[TOC]
- Title: BackdooRL Backdoor Attack Against Competitive Reinforcement Learning 2021
 - Author: Lun Wang et. al
 - Publish Year: 12 Dec 2021
 - Review Date: Wed, Dec 28, 2022
 
Summary of paper
Motivation
- in this paper, we propose BACKDOORL, a backdoor attack targeted at two player competitive reinforcement learning systems.
 - first the adversary agent has to lead the victim to take a series of wrong actions instead of only one to prevent it from winning.
 - Additionally, the adversary wants to exhibit the trigger action in as few steps as possible to avoid detection.
 
Contribution
- we propose backdoorl, the first backdoor attack targeted at competitive reinforcement learning systems. The trigger is the action of another agent in the environment.
 - We propose a unified method to design fast-failing agent for different environment
 - We prototype BACKDOORL and evaluate it in four environments. The results validate the feasibility of backdoor attacks in competitive environment
 - We study the possible defenses for backdoorl. The results show that fine-tuning cannot completely remove the backdoor.
 
Some key terms
backdoorl workflow

Defense
- one possible defense is to fine-tune (or un-learn) the victim network by retraining with additional normal episodes.
 - Additionally, we notice that even fine-tuning for more epochs cannot further improve the winning rate.