Missing Protection for Mirrored Regions in On-Chip Fabric Firewall
The firewall in an on-chip fabric protects the main addressed region, but it does not protect any mirrored memory or memory-mapped-IO (MMIO) regions.
Description
Few fabrics mirror memory and address ranges, where mirrored regions contain copies of the original data. This redundancy is used to achieve fault tolerance. Whatever protections the fabric firewall implements for the original region should also apply to the mirrored regions. If not, an attacker could bypass existing read/write protections by reading from/writing to the mirrored regions to leak or corrupt the original data.
Demonstrations
The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.
Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.
Example One
A memory-controller IP block is connected to the on-chip fabric in a System on Chip (SoC). The memory controller is configured to divide the memory into four parts: one original and three mirrored regions inside the memory. The upper two bits of the address indicate which region is being addressed. 00 indicates the original region and 01, 10, and 11 are used to address the mirrored regions. All four regions operate in a lock-step manner and are always synchronized. The firewall in the on-chip fabric is programmed to protect the assets in the memory.
The firewall only protects the original range but not the mirrored regions.
The attacker (as an unprivileged user) sends a write transaction to the mirrored region. The mirrored region has an address with the upper two bits set to "10" and the remaining bits of the address pointing to an asset. The firewall does not block this write transaction. Once the write is successful, contents in the protected-memory region are also updated. Thus, the attacker can bypass existing, memory protections.
Firewall should protect mirrored regions.
See Also
Weaknesses in this category are related to access control.
Weaknesses in this category are related to hardware security problems that apply to peripheral devices, IO interfaces, on-chip interconnects, network-o...
This view (slice) covers all the elements in CWE.
This view (slice) lists weaknesses that can be introduced during implementation.
This view (slice) lists weaknesses that can be introduced during design.
Common Weakness Enumeration content on this website is copyright of The MITRE Corporation unless otherwise specified. Use of the Common Weakness Enumeration and the associated references on this website are subject to the Terms of Use as specified by The MITRE Corporation.