CAPEC 275

An attacker serves content whose IP address is resolved by a DNS server that it controls and after initial contact by a web browser or similar client it changes the IP address to which its name resolves to an address within the target browser's organization that is not publicly accessible, thus allowing the web browser to examine this internal address on its behalf. Web browsers enforce security zones based on DNS names in order to prevent cross-zone disclosure of information. In a DNS binding attack an attacker publishes content on their own server with their own name and DNS server. The first time the target accesses the attacker's content, the attacker's name must be resolved to an IP address. The attacker's DNS server performs this resolution, providing a short Time-To-Live (TTL) in order to prevent the target from caching the value. When the target makes a subsequent request to the attacker's content the attacker's DNS server must again be queried, but this time the DNS server returns an address internal to the target's organization that would not be accessible from an outside source. Because the same name resolves to both these IP addresses, browsers will place both IP addresses in the same security zone and allow information to flow between the addresses. The attacker can then use scripts in the content the target retrieved from the attacker in the original message to exfiltrate data from the named internal addresses. This allows attackers to discover sensitive information about the internal network of an enterprise. If there is a trust relationship between the computer with the targeted browser and the internal machine the attacker identifies, additional attacks are possible. This attack differs from pharming attacks in that the attacker is the legitimate owner of the malicious DNS server and so does not need to compromise behavior of external DNS services.