Exploit Methods/Userspace execution

Details

Once an attacker has gain control over the instruction pointers, it must be aimed somewhere. The place where attackers have the most control over memory layout tends to be in userspace, so it has been natural to place malicious code in userspace and have the kernel redirection execution there.

For more details, see Userspace access, as that is technically a superset of userspace execution.

Examples

• See nearly every other exploit example listed under other Exploit Methods and Bug Classes.

Mitigations

• hardware segmentation: SMEP (x86), PXN (arm)
• compiler instrumentation to set high bit on function calls
• emulate memory segmentation via separate page tables (e.g. PAX_MEMORY_UDEREF)