  Deep learning models are widely deployed in many applications, such as object
detection in various security fields. However, these models are vulnerable to
backdoor attacks. Most backdoor attacks were intensively studied on classified
models, but little on object detection. Previous works mainly focused on the
backdoor attack in the digital world, but neglect the real world. Especially,
the backdoor attack's effect in the real world will be easily influenced by
physical factors like distance and illumination. In this paper, we proposed a
variable-size backdoor trigger to adapt to the different sizes of attacked
objects, overcoming the disturbance caused by the distance between the viewing
point and attacked object. In addition, we proposed a backdoor training named
malicious adversarial training, enabling the backdoor object detector to learn
the feature of the trigger with physical noise. The experiment results show
this robust backdoor attack (RBA) could enhance the attack success rate in the
real world.
