malicious one, such as a fake login page or malware site.

Techniques Used

• Cache Poisoning: Injecting false DNS records into a resolver’s cache.
• Man-in-the-Middle: Intercepting and altering DNS responses in real-time.
• Compromised DNS Servers: Directly altering records on a DNS server under attacker control.

Risks of DNS Spoofing

• Users can be redirected to phishing sites that look legitimate.
• Malware can be installed unknowingly.
• Corporate credentials and sensitive data can be stolen.
• DNS spoofing can be used in larger attacks like session hijacking and MITM.

How to Prevent DNS Spoofing

• Use DNSSEC: DNS Security Extensions add authentication to DNS responses.
• Clear DNS Cache Frequently: Reduces the time poisoned records remain active.
• Use Secure DNS Services: Providers like Cloudflare and Google offer DNS over HTTPS.
• Keep Software Updated: Prevent known vulnerabilities from being exploited.
• Network Monitoring Tools: Detect anomalies in DNS traffic and alert administrators.

Conclusion

DNS spoofing is a powerful technique that can be used by attackers to silently redirect and compromise users. As a penetration tester or security enthusiast, it's vital to understand how DNS works, how it can be abused, and how to defend against such attacks using technologies like DNSSEC, secure DNS services, and vigilant monitoring practices.