Some also have suggested Letters of Marque might be a legal mechanism for such action (which are like a government license to take actions attacking or capturing enemies) or providing an exemption from the CFAA to go after attackers.

FORBES: Caution: Active Response to Cyber Attacks Has High Risk

Even though Article 1 of the U.S. Constitution allows Congress to issue Letters of Marque, they were forbidden in the 1856 Paris Declaration, which as been accepted as customary international law. (Theodore Richard produced an excellent journal paper on this topic analyzing the use of private security providers for piracy).

FORBES: Caution: Active Response to Cyber Attacks Has High Risk