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Common Weakness Enumeration

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ID

CWE-1296: Incorrect Chaining or Granularity of Debug Components

Weakness ID: 1296
Abstraction: Base
Structure: Simple
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+ Description
The product's debug components contain incorrect chaining or granularity of debug components.
+ Extended Description

For debugging and troubleshooting a chip, several hardware design elements are often implemented, including:

  • Various Test Access Ports (TAPs) allow boundary scan commands to be executed.
  • For scanning the internal components of a chip, there are scan cells that allow the chip to be used as a "stimulus and response" mechanism.
  • Chipmakers might create custom methods to observe the internal components of their chips by placing various tracing hubs within their chip and creating hierarchical or interconnected structures among those hubs.

Logic errors during design or synthesis could misconfigure the interconnection of the debug components, which could allow unintended access permissions.

+ Relationships
Section HelpThis 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)
NatureTypeIDName
ChildOfPillarPillar - 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.284Improper Access Control
Section HelpThis 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 "Hardware Design" (CWE-1194)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1207Debug and Test Problems
+ Modes Of Introduction
Section HelpThe 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.
PhaseNote
Implementation
+ Applicable Platforms
Section HelpThis 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

Verilog (Undetermined Prevalence)

VHDL (Undetermined Prevalence)

Class: Not Language-Specific (Undetermined Prevalence)

Operating Systems

Class: Not OS-Specific (Undetermined Prevalence)

Architectures

Class: Not Architecture-Specific (Undetermined Prevalence)

Technologies

Processor Hardware (Undetermined Prevalence)

Class: Not Technology-Specific (Undetermined Prevalence)

+ Common Consequences
Section HelpThis 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.
ScopeImpactLikelihood
Confidentiality
Integrity
Access Control
Authentication
Authorization
Availability
Accountability

Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism; Execute Unauthorized Code or Commands; Modify Memory; Modify Files or Directories

Depending on the access to debug component(s) erroneously granted, an attacker could use the debug component to gain additional understanding about the system to further an attack and/or execute other commands. This could compromise any security property, including the ones listed above.
Medium
+ Demonstrative Examples

Example 1

The following example shows how an attacker can take advantage of incorrect chaining or missing granularity of debug components.

In a System-on-Chip (SoC), the user might be able to access the SoC-level TAP with a certain level of authorization. However, this access should not also grant access to all of the internal TAPs (e.g., Core). Separately, if any of the internal TAPs is also stitched to the TAP chain when it should not be because of a logic error, then an attacker can access the internal TAPs as well and execute commands there.

As a related example, suppose there is a hierarchy of TAPs (TAP_A is connected to TAP_B and TAP_C, then TAP_B is connected to TAP_D and TAP_E, then TAP_C is connected to TAP_F and TAP_G, etc.). Architecture mandates that the user have one set of credentials for just accessing TAP_A, another set of credentials for accessing TAP_B and TAP_C, etc. However, if, during implementation, the designer mistakenly implements a daisy-chained TAP where all the TAPs are connected in a single TAP chain without the hierarchical structure, the correct granularity of debug components is not implemented and the attacker can gain unauthorized access.

+ Observed Examples
ReferenceDescription
Incorrect access control in RDP Level 1 on STMicroelectronics STM32F0 series devices allows physically present attackers to extract the device's protected firmware via a special sequence of Serial Wire Debug (SWD) commands because there is a race condition between full initialization of the SWD interface and the setup of flash protection.
There is an improper authorization vulnerability in several smartphones. The system has a logic-judging error, and, under certain scenarios, a successful exploit could allow the attacker to switch to third desktop after a series of operations in ADB mode. (Vulnerability ID: HWPSIRT-2019-10114).
+ Potential Mitigations

Phase: Implementation

Ensure that debug components are properly chained and their granularity is maintained at different authentication levels.
+ Detection Methods

Architecture or Design Review

Appropriate Post-Si tests should be carried out at various authorization levels to ensure that debug components are properly chained and accessible only to users with appropriate credentials.

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

Appropriate Post-Si tests should be carried out at various authorization levels to ensure that debug components are properly chained and accessible only to users with appropriate credentials.

Effectiveness: High

+ Memberships
Section HelpThis 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.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1396Comprehensive Categorization: Access Control
+ Vulnerability Mapping Notes

Usage: Allowed

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Maintenance

This entry is still under development and will continue to see updates and content improvements.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2020-05-31
(CWE 4.2, 2020-08-20)
Arun Kanuparthi, Hareesh Khattri, Parbati Kumar MannaIntel Corporation
+ Modifications
Modification DateModifierOrganization
2021-07-20CWE Content TeamMITRE
updated Related_Attack_Patterns
2022-04-28CWE Content TeamMITRE
updated Applicable_Platforms, Related_Attack_Patterns
2022-06-28CWE Content TeamMITRE
updated Applicable_Platforms
2023-01-31CWE Content TeamMITRE
updated Related_Attack_Patterns
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
Page Last Updated: October 26, 2023