Improper sanitization of MXCSR and RFLAGS in OpenEnclave
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 0.19.3
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- openenclave openenclave
fixed in 0.19.3