CWE-1243: Exposure of Security-Sensitive Fuse Values During Debug
Several security-sensitive values are blown as fuses in a chip to be used during early-boot flows or later at runtime. Examples of these security-sensitive values include root keys, encryption keys, manufacturing-specific information, chip-manufacturer-specific information, and original-equipment-manufacturer (OEM) data. After the chip is powered on, these values are sensed from fuses and stored in temporary locations such as registers and local memories. These locations are typically access-control protected from untrusted agents capable of accessing them. Even to trusted agents, only read-access is provided. However, these locations are not blocked during debug flows, allowing an untrusted debugger to access these assets and compromise system security.
The table(s) below 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)
Relevant to the view "Hardware Design" (CWE-1194)
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.
The listings below show 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.
Class: Language-Independent (Undetermined Prevalence)
Class: OS-Independent (Undetermined Prevalence)
Class: Architecture-Independent (Undetermined Prevalence)
Class: System on Chip (Undetermined Prevalence)
The table below 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.
Secret manufacturing data (such as die information) are stored in fuses. While the chip powers on, this value is sensed from fuses and is stored in a microarchitectural register. This register is only given read access to trusted software running on the core. Untrusted software running on the core cannot access it.
Example Language: Other
All microarchitectural registers in this chip can be accessed through the debug interface. As a result, even an untrusted debugger can access this data and get hold of secret manufacturing data.
Registers used to store security-sensitive values sensed from fuses should be blocked on debug. They should be disconnected from the debug interface.
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