CVE-2023-37479
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk46th percentile - higher than 46% of all known CVEs
Summary
Open Enclave SDK version 0.19.3 addresses two vulnerabilities. The first concerns improper sanitization of the `MXCSR` register on enclave entry, which can lead to MCDT attacks. The second involves the lack of sanitization of the `RFLAGS.AC` flag, allowing attackers to monitor unaligned memory accesses.
Risk Assessment
Organizations using Open Enclave may be exposed to attacks that exploit incorrect `MXCSR` values and the ability to monitor improper memory accesses, potentially leading to the disclosure of sensitive data.
Recommendation
It is recommended to upgrade to version 0.19.3 and recompile applications against the patched libraries to protect against this vulnerability.
Original NVD description (English source)
Open Enclave is a hardware-agnostic open source library for developing applications that utilize Hardware-based Trusted Execution Environments, also known as Enclaves. There are two issues that are mitigated in version 0.19.3. First, Open Enclave SDK does not properly sanitize the `MXCSR` register on enclave entry. This makes applications vulnerable to MXCSR Configuration Dependent Timing (MCDT) attacks, where incorrect `MXCSR` values can impact instruction retirement by at most one cycle, depending on the (secret) data operand value. Please find more details in the guidance from Intel in the references. Second, Open Enclave SDK does not sanitize x86's alignment check flag `RFLAGS.AC` on enclave entry. This opens up the possibility for a side-channel attacker to be notified for every unaligned memory access performed by the enclave. The issue has been addressed in version 0.19.3 and the current master branch. Users will need to recompile their applications against the patched libraries to be protected from this vulnerability. There are no known workarounds for this vulnerability.