New design New threats: From momentary execution to ciphertext side channel in AMD Secure Encrypted Virtualization

Speaker: Mengyuan Li , Ohio State University

Date: Friday, December 10, 2021

Time: 1:00 PM to 2:00 PM Note: all times are in the Eastern Time Zone

Public: Yes

Location: https://mit.zoom.us/j/97527284254

Event Type: Seminar

Room Description:

Host: Srini Devadas, CSAIL

Contact: Kyle L Hogan, Zack Newman, klhogan@csail.mit.edu,zjn@mit.edu

Relevant URL:

Speaker URL: http://web.cse.ohio-state.edu/~li.7533/

Speaker Photo:
None

Reminders to: seminars@csail.mit.edu, li.7533@osu.edu

Reminder Subject: TALK: New design New threats: From momentary execution to ciphertext side channel in AMD Secure Encrypted Virtualization

Abstract:
AMD's Secure Encrypted Virtualization (SEV) is an emerging security feature of modern AMD processors that allows virtual machines to run with encrypted memory and perform confidential computing even with an untrusted hypervisor. SEV is AMD's ambitious movement towards confidential cloud computing and server processor market, which is gaining traction in the cloud industry. Compared to similar technology like Intel Software Guard Extension (SGX), SEV is more advantageous in its ease of adoption without the need of altering software to be protected. So far, SEV has been adopted in Azure Cloud and Google Cloud as a backend of confidential cloud computing services.

Meanwhile, such an audacious threat assumption has been challenged under the microscope with numerous attacks. In this talk, we will present two vulnerabilities in SEV. The first vulnerability is related to SEV's improper use of address space identifier (ASID), which plays a rather important role in VM's isolation about encrypted memory pages, cache lines, and TLB entries. Based on our exploration, we present CrossLine attacks, which exploit a momentary execution to breach the confidentiality and integrity of SEV VMs. The second vulnerability is related to confidential VM's encryption mode, which seems reasonable at first glance. We then introduce a previously unexplored vulnerability of SEV, dubbed ciphertext side channel. Ciphertext side channel allows the privileged adversary to infer the guest VM's execution states or recover certain plaintext. To demonstrate the severity of this vulnerability, we present the CipherLeaks attack, which exploits the ciphertext side channel to steal private keys from the constant-time implementation of the RSA and the ECDSA in the latest OpenSSL library.

Bio:
Mengyuan Li is now a fifth-year PhD candidate at The Ohio State University (OSU), advised by Prof. Yinqian Zhang. His research covers a variety of topics related to cloud security, hardware security, and micro-architectural security (cache/TLB/page). His recent works target at exploring vulnerabilities in confidential VM. He also cooperated closely with AMD Secure Encrypted Virtualization (SEV) team to mitigate some of his findings. Before OSU, Mengyuan graduated from Shanghai Jiao Tong University (SJTU) with the Bachelor's degree of Electronic Engineering in 2016.

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Research Areas:
Security & Cryptography

Impact Areas:
Cybersecurity

See other events that are part of the CSAIL Security Seminar Series 2021.

Created by Kyle L Hogan at Friday, November 19, 2021 at 8:47 AM.