Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability
Cisco disclosed a UEFI Secure Boot bypass in UCS servers and UCS-based appliances letting authenticated or physically present attackers execute unauthorized software.
Cisco published an advisory for a vulnerability in the UEFI Shell implementation of UCS servers and UCS-based appliances. Memory write commands remain available in the UEFI Shell while Secure Boot is enabled, allowing an attacker to modify UEFI memory and bypass validation checks to run unauthorized software. Exploitation requires either valid credentials for a user or admin account, or unauthenticated physical access to select the UEFI Shell boot option at boot time. The issue affects firmware boot integrity rather than the running operating system.
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