2008
Extended Description
In integrated circuits and hardware intellectual property (IP) cores, device configuration controls are
commonly programmed after a device power reset by a trusted firmware or software module (e.g.,
BIOS/bootloader) and then locked from any further modification.
This behavior is commonly implemented using a trusted lock bit. When set, the lock bit
disables writes to a protected set of registers or address regions. Design or coding errors in the
implementation of the lock bit protection feature may allow the lock bit to be modified or cleared by
software after it has been set. Attackers might be able to unlock the system and features that the
bit is intended to protect.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOr 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 may want to be explored.
Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name Page
ChildOf 284 Improper Access Control 680
Weakness Ordinalities
Primary :
Applicable Platforms
Language : Not Language-Specific (Prevalence = Undetermined)
Operating_System : Not OS-Specific (Prevalence = Undetermined)
Architecture : Not Architecture-Specific (Prevalence = Undetermined)
Technology : Not Technology-Specific (Prevalence = Undetermined)
Common Consequences
Scope Impact Likelihood
Access Control Modify Memory
Registers protected by lock bit can be modified even when
lock is set.
High
Detection Methods
Manual Analysis
Set the lock bit. Power cycle the device. Attempt to clear the lock bit. If the information is
changed, implement a design fix. Retest. Also, attempt to indirectly clear the lock bit or bypass it.
Effectiveness = High
Potential Mitigations
Phase: Architecture and Design
Phase: Implementation
Phase: Testing
Security lock bit protections must be reviewed for design inconsistency and common
weaknesses. Security lock programming flow and lock properties must be tested in pre-silicon
and post-silicon testing.
Effectiveness = High
CWE Version 4.14
CWE-1231: Improper Prevention of Lock Bit Modification
CWE-1231: Improper Prevention of Lock Bit Modification