  Detecting the salient objects in a remote sensing image has wide applications
for the interdisciplinary research. Many existing deep learning methods have
been proposed for Salient Object Detection (SOD) in remote sensing images and
get remarkable results. However, the recent adversarial attack examples,
generated by changing a few pixel values on the original remote sensing image,
could result in a collapse for the well-trained deep learning based SOD model.
Different with existing methods adding perturbation to original images, we
propose to jointly tune adversarial exposure and additive perturbation for
attack and constrain image close to cloudy image as Adversarial Cloud. Cloud is
natural and common in remote sensing images, however, camouflaging cloud based
adversarial attack and defense for remote sensing images are not well studied
before. Furthermore, we design DefenseNet as a learn-able pre-processing to the
adversarial cloudy images so as to preserve the performance of the deep
learning based remote sensing SOD model, without tuning the already deployed
deep SOD model. By considering both regular and generalized adversarial
examples, the proposed DefenseNet can defend the proposed Adversarial Cloud in
white-box setting and other attack methods in black-box setting. Experimental
results on a synthesized benchmark from the public remote sensing SOD dataset
(EORSSD) show the promising defense against adversarial cloud attacks.
