CWE-1318 Base Incomplete

Missing Support for Security Features in On-chip Fabrics or Buses

This vulnerability occurs when the communication channels (fabrics or buses) within a chip lack built-in or enabled security features, such as privilege separation or access controls, leaving data…

Definition

What is CWE-1318?

This vulnerability occurs when the communication channels (fabrics or buses) within a chip lack built-in or enabled security features, such as privilege separation or access controls, leaving data transfers unprotected.

Many on-chip communication systems, especially simpler or low-power designs, are built solely for moving data and lack interfaces to carry critical security attributes like privilege levels or device identity from a master component (like a CPU) to a slave (like a peripheral). Without these dedicated signals, the fabric cannot enforce security policies, making it unsafe for transporting any sensitive security metadata. Even when a bus specification includes optional security signaling, these features are often left unconnected or disabled when the hardware design is generated. Consequently, any peripheral that handles security-sensitive assets should not be connected directly to such a bus unless robust access control is implemented at an earlier point, such as a bridge or intermediary module, before transactions enter the insecure fabric.

Auswirkungen in der Praxis

Real-world CVEs caused by CWE-1318

Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.

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Angreiferpfad Schritt für Schritt

1
Several systems on chips (SoCs) use the Advanced-Microcontroller Bus Architecture (AMBA) Advanced-Peripheral Bus (APB) protocol. APB is a simple, low-power bus and uses the PPROT[2:0] bits to indicate the security state of the bus masters ;PPROT[0] indicates privilege, PPROT[1] indicates secure/non-secure transaction, and PPROT[2] indicates instruction/data. Assume that there is no fabric bridge in the SoC. One of the slaves, the power-management unit, contains registers that store the thermal-shutdown limits.
2
The APB bus is used to connect several bus masters, each with a unique and immutable hardware identity, to several slaves. For a CPU supporting 8 potential identities (each with varying privilege levels), 16 types of outgoing transactions can be made--8 read transactions with each supported privilege level and 8 write transactions with each supported privilege level.
3
Since APB PPROT can only support up to 8 transaction types, access-control checks cannot be performed on transactions going to the slaves at the right granularity for all possible transaction types. Thus, potentially, user code running on the CPU could maliciously corrupt the thermal-shutdown-configuration registers to burn the device, resulting in permanent denial of service.
4
In this scenario, only peripherals that need access protection from 8 of the 16 possible transaction types can be connected to the APB bus. Peripherals that require protection from the remaining 8 transaction types can be connected to a different APB bus. Alternatively, a bridge could be implemented to handle such complex scenarios before forwarding traffic to the APB bus.
5
The Open-Core-Protocol (OCP) fabric supports two configurable, width-optional signals for transporting security attributes: MReqInfo and SRespInfo. MReqInfo is used to transport security attributes from bus master to slave, and SRespInfo is used to transport security attributes from slave to bus master. An SoC uses OCP to connect several bus masters, each with a unique and immutable hardware identity, to several slaves. One of the bus masters, the CPU, reports the privilege level (user or super user) in addition to the unique identity. One of the slaves, the power-management unit, contains registers that store the thermal-shutdown limits.

Verwundbares Codebeispiel

Vulnerable pseudo

MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.

Verwundbar pseudo

// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}

Sicheres Codebeispiel

Secure pseudo

Sicher pseudo

// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}

What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.

Präventions-Checkliste

How to prevent CWE-1318

Architecture and Design If fabric does not support security features, implement security checks in a bridge or any component that is between the master and the fabric. Alternatively, connect all fabric slaves that do not have any security assets under one such fabric and connect peripherals with security assets to a different fabric that supports security features.

Erkennungssignale

How to detect CWE-1318

Architecture or Design Review High

Review the fabric specification and ensure that it contains signals to transfer security-sensitive signals.

Manual Static Analysis - Source Code High

Lack of security features can also be confirmed through manual RTL review of the fabric RTL.

CWE-1318

Don't catalog this weakness. Prove it's reachable.

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Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-1318?

Wie gravierend ist CWE-1318?

MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.

Welche Sprachen oder Plattformen sind von CWE-1318 betroffen?

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

Wie kann ich CWE-1318 verhindern?

If fabric does not support security features, implement security checks in a bridge or any component that is between the master and the fabric. Alternatively, connect all fabric slaves that do not have any security assets under one such fabric and connect peripherals with security assets to a different fabric that supports security features.

Wie erkennt und behebt Plexicus CWE-1318?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-1318 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-1318?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/1318.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-1318

CWE-693 Parent

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Missing Support for Security Features in On-chip Fabrics or Buses

What is CWE-1318?

Real-world CVEs caused by CWE-1318

Angreiferpfad Schritt für Schritt

Vulnerable pseudo

Secure pseudo

How to prevent CWE-1318

How to detect CWE-1318

Don't catalog this weakness. Prove it's reachable.

Frequently asked questions

Weaknesses related to CWE-1318

Protection Mechanism Failure

Inadequate Detection or Handling of Adversarial Input Perturbations in Automated Recognition Mechanism

Semiconductor Defects in Hardware Logic with Security-Sensitive Implications

Incorrect Selection of Fuse Values

Product Released in Non-Release Configuration

Missing Protection Against Hardware Reverse Engineering Using Integrated Circuit (IC) Imaging Techniques

Public Key Re-Use for Signing both Debug and Production Code

Improper Protection against Electromagnetic Fault Injection (EM-FI)

Missing Immutable Root of Trust in Hardware

Further reading

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Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`