Tuesday February 12, 2019

Researchers Show Malicious Code Can Escape Intel SGX Enclaves

Today, security researchers published a paper on techniques that can be used to "escape" an Intel Software Guard Extensions enclave on modern CPUs. Sample code for the exploits have already been published on Github, and the researchers note that it was successfully tested on an i7-6700K and an i7-8650U. The Register, who reported on the issue before the paper went up, was told that "experts tend to discount attacks involving enclaves because these locked-down code spaces are more constrained than normal system processes." They also posted a response from Intel, which you can read below:

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Intel is aware of this research which is based upon assumptions that are outside the threat model for Intel SGX. The value of Intel SGX is to execute code in a protected enclave; however, Intel SGX does not guarantee that the code executed in the enclave is from a trusted source. In all cases, we recommend utilizing programs, files, apps, and plugins from trusted sources. Protecting customers continues to be a critical priority for us and we would like to thank Michael Schwarz, Samuel Weiser, and Daniel Grus for their ongoing research and for working with Intel on coordinated vulnerability disclosure.

Intel is technically correct, but that statement doesn't exclude the possibility of unrelated malware using SGX to hide itself. The research paper's second line says that "Intel's threat model for SGX assumes fully trusted enclaves, yet there is an ongoing debate on whether this threat model is realistic." Thanks to cageymaru for the tip.