CWE-1276 Base Incompleto

Hardware Child Block Incorrectly Connected to Parent System

This vulnerability occurs when a hardware component (IP block) is wired incorrectly to the main system, creating hidden security flaws even if basic functions appear to work.

Definición

What is CWE-1276?

This vulnerability occurs when a hardware component (IP block) is wired incorrectly to the main system, creating hidden security flaws even if basic functions appear to work.
For a system-on-chip (SoC) to operate securely, its internal hardware blocks must communicate with the parent system using the correct control and data signals. An incorrect connection—like linking a reset pin to the wrong system controller—can bypass critical security boundaries. While the device might still boot and run, this miswiring opens a backdoor that attackers can exploit to tamper with sensitive data or operations. Consider a block designed to only clear its data during a full system power cycle. If its reset line is mistakenly connected to a software-controlled debug reset, a privileged process or an attacker gaining software access could trigger an unauthorized reset. This violates the hardware's data integrity guarantees, potentially leaking secrets or corrupting secure state, all while the system seems to function normally from a user's perspective.
Impacto en el mundo real

Real-world CVEs caused by CWE-1276

Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    Many SoCs use hardware to partition system resources between trusted and un-trusted entities. One example of this concept is the Arm TrustZone, in which the processor and all security-aware IP attempt to isolate resources based on the status of a privilege bit. This privilege bit is part of the input interface in all TrustZone-aware IP. If this privilege bit is accidentally grounded or left unconnected when the IP is instantiated, privilege escalation of all input data may occur.

  2. 2

    In the Verilog code below, the security level input to the TrustZone aware peripheral is correctly driven by an appropriate signal instead of being grounded.

  3. 3

    Here is a code snippet from the Ariane core module in the HACK@DAC'21 Openpiton SoC [REF-1362]. To ensure full functional correctness, developers connect the ports with names. However, in some cases developers forget to connect some of these ports to the desired signals in the parent module. These mistakes by developers can lead to incorrect functional behavior or, in some cases, introduce security vulnerabilities.

  4. 4

    In the above example from HACK@DAC'21, since interrupt signals are not properly connected, the CSR module will fail to send notifications in the event of interrupts. Consequently, critical information in CSR registers that should be flushed or modified in response to an interrupt won't be updated. These vulnerabilities can potentially result in information leakage across various privilege levels.

  5. 5

    To address the aforementioned vulnerability, developers must follow a two-step approach. First, they should ensure that all module signals are properly connected. This can often be facilitated using automated tools, and many simulators and sanitizer tools issue warnings when a signal remains unconnected or floats. Second, it is imperative to validate that the signals connected to a module align with the specifications. In the provided example, the developer should establish the correct connection of interrupt signals from the parent module (Ariane core) to the child module (csr_regfile) [REF-1363].

Ejemplo de código vulnerable

Vulnerable Verilog

Many SoCs use hardware to partition system resources between trusted and un-trusted entities. One example of this concept is the Arm TrustZone, in which the processor and all security-aware IP attempt to isolate resources based on the status of a privilege bit. This privilege bit is part of the input interface in all TrustZone-aware IP. If this privilege bit is accidentally grounded or left unconnected when the IP is instantiated, privilege escalation of all input data may occur.

Vulnerable Verilog 
// IP definition
 module tz_peripheral(clk, reset, data_in, data_in_security_level, ...);

```
   input clk, reset;
   input [31:0] data_in;
   input data_in_security_level;
   ...
 endmodule
 // Instantiation of IP in a parent system
 module soc(...)
   ...
   tz_peripheral u_tz_peripheral(
  	 .clk(clk),
  	 .rst(rst),
  	 .data_in(rdata),
  	 //Copy-and-paste error or typo grounds data_in_security_level (in this example 0=secure, 1=non-secure) effectively promoting all data to "secure")
  	 .data_in_security_level(1'b0),
   );
   ...
 endmodule
Ejemplo de código seguro

Secure Verilog

In the Verilog code below, the security level input to the TrustZone aware peripheral is correctly driven by an appropriate signal instead of being grounded.

Seguro Verilog 
// Instantiation of IP in a parent system
 module soc(...)

```
   ...
   tz_peripheral u_tz_peripheral(
  	 .clk(clk),
  	 .rst(rst),
  	 .data_in(rdata),
  	 // This port is no longer grounded, but instead driven by the appropriate signal
  	 .data_in_security_level(rdata_security_level),
   );
   ...
 endmodule
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-1276

  • Testing System-level verification may be used to ensure that components are correctly connected and that design security requirements are not violated due to interactions between various IP blocks.
Señales de detección

How to detect CWE-1276

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-1276 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.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-1276?

This vulnerability occurs when a hardware component (IP block) is wired incorrectly to the main system, creating hidden security flaws even if basic functions appear to work.

¿Qué gravedad tiene CWE-1276?

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-1276?

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

¿Cómo puedo prevenir CWE-1276?

System-level verification may be used to ensure that components are correctly connected and that design security requirements are not violated due to interactions between various IP blocks.

¿Cómo detecta y corrige Plexicus CWE-1276?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-1276 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-1276?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/1276.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-1276

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CWE-1191 Hermano

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CWE-1220 Hermano

Insufficient Granularity of Access Control

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CWE-1224 Hermano

Improper Restriction of Write-Once Bit Fields

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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

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CWE-1252 Hermano

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

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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…

Recursos

Further reading

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