Some Intel microprocessors contain a design weakness that allows for an "inverse MDS" style attack to be performed on writes to memory that allows microarchitectural attacks against load stores. This flaw is very difficult to exploit requiring specific gadgets and timing and no microcode updates will be shipped to mitigate this issue. How it works: A target/victim process will later execute these instructions and speculative use the cached values. This allows an attacker to control and steer (speculative) execution, possibly allowing them to trigger the exploit via known gadgets in existing code to leak sensitive data. Due to the fine-grained control, an attacker potentially has (through e.g. return stack steering), they can cause code within a program to execute speculatively, creating new and novel potential leak gadgets. This attack requires the ability for a local attacker to be able to execute code on the system, It is not known to be accessible across a network service at this time.
Acknowledgements: Red Hat thanks Intel and industry partners for reporting this issue.
Affected CPU releases: - 6th Generation Intel® CoreTM Processor Family - 7th Generation Intel® CoreTM Processor Family - 8th Generation Intel® CoreTM Processor Family - 9th Generation Intel® CoreTM Processor Family - 10th Generation Intel® CoreTM Processor Family - Intel® Xeon® Processor E3 v5 Family - Intel® Xeon® Processor E3 v6 Family - Intel® Xeon® Processor E-2100 Family - Intel® Xeon® Processor E-2200 Family
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2020-0551
Statement: CVE-2020-0551 is the CVE assigned specifically to the hardware implementation leading to this flaw. Unlike the L1TF microarchitectural issue, no additional CVE have been assigned at this time to cover operating systems or vmm/hypervisor specific implementations. As this CVE is a flaw in specific hardware, not the operating system kernel, and operating system mitigations are already applied, Red Hat does not list the Red Hat Enterprise Linux kernel package as “affected” by this CVE. This does not imply that the flaw can not be exposed on systems running Red Hat Enterprise Linux on vulnerable hardware, only that the flaws exist in the hardware implementation and no additional changes are deemed necessary or practical to address this flaw at the software layer. Existing mitigations released in Red Hat Enterprise Linux in response to Spectre V1 (https://access.redhat.com/security/vulnerabilities/speculativeexecution), L1TF (https://access.redhat.com/security/vulnerabilities/L1TF) and MDS (https://access.redhat.com/security/vulnerabilities/mds) should already provide significant barrier against exploitation of this attack vector and no new mitigation is planned at this time.
External References: https://access.redhat.com/articles/load-value-injection-flaw https://software.intel.com/security-software-guidance/insights/deep-dive-introduction-speculative-execution-side-channel-methods https://software.intel.com/security-software-guidance/software-guidance https://software.intel.com/security-software-guidance/insights/deep-dive-load-value-injection
Mitigation: For hardware vulnerable to these attacks, there is no known mitigation other than to upgrade to hardware that is not vulnerable to this flaw. Due to the high level of difficulty of the attack, and the performance impact which would be associated with any potential mitigations, there are currently no microcode or software mitigations for this issue other than previously existing Spectre V1 and SMAP mitigations described above. Red Hat doesn't currently have knowledge of any real-world occurrences of this attack, so the risk of attack may be considered low. To further minimize the possibility of attacks related to this and other speculative issues, trusted and untrusted workloads can be isolated on separate systems. For further details about potential mitigations, see Intel's LVI deep dive whitepaper (https://software.intel.com/security-software-guidance/insights/deep-dive-load-value-injection).