HP has disclosed 16 high-impact UEFI firmware vulnerabilities that could allow threat actors to infect devices with malware that gain high privileges and remain undetectable by installed security software. 

These vulnerabilities affect multiple HP models, including laptops, desktop computers, PoS systems, and edge computing nodes.

These vulnerabilities are separated into three buckets based on the component/feature being exploited:

SMM Callout (Privilege Escalation)

• CVE-2021-39298: callout leading to privilege escalation (CVSS – 7.5)
• CVE-2021-23932: callout leading to privilege escalation (CVSS – 8.2)
• CVE-2021-23933: callout leading to privilege escalation (CVSS – 8.2)

SSM (System Management Module)

• CVE-2021-23924: heap buffer overflow leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23925: memory corruption leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23926: memory corruption leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23927: memory corruption leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23928: memory corruption leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23929: memory corruption leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23930: heap buffer overflow leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23931: heap buffer overflow leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-23934: memory corruption leading to arbitrary code execution(CVSS – 8.2)

DXE (Driver eXecution Environment)

• CVE-2021-39297: stack buffer overflow leading to arbitrary code execution (CVSS – 7.7)
• CVE-2021-39299: stack buffer overflow leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-39300: stack overflow leading to arbitrary code execution (CVSS – 8.2)
• CVE-2021-39301: stack overflow leading to arbitrary code execution (CVSS – 7.7)

Because both DXE and SSM are activated before the operating system starts, any flaws exploited in these components exceed Kernel OS privileges and bypass all protections.

Also, a capable malicious actor could potentially exploit them to implant persistent firmware malware that survives OS updates and bypasses UEFI secure Boot, Intel Boot Guard, and virtualization security solutions.

At this point, the only way to address the security risk is to apply the available firmware updates from HP’s BIOS upgrade portal, or by following these instructions.

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