It is possible to break through Intel’s innovative security wall, Intel Software Guard Extension (SGX).
SGX is a security feature of Intel processors to protect the privacy and integrity of information and applications on the computer. It is available in all recent Intel processors, and is broadly deployed in personal computers and cloud computing services.
The attack, dubbed Foreshadow, exploits certain weaknesses in the existing mechanisms of Intel CPUs, allowing an attacker to expose private application data and forge computations secured by SGX, said researchers at Technion-Israel Institute of Technology.
Researchers reported Foreshadow to Intel in January this year. Further analysis into the causes of Foreshadow performed by Intel revealed the same hardware flaw enables a number of other attacks. Called Foreshadow – NG, these attacks put in risk the privacy of users of cloud computing systems that use Intel CPUs. Patches that mitigate these attacks have already been released.
The researchers from the Technion are Assistant Prof. Mark Silberstein of the Viterbi Faculty of Electrical Engineering and his graduate student Marina Minkin from the Computer Science Department. They conducted the study together with their colleagues from The University of Adelaide (Australia), The University of Michigan (USA) and KU Leuven (Belgium). Former Technion graduates Ophir Weiss and Assistant Prof. Daniel Genkin were also involved in the research.
SGX is a revolutionary hardware technology that enables creation of secure execution environments, called secure enclaves.
SGX has a wide range of potential applications.
“Let’s say a company such as Netflix is interested in guaranteeing that its customers may watch movies only via Netflix’s own video streaming application to prevent illegal copies of the streamed contents,” Silberstein said. “How to ensure that the client does not hack into the application, dumps its memory, or replaces it with a reverse-engineered version, given that the computer is entirely under her control?”
With SGX, Netflix servers can verify the client application is invoked in a secure enclave that runs genuine Netflix software, and only then start transferring the movie. Moreover, SGX automatically encrypts all the information in the enclave’s memory with a unique key hardware-protected key.
“This way, only the Netflix client, and no other applications on the computer, not even a computer administrator, may access the movie in the computer’s memory, as long as the processor hardware itself is not compromised,” Silberstein said.
SGX is also useful for cloud computing systems that rent remote computers by an hour, because SGX allows their users to trust the computations performed on remote cloud computers as if they were their own. Leading cloud computing vendors including IBM, Google, and Microsoft have already announced products that rely on SGX.
But the Foreshadow attack breaks these essential SGX security guarantees.
Researchers managed to read all the information stored in the enclave – the information the user assumes is confidential. Moreover, Foreshadow compromised the secure storage mechanisms upon which the mechanism for validating the authenticity of a remote enclave is built, enabling the researchers to forge the programs running in the enclave. Foreshadow compromises core security guarantees provided by SGX, toppling large part of the entire SGX ecosystem by exploiting a single critical hardware vulnerability.
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