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Sažetak
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An adversary serves content whose IP address is resolved by a DNS server that the adversary controls. After initial contact by a web browser (or similar client), the adversary changes the IP address, to which its name resolves, to an address within the target organization that is not publicly accessible. This allows the web browser to examine this internal address on behalf of the adversary. Web browsers enforce security zones based on DNS names in order to prevent cross-zone disclosure of information. In a DNS binding attack, an adversary publishes content on their own server with their own name and DNS server. The first time the target accesses the adversary's content, the adversary's name must be resolved to an IP address. The adversary's DNS server performs this resolution and provides 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 adversary's content, the adversary'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 adversary can then use scripts in the content the target retrieved from the adversary in the original message to exfiltrate data from the named internal addresses. This allows adversaries 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 adversary identifies, additional attacks are possible. This attack differs from pharming attacks in that the adversary is the legitimate owner of the malicious DNS server and so does not need to compromise behavior of external DNS services.
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