The device includes chicken bits or undocumented features that can create entry points for unauthorized actors.
A common design practice is to use undocumented bits on a device that can be used to disable certain functional security features. These bits are commonly referred to as "chicken bits". They can facilitate quick identification and isolation of faulty components, features that negatively affect performance, or features that do not provide the required controllability for debug and test. Another way to achieve this is through implementation of undocumented features. An attacker might exploit these interfaces for unauthorized access.
| Nature | Mapping | Type | ID | Name |
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| Nature | Mapping | Type | ID | Name |
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| Nature | Mapping | Type | ID | Name |
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| Scope | Likelihood | Impact | Note |
|---|---|---|---|
| ConfidentialityIntegrityAvailabilityAccess Control | N/A | Modify MemoryRead MemoryExecute Unauthorized Code or CommandsGain Privileges or Assume IdentityBypass Protection Mechanism | N/A |
The implementation of chicken bits in a released product is highly discouraged. If implemented at all, ensure that they are disabled in production devices. All interfaces to a device should be documented.
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Consider a device that comes with various security measures, such as secure boot. The secure-boot process performs firmware-integrity verification at boot time, and this code is stored in a separate SPI-flash device. However, this code contains undocumented "special access features" intended to be used only for performing failure analysis and intended to only be unlocked by the device designer.
Remove all chicken bits and hidden features that are exposed to attackers. Add authorization schemes that rely on cryptographic primitives to access any features that the manufacturer does not want to expose. Clearly document all interfaces.
| Reference | Description |
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| Ordinality | Description |
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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.
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.
| Taxonomy Name | Entry ID | Fit | Entry Name |
|---|---|---|---|
| ISA/IEC 62443 | Part 4-1 | N/A | Req SD-4 |
| ISA/IEC 62443 | Part 4-1 | N/A | Req SVV-3 |
| ISA/IEC 62443 | Part 4-2 | N/A | Req CR 2.12 |