Multiple Cisco UCS-Based Products UEFI Secure Boot Bypass Vulnerability

Advisory ID: cisco-sa-20200219-ucs-boot-bypass
First Published: 2020 February 19 16:00 GMT
Workarounds: No workarounds available
Cisco Bug IDs: CSCvn09490 CSCvq27796 CSCvq27803

A vulnerability in the firmware of the Cisco UCS C-Series Rack Servers could allow an authenticated, physical attacker to bypass Unified Extensible Firmware Interface (UEFI) Secure Boot validation checks and load a compromised software image on an affected device. The vulnerability is due to improper validation of the server firmware upgrade images. An attacker could exploit this vulnerability by installing a server firmware version that would allow the attacker to disable UEFI Secure Boot. A successful exploit could allow the attacker to bypass the signature validation checks that are done by UEFI Secure Boot technology and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.
[…]There are no workarounds that address this vulnerability. Cisco has released firmware updates that address this vulnerability.
[…]UEFI Secure Boot is enabled only in a small subset of Cisco UCS-based appliances. For all the other appliances, the feature is not used, so the vulnerability does not apply.

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