CWE-1257 Improper Access Control Applied to Mirrored or Aliased Memory Regions

Aliased or mirrored memory regions in hardware designs may have inconsistent read/write permissions enforced by the hardware.

A common security weakness that can exist in such memory mapping is that aliased memory regions could have different read/write access protections enforced by the hardware such that an untrusted agent is blocked from accessing a memory address but is not blocked from accessing the corresponding aliased memory address. Such inconsistency can then be used to bypass the access protection of the primary memory block and read or modify the protected memory. An untrusted agent could also possibly create memory aliases in the system address map for malicious purposes if it is able to change the mapping of an address region or modify memory region sizes.

• Confidentiality: Read Memory — An untrusted agent might be blocked from accessing a memory region, but it is not blocked from accessing the corresponding aliased memory region. • Integrity: Modify Memory — An untrusted agent might be blocked from accessing a memory region, but it is not blocked from accessing the corresponding aliased memory region. • Availability: DoS: Instability

• [Architecture and Design, Implementation] The checks should be applied for consistency access rights between primary memory regions and any mirrored or aliased memory regions. If different memory protection units (MPU) are protecting the aliased regions, their protected range definitions and policies should be synchronized. • [Architecture and Design, Implementation] The controls that allow enabling memory aliases or changing the size of mapped memory regions should only be programmable by trusted software components.