1. A method for protecting against security threats, the method comprising: with a firewall comprising a non-transitory computer-readable storage medium storing instructions that, when executed by at least one processor of the firewall, are operable to: receive data intended for a recipient behind the firewall, wherein the data comprises a plurality of elements with at least one element comprising a malicious script harboring a security threat; produce a browser rendering of the data, the browser rendering comprising output resulting from execution of the malicious script; reconstruct the data from the browser rendering, wherein reconstructing the data comprises generating reconstructed data in part from the output resulting from execution of the malicious script instead of the malicious script; and pass the reconstructed data from the firewall to the intended recipient.