CWE-1220 Base Incompleto

Insufficient Granularity of Access Control

This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify sensitive resources. Instead of implementing precise, fine-grained…

Definición

What is CWE-1220?

This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify sensitive resources. Instead of implementing precise, fine-grained permissions, the security policy uses overly permissive rules that fail to properly restrict access to critical assets like configuration data, keys, or system registers.
In hardware and integrated circuits, access to security-sensitive assets (such as device configuration registers or encryption keys) is often managed by trusted firmware like the BIOS or bootloader. Upon startup, hardware registers default to permissive states, and this firmware is responsible for configuring proper access controls. If these controls are not granular enough—for example, protecting an entire register block instead of individual fields—unauthorized software or firmware components may gain access they shouldn't have. This lack of precision creates serious security risks. Attackers or less-privileged agents can leak sensitive data, modify secure configurations, or extract cryptographic keys. The result is a compromised device state that undermines system integrity, functionality, and overall security posture, often enabling further exploitation.
Impacto en el mundo real

Real-world CVEs caused by CWE-1220

  • CVE-2022-24985

    A form hosting website only checks the session authentication status for a single form, making it possible to bypass authentication when there are multiple forms

  • CVE-2021-36934

    An operating system has an overly permission Access Control List onsome system files, including those related to user passwords

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    Consider a system with a register for storing AES key for encryption or decryption. The key is 128 bits, implemented as a set of four 32-bit registers. The key registers are assets and registers, AES_KEY_READ_POLICY and AES_KEY_WRITE_POLICY, and are defined to provide necessary access controls. The read-policy register defines which agents can read the AES-key registers, and write-policy register defines which agents can program or write to those registers. Each register is a 32-bit register, and it can support access control for a maximum of 32 agents. The number of the bit when set (i.e., "1") allows respective action from an agent whose identity matches the number of the bit and, if "0" (i.e., Clear), disallows the respective action to that corresponding agent.

  2. 2

    In the above example, there is only one policy register that controls access to both read and write accesses to the AES-key registers, and thus the design is not granular enough to separate read and writes access for different agents. Here, agent with identities "1" and "2" can both read and write.

  3. 3

    A good design should be granular enough to provide separate access controls to separate actions. Access control for reads should be separate from writes. Below is an example of such implementation where two policy registers are defined for each of these actions. The policy is defined such that: the AES-key registers can only be read or used by a crypto agent with identity "1" when bit #1 is set. The AES-key registers can only be programmed by a trusted firmware with identity "2" when bit #2 is set.

  4. 4

    Within the AXI node interface wrapper module in the RISC-V AXI module of the HACK@DAC'19 CVA6 SoC [REF-1346], an access control mechanism is employed to regulate the access of different privileged users to peripherals.

  5. 5

    The AXI ensures that only users with appropriate privileges can access specific peripherals. For instance, a ROM module is accessible exclusively with Machine privilege, and AXI enforces that users attempting to read data from the ROM must possess machine privilege; otherwise, access to the ROM is denied. The access control information and configurations are stored in a ROM.

Ejemplo de código vulnerable

Vulnerable Other

Consider a system with a register for storing AES key for encryption or decryption. The key is 128 bits, implemented as a set of four 32-bit registers. The key registers are assets and registers, AES_KEY_READ_POLICY and AES_KEY_WRITE_POLICY, and are defined to provide necessary access controls. The read-policy register defines which agents can read the AES-key registers, and write-policy register defines which agents can program or write to those registers. Each register is a 32-bit register, and it can support access control for a maximum of 32 agents. The number of the bit when set (i.e., "1") allows respective action from an agent whose identity matches the number of the bit and, if "0" (i.e., Clear), disallows the respective action to that corresponding agent.

Vulnerable Other 
| Register | Field description | 
| --- | --- |
| AES_ENC_DEC_KEY_0 | AES key [0:31] for encryption or decryption  Default 0x00000000 |
| AES_ENC_DEC_KEY_1 | AES key [32:63] for encryption or decryption  Default 0x00000000 |
| AES_ENC_DEC_KEY_2 | AES key [64:95] for encryption or decryption  Default 0x00000000 |
| AES_ENC_DEC_KEY_4 | AES key [96:127] for encryption or decryption  Default 0x00000000 |
| AES_KEY_READ_WRITE_POLICY | [31:0] Default 0x00000006 - meaning agent with identities "1" and "2" can both read from and write to key registers  |
Ejemplo de código seguro

Secure Other

A good design should be granular enough to provide separate access controls to separate actions. Access control for reads should be separate from writes. Below is an example of such implementation where two policy registers are defined for each of these actions. The policy is defined such that: the AES-key registers can only be read or used by a crypto agent with identity "1" when bit #1 is set. The AES-key registers can only be programmed by a trusted firmware with identity "2" when bit #2 is set.

Seguro Other 
|  | 
|
| AES_KEY_READ_POLICY | [31:0] Default 0x00000002 - meaning only Crypto engine with identity "1" can read registers: AES_ENC_DEC_KEY_0, AES_ENC_DEC_KEY_1, AES_ENC_DEC_KEY_2, AES_ENC_DEC_KEY_3  |
| AES_KEY_WRITE_POLICY | [31:0] Default 0x00000004 - meaning only trusted firmware with identity "2" can program registers: AES_ENC_DEC_KEY_0, AES_ENC_DEC_KEY_1, AES_ENC_DEC_KEY_2, AES_ENC_DEC_KEY_3  |
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Lista de prevención

How to prevent CWE-1220

  • Architecture and Design / Implementation / Testing - Access-control-policy protections must be reviewed for design inconsistency and common weaknesses. - Access-control-policy definition and programming flow must be tested in pre-silicon, post-silicon testing.
Señales de detección

How to detect CWE-1220

SAST High

Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.

DAST Moderate

Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.

Runtime Moderate

Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.

Code review Moderate

Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-1220 y abre un PR de corrección en menos de 60 segundos.

Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.

Solicitar demo Probar Plexicus gratis
Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-1220?

This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify sensitive resources. Instead of implementing precise, fine-grained permissions, the security policy uses overly permissive rules that fail to properly restrict access to critical assets like configuration data, keys, or system registers.

¿Qué gravedad tiene CWE-1220?

MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.

¿Qué lenguajes o plataformas se ven afectados por CWE-1220?

MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, Not Technology-Specific.

¿Cómo puedo prevenir CWE-1220?

- Access-control-policy protections must be reviewed for design inconsistency and common weaknesses. - Access-control-policy definition and programming flow must be tested in pre-silicon, post-silicon testing.

¿Cómo detecta y corrige Plexicus CWE-1220?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-1220 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.

¿Dónde puedo aprender más sobre CWE-1220?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/1220.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-1220

CWE-284 Padre

Improper Access Control

The software fails to properly limit who can access a resource, allowing unauthorized users or systems to interact with it.

CWE-1191 Hermano

On-Chip Debug and Test Interface With Improper Access Control

This vulnerability occurs when a hardware chip's debug or test interface (like JTAG) lacks proper access controls. Without correct…

CWE-1224 Hermano

Improper Restriction of Write-Once Bit Fields

This vulnerability occurs when hardware write-once protection mechanisms, often called 'sticky bits,' are incorrectly implemented,…

CWE-1231 Hermano

Improper Prevention of Lock Bit Modification

This vulnerability occurs when hardware or firmware uses a lock bit to protect critical system registers or memory regions, but fails to…

CWE-1233 Hermano

Security-Sensitive Hardware Controls with Missing Lock Bit Protection

This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…

CWE-1252 Hermano

CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations

This vulnerability occurs when a CPU's hardware is not set up to enforce a strict separation between writing data to memory and executing…

CWE-1257 Hermano

Improper Access Control Applied to Mirrored or Aliased Memory Regions

This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to…

CWE-1259 Hermano

Improper Restriction of Security Token Assignment

This vulnerability occurs when a System-on-a-Chip (SoC) fails to properly secure its Security Token mechanism. These tokens control which…

CWE-1260 Hermano

Improper Handling of Overlap Between Protected Memory Ranges

This vulnerability occurs when a system incorrectly allows different memory protection ranges to overlap. This flaw can let attackers…

Recursos

Further reading

Listo cuando tú lo estés

Deja de pagar por desarrollador.
Empieza a cerrar el bucle.

Plexicus es el ASPM nativo de IA que escanea, filtra, corrige, pentestea y explica — de forma autónoma. Desarrolladores ilimitados, repos ilimitados, acciones de IA de uso justo. Nivel gratuito real, €269/mo anual cuando estés listo.

Comenzar gratis Reservar una demo