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Application & OT Security · Advanced

Pointer Authentication (PAC)

An ARM architecture feature that signs pointers such as return addresses with a cryptographic code and verifies them before use.

Definition

Pointer Authentication Codes are stored in unused upper bits of 64-bit pointers. Corrupting a signed pointer causes authentication failure, mitigating ROP and other control-flow hijacking. Apple silicon and recent Android devices use it.

Example

Return addresses are signed on function entry and authenticated before return on PAC-enabled ARM64 devices.

Exam tip

Hardware exploit mitigation comparable in purpose to shadow stacks.

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