CWE-1222: Insufficient Granularity of Address Regions Protected by Register Locks

VariantIncomplete

The product defines a large address region protected from modification by the same register lock control bit. This results in a conflict between the functional requirement that some addresses need to be writable by software during operation and the security requirement that the system configuration lock bit must be set during the boot process.

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Extended Description

Integrated circuits and hardware IPs can expose the device configuration controls that need to be programmed after device power reset by a trusted firmware or software module (commonly set by BIOS/bootloader) and then locked from any further modification. In hardware design, this is commonly implemented using a programmable lock bit which enables/disables writing to a protected set of registers or address regions. When the programmable lock bit is set, the relevant address region can be implemented as a hardcoded value in hardware logic that cannot be changed later. A problem can arise wherein the protected region definition is not granular enough. After the programmable lock bit has been set, then this new functionality cannot be implemented without change to the hardware design.

Code Examples & CVEs

Demonstrative Examples

For example, consider a hardware unit with a 32 kilobyte configuration address space where the first 8 kilobyte address contains security sensitive controls that must only be writable by device bootloader. One way to protect the security configuration could be to define a 32 bit system configuration locking register (SYS_LOCK) where each bit lock locks the corresponding 1 kilobyte region.

If a register exists within the first kilobyte address range (e.g. SW_MODE, address 0x310) and needs to be software writable at runtime, then this register cannot be written in a securely configured system since SYS_LOCK register lock bit 0 must be set to protect other security settings (e.g. SECURITY_FEATURE_ENABLE, address 0x0004). The only fix would be to change the hardware logic or not set the security lock bit.

BadOther

Address                                     Register                                                                                                       0x0000                                     SYS_LOCK: 32 bit system configuration lock register, each bit is write-1-once                                                                                                       0x0004                                     SECURITY_FEATURE_ENABLE: 32 bit register controlling enabling of security features                                                                                                       ...                                                                                                                                            0x0310                                     SW_MODE: 32 bit Software Mode indication register                                                                                                                                                                                                                    Address region                                     Lock bit                                                                                                       0x0000 - 0x03FF                                     SYS_LOCK[0]                                                                                                       0x0400 - 0x07FF                                     SYS_LOCK[1]                                                                                                       ...                                                                                                                                            0x7C00 - 0x7FFF                                     SYS_LOCK[31]

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-1222 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-1222, Insufficient Granularity of Address Regions Protected by Register Locks, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Insufficient Granularity of Address Regions Protected by Register Locks during Architecture and Design

MITRE associates mitigation with Architecture and Design; recorded impacts include Other; the entry maps to CAPEC-679. Use these source-defined anchors to turn CWE-1222 into implementation, review, and verification checks for the affected component.

CWE-1222: Insufficient Granularity of Address Regions Protected by Register Locks — MITRE CWE

Triage CWE-1222 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-1222, Insufficient Granularity of Address Regions Protected by Register Locks, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-1222

Apply MITRE's full root-cause mapping guidance when using CWE-1222, Insufficient Granularity of Address Regions Protected by Register Locks. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-1222 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-1222, Insufficient Granularity of Address Regions Protected by Register Locks. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-1222: Insufficient Granularity of Address Regions Protected by Register Locks?+

CWE-1222: Insufficient Granularity of Address Regions Protected by Register Locks is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product defines a large address region protected from modification by the same register lock control bit. This results in a conflict between the functional requirement that some addresses need to be writable by software during operation and the security requirement that the system configuration lock bit must be set during the boot process. Integrated circuits and hardware IPs can expose the device configuration controls that need to be programmed after device power reset by a trusted firmware or software module (commonly set by BIOS/bootloader) and then locked from any further modification. In hardware design, this is commonly implemented using a programmable lock bit which enables/disables writing to a protected set of registers or address regions. When the programmable lock bit is set, the relevant address region can be implemented as a hardcoded value in hardware logic that cannot be changed later. A problem can arise wherein the protected region definition is not granular enough. After the programmable lock bit has been set, then this new functionality cannot be implemented without change to the hardware design.

What are the security consequences of Insufficient Granularity of Address Regions Protected by Register Locks?+

If exploited, CWE-1222 (Insufficient Granularity of Address Regions Protected by Register Locks) it can compromise Access Control, leading to outcomes such as Other.

How do you prevent or mitigate Insufficient Granularity of Address Regions Protected by Register Locks?+

Recommended mitigations for CWE-1222 include: The defining of protected locked registers should be reviewed or tested early in the design phase with software teams to ensure software flows are not blocked by the security locks. As an alternative to using register lock control bits and fixed access control regions, the hardware design could use programmable security access control configuration so that device trusted firmware can configure and change the protected regions based on software usage and security models.

Which programming languages are affected by Insufficient Granularity of Address Regions Protected by Register Locks?+

CWE-1222 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-1222 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-1222: Insufficient Granularity of Address Regions Protected by Register Locks

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