CWE - CWE-1316: Fabric-Address Map Allows Programming of Unwarranted Overlaps of Protected and Unprotected Ranges (4.11)

Weakness ID: 1316

Abstraction: Base
Structure: Simple

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Description

The address map of the on-chip fabric has protected and unprotected regions overlapping, allowing an attacker to bypass access control to the overlapping portion of the protected region.

Extended Description

Various ranges can be defined in the system-address map, either in the memory or in Memory-Mapped-IO (MMIO) space. These ranges are usually defined using special range registers that contain information, such as base address and size. Address decoding is the process of determining for which range the incoming transaction is destined. To ensure isolation, ranges containing secret data are access-control protected.

Occasionally, these ranges could overlap. The overlap could either be intentional (e.g. due to a limited number of range registers or limited choice in choosing size of the range) or unintentional (e.g. introduced by errors). Some hardware designs allow dynamic remapping of address ranges assigned to peripheral MMIO ranges. In such designs, intentional address overlaps can be created through misconfiguration by malicious software. When protected and unprotected ranges overlap, an attacker could send a transaction and potentially compromise the protections in place, violating the principle of least privilege.

Relationships

This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

Relevant to the view "Research Concepts" (CWE-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	284	Improper Access Control

Relevant to the view "Hardware Design" (CWE-1194)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1203	Peripherals, On-chip Fabric, and Interface/IO Problems

Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Phase	Note
Architecture and Design
Implementation

Applicable Platforms

This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Operating Systems

Class: Not OS-Specific (Undetermined Prevalence)

Architectures

Class: Not Architecture-Specific (Undetermined Prevalence)

Technologies

Bus/Interface Hardware (Undetermined Prevalence)

Class: Not Technology-Specific (Undetermined Prevalence)

Common Consequences

This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Scope	Impact	Likelihood
Confidentiality Integrity Access Control Authorization	Technical Impact: Bypass Protection Mechanism; Read Memory; Modify Memory	Medium

Demonstrative Examples

Example 1

An on-chip fabric supports a 64KB address space that is memory-mapped. The fabric has two range registers that support creation of two protected ranges with specific size constraints--4KB, 8KB, 16KB or 32KB. Assets that belong to user A require 4KB, and those of user B require 20KB. Registers and other assets that are not security-sensitive require 40KB. One range register is configured to program 4KB to protect user A's assets. Since a 20KB range cannot be created with the given size constraints, the range register for user B's assets is configured as 32KB. The rest of the address space is left as open. As a result, some part of untrusted and open-address space overlaps with user B range.

The fabric does not support least privilege, and an attacker can send a transaction to the overlapping region to tamper with user B data.

Since range B only requires 20KB but is allotted 32KB, there is 12KB of reserved space. Overlapping this region of user B data, where there are no assets, with the untrusted space will prevent an attacker from tampering with user B data.

Observed Examples

Reference	Description
CVE-2009-4419	Attacker can modify MCHBAR register to overlap with an attacker-controlled region, which modification prevents the SENTER instruction from properly applying VT-d protection while a Measured Launch Environment is being launched.

Potential Mitigations

Phase: Architecture and Design

When architecting the address map of the chip, ensure that protected and unprotected ranges are isolated and do not overlap. When designing, ensure that ranges hardcoded in Register-Transfer Level (RTL) do not overlap.

Phase: Implementation

Ranges configured by firmware should not overlap. If overlaps are mandatory because of constraints such as a limited number of registers, then ensure that no assets are present in the overlapped portion.

Phase: Testing

Validate mitigation actions with robust testing.

Detection Methods

Automated Dynamic Analysis

Review address map in specification to see if there are any overlapping ranges.

Effectiveness: High

Manual Static Analysis

Negative testing of access control on overlapped ranges.

Effectiveness: High

Memberships

This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1396	Comprehensive Categorization: Access Control

Notes

Maintenance

As of CWE 4.6, CWE-1260 and CWE-1316 are siblings under view 1000, but CWE-1260 might be a parent of CWE-1316. More analysis is warranted.

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-456	Infected Memory
CAPEC-679	Exploitation of Improperly Configured or Implemented Memory Protections

References

[REF-1137] Yuriy Bulygin, Oleksandr Bazhaniuk, Andrew Furtak, John Loucaides, Mikhail Gorobets. "BARing the System - New vulnerabilities in Coreboot & UEFI-based Systems". 2017. <https://www.c7zero.info/stuff/REConBrussels2017_BARing_the_system.pdf>.

Content History

Submissions
Submission Date	Submitter	Organization
2020-06-01	Arun Kanuparthi, Hareesh Khattri, Parbati Kumar Manna	Intel Corporation
2020-06-01
Modifications
Modification Date	Modifier	Organization
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Maintenance_Notes
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Applicable_Platforms, Related_Attack_Patterns
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Applicable_Platforms
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Related_Attack_Patterns
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships


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Common Weakness Enumeration

CWE-1316: Fabric-Address Map Allows Programming of Unwarranted Overlaps of Protected and Unprotected Ranges

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