Biblio

The prevalence of memory corruption bugs in the past decades resulted in numerous defenses, such as stack canaries, control flow integrity (CFI), and memory-safe languages. These defenses can prevent entire classes of vulnerabilities, and help increase the security posture of a program. In this paper, we show that memory corruption defenses can be bypassed using speculative execution attacks. We study the cases of stack protectors, CFI, and bounds checks in Go, demonstrating under which conditions they can be bypassed by a form of speculative control flow hijack, relying on speculative or architectural overwrites of control flow data. Information is leaked by redirecting the speculative control flow of the victim to a gadget accessing secret data and acting as a side channel send. We also demonstrate, for the first time, that this can be achieved by stitching together multiple gadgets, in a speculative return-oriented programming attack. We discuss and implement software mitigations, showing moderate performance impact.

Attacks that leverage USB as an attack vector are gaining popularity. While attention has so far focused on attacks that either exploit the host's USB stack or its unrestricted device privileges, it is not necessary to compromise the host to mount an attack over USB. This paper describes and implements a USB sniffing attack. In this attack a USB device passively eavesdrops on all communications from the host to other devices, without being situated on the physical path between the host and the victim device. To prevent this attack, we present UScramBle, a lightweight encryption solution which can be transparently used, with no setup or intervention from the user. Our prototype implementation of UScramBle for the Linux kernel imposes less than 15% performance overhead in the worst case.