Tallinn Manual on the International Law Applicable to Cyber Warfare by Professor Michael N. Schmitt.
Description from Amazon:
The product of a three-year project by twenty renowned international law scholars and practitioners, the Tallinn Manual identifies the international law applicable to cyber warfare and sets out ninety-five ‘black-letter rules’ governing such conflicts. It addresses topics including sovereignty, State responsibility, the jus ad bellum, international humanitarian law, and the law of neutrality. An extensive commentary accompanies each rule, which sets forth the rule’s basis in treaty and customary law, explains how the group of experts interpreted applicable norms in the cyber context, and outlines any disagreements within the group as to each rule’s application.
A bit pricey, $129.99 (hard cover), $41.59 (Kindle), $58.48 (paperback), but it is rather specialized.
The conventional “laws of war” are designed to favor current sovereign states and their style of warfare. I would not expect eventual “laws of war” for cyberwarfare to be any different.