DNS Rebinding

Web browsers have a same-origin policy that prevents scripts on one website from accessing resources on another website. A DNS rebinding attack bypasses the same-origin policy by assigning multiple IP addresses to a website domain name.
 First an attacker sets up a malicious website and DNS server. Through phishing techniques or other methods, a victim is tricked into clicking the URL for the malicious website. The browser sends a DNS request for the IP address of the malicious website. The malicious DNS server responds with a valid, external IP address (1) and a very short time-to-live (TTL) value. TTL is the period of time that a browser caches the IP address for a resolved domain name. After the TTL expires, the browser sends another DNS request for the same website. But this time, the malicious DNS server responds with an internal IP address from the victim network (2). The browser does not detect any changes to the website domain name or origin in the URL.The attacker site can now access internal network resources.