Last up in this theme is intercloud identities, the risks and mitigations of access between cloud providers, from Noam to Han and Ariatan. This talk explored the effects of larger organizations expanding into multi-cloud architectures, ostensibly to improve robustness and availability. Since many of the resources in each cloud environment are services or machine identities, they need longer-lived static secrets to maintain access to their counterparts in other partitions. The protections in place for service accounts differ between cloud providers, both in terms of nomenclature and technical controls. The presenters show that older post-exploitation tools designed to search for single computer keys to cloud infrastructure are seeing increased utility when each system has to maintain access across cloud vendors. The researchers also showed a post-exploitation persistence and stealth technique where multiple identity providers, or IDPs, can be tied together in Okta. Since IDPs do not require domain and email validation for users, the attacker can create accounts mirroring real accounts with the credentials they know. Visibility is lacking for these types of multi-IDP configurations. We want to note that the subtle or not-so nuances of how each cloud handles identities can expose gaps that attackers continue to exploit. Trying to secure and manage two identity providers for a single organization is likely much harder than working to have one IDP federating across clouds, though it will then be a likely single point of failure. And of course, as companies move to multicloud environments, expect to see more novel ways for things to fall apart. Avoid multi-cloud with multiple IDPs for now, as this is fertile ground for issues. Stepping from the present into the future, we'd pivot to new modalities with which to inflict pain, starting with GPU.zip on the side-channel implications of a hardware-based graphical data compression by Yin-Chen Wang et al. This work explored a data-dependent algorithm implemented transparently in hardware, impacting software security. Modern GPUs, both internal and discrete, implement compression of pixel buffers in order to minimize memory bandwidth demands. By reverse engineering a number of vendors' compression schemes and memory access use, the researchers were able to build an SVG proof-of attack that can steal cross-origin pixel data from a target iFrame. The attack was over 90% accurate on all nine tested devices except for a Google Pixel cell phone. The throughput of leaking pixels ranged from 0.2 pixels per second to over 6 pixels per second. As a proof-of this attack was implemented to steal a Wikipedia username from a cross-origin iframe, taking between 30 minutes to almost 4 hours on different systems. Takeaways. While this specific attack is unlikely to be used in anger, it highlights how modern development that isolates and abstracts systems into layers can have security side effects. Improvements to minimize memory bandwidth demands of the hardware layer transparently have a security impact at the software layer, and software without cross-layer visibility will continue to be at risk of these types of attacks. Next is Aquasonic, Acoustic Manipulation of Underwater Datacenter Operations and Resource Management, by Jennifer Sheldon et al. This forward-looking research explored how a potential move to underwater data centers would be impacted by the different acoustic properties of water versus air. Sound travels faster and further in water, opening the door for possible acoustic attacks from a distance. The researchers explored how broadcasting a roughly 5 kHz sound at a submerged server enclosure would impact the server's hard drive. With enough output volume, the frequency wave would cause hard drive heads to resonate, decreasing throughput and eventually, with sufficient power, disabling the drives. As most data centers employ RAID configurations to improve performance and redundancy, especially for difficult-to submerged enclosures, the research then explored how arrays of hard drives could be impacted. Depending on the distance from the enclosure, alignment of the directional speaker and server, power, the research showed the ability to grade or disrupt server operations. Takeaways are the attacks presented in this paper are more in the realm of mission and possible plot than impacting today's data centers. That said, they raise the changing environmental envelope that should be considered when designing complex systems for nontraditional locations. There has been fair number of acoustic side channels to leak information.