Processor vulnerability
CVE-2020-0543
Random numbers from RDRAND and RDSEED, and SGX keys from EGETKEY, can be sampled from another core through a staging buffer the cores share.
- Name
- Special Register Buffer Data Sampling
- Also known as
- SRBDS, CrossTalk
- Vulnerability
- Special Register Buffer Data Sampling
- Kind
- Data sampling
- CVE published
- 2020-06-15 CVE record
- Advisories
- INTEL-SA-00320
- Linux reports it in
srbds
RDRAND and RDSEED read the processor’s random number generator, and
EGETKEY derives SGX keys, through accesses to registers outside the
core. Their results travel through a staging buffer that all cores
share, where the MDS sampling techniques can read them from another
core or thread. An attacker can so learn the random numbers another
program uses for keys.What the sources say of each microarchitecture. Intel’s list gives each CPUID family, model and stepping it covers, with Intel’s mitigation for it (Software, MCU for a microcode update, or Hardware).
Affected processors
5 of the 28 microarchitectures listed are affected in all or some of their models.
| Microarchitecture | Status | Detail | Source |
|---|---|---|---|
| Skylake | Affected | 06_5EH stepping 3 (1. Skylake Xeon E3 - 2. Skylake H - 3. Skylake S): MCU+Software | Intel’s list |
| Kaby Lake | Affected | 06_8EH stepping 9 (1. Amber Lake-Y - 2. Kaby Lake U - 3. Kaby Lake U23e - 4. Kaby Lake Y): MCU 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_9EH stepping 9 (1. Kaby Lake S - 2. Kaby Lake Xeon E3): MCU+Software | Intel’s list |
| Coffee Lake | Affected | 06_8EH stepping A (1. Coffee Lake U43e - 2. Whiskey Lake): MCU+Software 06_8EH stepping B (Whiskey Lake U): MCU+Software 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_9EH stepping A (Coffee Lake H): MCU+Software 06_9EH stepping C (Coffee Lake S): MCU+Software 06_9EH stepping D (1. Coffee Lake H - 2. Coffee Lake Xeon E - 3. Coffee Lake S): MCU+Software | Intel’s list |
| Ivy Bridge | Some models | Linux 7.3 lists INTEL_IVYBRIDGE in cpu_vuln_blacklist with SRBDS | Linux 7.3 |
| Comet Lake | Some models | 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_A5H stepping 2 (Comet Lake H): Not Affected 06_A5H stepping 3 (Comet Lake-S): Not Affected 06_A5H stepping 5 (Comet Lake-S): Not Affected 06_A6H stepping 0 (Comet Lake U62): Not Affected 06_A6H stepping 1 (Comet Lake U62): Not Affected | Intel’s list |
| Haswell | Not affected | 06_3FH stepping 2 (Haswell Server EP/EP4S): Not Affected 06_3FH stepping 4 (Haswell Server EX): Not Affected | Intel’s list |
| Broadwell | Not affected | 06_4FH stepping 1 (1. Broadwell Server E/EP/EP4S - 2. Broadwell Server EX): Not Affected 06_56H stepping 3 (Broadwell DE V2 - V3): Not Affected 06_56H stepping 4 (Broadwell DE Y0): Not Affected 06_56H stepping 5 (Hewitt Lake (Broadwell DE)): Not Affected | Intel’s list |
| Ice Lake (client) | Not affected | 06_7EH stepping 5 (Ice Lake U - Ice Lake Y): Not Affected | Intel’s list |
| Tiger Lake | Not affected | 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 2 (1. Tiger Lake U Refresh - 2. Tiger Lake H35): Not Affected 06_8DH stepping 1 (Tiger Lake H): Not Affected 06_8DH stepping 1 (Tiger Lake H): Not Affected | Intel’s list |
| Alder Lake | Not affected | 06_97H stepping 2 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Catlow (Golden Cove)): Not Affected 06_9AH stepping 3 (1. Alder Lake H (Golden Cove - Gracemont) - 2. Alder Lake P (Golden Cove - Gracemont)): Not Affected 06_9AH stepping 4 (Alder Lake U (Golden Cove - Gracemont)): Not Affected | Intel’s list |
| Rocket Lake | Not affected | 06_A7H stepping 1 (Rocket Lake): Not Affected | Intel’s list |
| Raptor Lake | Not affected | 06_B7H stepping 1 (1. Raptor Lake S - 2. Raptor Lake HX (Raptor Cove/Gracemont)): Not Affected 06_B7H stepping 1 (Catlow (Raptor Cove)): Not Affected 06_BAH stepping 2 - 3 - 8 (1. Raptor Lake P - 2. Raptor Lake H + refresh - 3. Raptor Lake U + refresh (Raptor Cove/Gracemont)): Not Affected 06_BFH stepping 2 - 5 (Raptor Lake S (Raptor Cove/Gracemont)): Not Affected | Intel’s list |
| Meteor Lake | Not affected | 06_AAH stepping 4 (Meteor Lake U/H/PS (Redwood Cove - Crestmont)): Not Affected | Intel’s list |
| Arrow Lake | Not affected | 06_B5H stepping 0 (Arrow Lake U (Redwood Cove - Crestmont)): Not Affected 06_C5H stepping 2 (Arrow Lake H (Lion Cove - Skymont)): Not Affected 06_C6H stepping 2 (Arrow Lake H/HX/S/S Plus (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Lunar Lake | Not affected | 06_BDH stepping 1 (Lunar Lake (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Panther Lake | Not affected | 06_CCH stepping 2 - 3 (Panther Lake (Cougar Cove - Darkmont)): Not Affected | Intel’s list |
| Skylake-SP | Not affected | 06_55H stepping 3 (Skylake Server): Not Affected 06_55H stepping 4 (1. Skylake Server - 2. Skylake D/Bakerville): Not Affected | Intel’s list |
| Cooper Lake | Not affected | 06_55H stepping B (Cooper Lake): Not Affected | Intel’s list |
| Ice Lake (server) | Not affected | 06_6AH stepping 6 (Ice Lake Xeon-SP): Not Affected 06_6CH stepping All (Ice Lake Xeon D (Idaville)): Not Affected | Intel’s list |
| Emerald Rapids | Not affected | 06_CFH stepping 2 (Emerald Rapids (Raptor Cove)): Not Affected | Intel’s list |
| Sapphire Rapids | Not affected | 06_8FH stepping 5 - 6 - 7 - 8 (1. Sapphire Rapids - 2. Sapphire Rapids Edge Enhanced (Golden Cove)): Not Affected 06_8FH stepping 5 - 6 - 8 (Sapphire Rapids (Golden Cove) - Sapphire Rapids HBM): Not Affected | Intel’s list |
| Granite Rapids | Not affected | 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids R1S (Redwood Cove)): Not Affected 06_AEH stepping 1 (Granite Rapids D (Redwood Cove)/Kaseyville): Not Affected | Intel’s list |
| Sierra Forest | Not affected | 06_AFH stepping 3 (Sierra Forest (Crestmont)): Not Affected | Intel’s list |
| Clearwater Forest | Not affected | 06_DDH stepping 1 (Clearwater Forest (Darkmont)): Not Affected | Intel’s list |
| Goldmont | Not affected | 06_5CH stepping A (Apollo Lake): Not Affected 06_5FH stepping All (Denverton (Goldmont)): Not Affected | Intel’s list |
| Goldmont Plus | Not affected | 06_7AH stepping 8 (Gemini Lake): Not Affected | Intel’s list |
| Tremont | Not affected | 06_86H stepping 5 (Snow Ridge BTS (Tremont)): Not Affected 06_86H stepping 7 (Parker Ridge / Snow Ridge NS/NX/BTS): Not Affected 06_96H stepping All (Elkhart Lake (Tremont)): Not Affected 06_9CH stepping All (Jasper Lake (Tremont)): Not Affected | Intel’s list |
| Gracemont | Not affected | 06_9AH stepping 4 (Arizona Beach (Gracemont)): Not Affected 06_BEH stepping 0 (Alder Lake N (Gracemont)/Twin Lake): Not Affected | Intel’s list |
Mitigations
- Microcode: Intel's microcode makes RDRAND, RDSEED and EGETKEY overwrite the shared buffer before other cores can reach it, and holds other cores' off-core accesses until then, which makes these instructions slower; bit 0 of IA32_MCU_OPT_CTRL (MSR 123H) turns that off, which Linux does with srbds=off. Instructions: RDRAND, RDSEED. Source.
How to check a machine
On Linux, /sys/devices/system/cpu/vulnerabilities/srbds holds one of these lines:
Not affectedVulnerableVulnerable: No microcodeMitigation: MicrocodeMitigation: TSX disabledUnknown: Dependent on hypervisor status
Related CVEs
- CVE-2022-21127 Special Register Buffer Data Sampling update