CVE-2023-20521 — TOCTOU in the ASP Bootloader may allow an attacker with physical access to tampe

TOCTOU in the ASP Bootloader may allow an attacker with physical access to tamper with SPI ROM records after memory content verification, potentially leading to loss of confidentiality or a denial of service.

01What is this vulnerability?

TOCTOU in the ASP Bootloader may allow an attacker with physical access to tamper with SPI ROM records after memory content verification, potentially leading to loss of confidentiality or a denial of service.

02Affected products

Vendor	Product	Versions
AMD	Athlon™ 3000 Series Desktop Processors with Radeon™ Graphics “Picasso” AM4	various
AMD	Ryzen™ Threadripper™ 2000 Series Processors “Colfax”	various
AMD	Athlon™ 3000 Series Mobile Processors with Radeon™ Graphics “Dali”/”Dali” FP5	various
AMD	Athlon™ 3000 Series Mobile Processors with Radeon™ Graphics “Pollock”	various
AMD	Ryzen™ 3000 Series Mobile Processor with Radeon™ Graphics “Picasso” FP5	various
AMD	1st Gen AMD EPYC™ Processors	various
AMD	2nd Gen AMD EPYC™ Processors	various
AMD	3rd Gen AMD EPYC™ Processors	various
AMD	AMD EPYC™ Embedded 3000	various
AMD	AMD EPYC™ Embedded 7002	various
AMD	AMD EPYC™ Embedded 7003	various
AMD	AMD Ryzen™ Embedded R1000	various
AMD	AMD Ryzen™ Embedded R2000	various
AMD	AMD Ryzen™ Embedded V1000	various

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-11-14T18:52:31.662Z
• Last modified: 2024-08-02T09:05:36.873Z

09References

• www.amd.com — https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-4002
• www.amd.com — https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3002
• www.amd.com — https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-5001