Supply Chain Malware Targets SGX: Take Care of what you Sign

Malware attacks represent a significant part of today's security threats. Software guard extensions (SGX) are a set of hardware instructions introduced by Intel in their recent lines of processors that are intended to provide a secure execution environment for user-developed applications. To our knowledge, there was no serious attempt yet to overcome the SGX protection by leveraging the software supply chain infrastructure, such as weaknesses in the development, build or signing servers. While SGX protection does not specifically take into consideration such threats, we show in the current paper that a simple malware attack exploiting a separation between the build and signing processes can have a serious damaging impact, practically nullifying the SGX integrity protection measures. Finally, we also suggest some possible mitigations against the attack.