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Lord of the x86 Rings: A Portable User Mode Privilege Separation Architecture on x86

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conference contribution
posted on 2023-11-29, 18:08 authored by Hojoon Lee, Chihyun Song, Brent Byunghoon Kang
Modern applications often involve processing of sensitive information. However, the lack of privilege separation within the user space leaves sensitive application secret such as cryptographic keys just as unprotected as a "hello world" string. Cutting-edge hardware-supported security features are being introduced. However, the features are often vendor-specific or lack compatibility with older generations of the processors. The situation leaves developers with no portable solution to incorporate protection for the sensitive application component. We propose LOTRx86, a fundamental and portable approach for user-space privilege separation. Our approach creates a more privileged user execution layer called PrivUser by harnessing the underused intermediate privilege levels on the x86 architecture. The PrivUser memory space, a set of pages within process address space that are inaccessible to user mode, is a safe place for application secrets and routines that access them. We implement the LOTRx86 ABI that exports the privcall interface to users to invoke secret handling routines in PrivUser. This way, sensitive application operations that involve the secrets are performed in a strictly controlled manner. The memory access control in our architecture is privilege-based, accessing the protected application secret only requires a change in the privilege, eliminating the need for costly remote procedure calls or change in address space. We evaluated our platform by developing a proof-of-concept LOTRx86-enabled web server that employs our architecture to securely access its private key during an SSL connection. We conducted a set of experiments including a performance measurement on the PoC on both Intel and AMD PCs, and confirmed that LOTRx86 incurs only a limited performance overhead.

History

Preferred Citation

Hojoon Lee, Chihyun Song and Brent Kang. Lord of the x86 Rings: A Portable User Mode Privilege Separation Architecture on x86. In: ACM Conference on Computer and Communications Security (CCS). 2018.

Primary Research Area

  • Threat Detection and Defenses

Name of Conference

ACM Conference on Computer and Communications Security (CCS)

Legacy Posted Date

2018-09-25

Open Access Type

  • Unknown

BibTeX

@inproceedings{cispa_all_2649, title = "Lord of the x86 Rings: A Portable User Mode Privilege Separation Architecture on x86", author = "Lee, Hojoon and Song, Chihyun and Kang, Brent Byunghoon", booktitle="{ACM Conference on Computer and Communications Security (CCS)}", year="2018", }

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