CWE-1243 Base Incomplet

Sensitive Non-Volatile Information Not Protected During Debug

This vulnerability occurs when security-critical data stored in hardware fuses is left unprotected and accessible during debug modes.

Définition

What is CWE-1243?

This vulnerability occurs when security-critical data stored in hardware fuses is left unprotected and accessible during debug modes.
Modern chips store highly sensitive data—like encryption keys, root secrets, and unique manufacturer codes—in permanent hardware fuses. When the device powers on, this information is loaded into temporary registers or on-chip memory for runtime use. While normal software access to these locations is usually restricted, debug interfaces often bypass these protections entirely. During debug or testing operations, these temporary storage locations remain exposed, allowing anyone with debug access to read the sensitive fuse data. This creates a significant hardware-level security gap, as an attacker can extract foundational secrets that underpin the device's entire security model, potentially compromising encryption, authentication, and secure boot processes.
Impact réel

Real-world CVEs caused by CWE-1243

Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    Sensitive manufacturing data (such as die information) are stored in fuses. When the chip powers on, these values are read from the fuses and stored in microarchitectural registers. These registers are only given read access to trusted software running on the core. Untrusted software running on the core is not allowed to access these registers.

  2. 2

    The example code below is taken from one of the AES cryptographic accelerators of the HACK@DAC'21 buggy OpenPiton SoC [REF-1366]. The operating system (OS) uses three AES keys to encrypt and decrypt sensitive data using this accelerator. These keys are sensitive data stored in fuses. The security of the OS will be compromised if any of these AES keys are leaked. During system bootup, these AES keys are sensed from fuses and stored in temporary hardware registers of the AES peripheral. Access to these temporary registers is disconnected during the debug state to prevent them from leaking through debug access. In this example (see the vulnerable code source), the registers key0, key1, and key2 are used to store the three AES keys (which are accessed through key_big0, key_big1, and key_big2 signals). The OS selects one of these three keys through the key_big signal, which is used by the AES engine.

  3. 3

    The above code illustrates an instance of a vulnerable implementation for blocking AES key mechanism when the system is in debug mode (i.e., when debug_mode_i is asserted). During debug mode, key accesses through key_big0 and key_big1 are effectively disconnected, as their values are set to zero. However, the key accessed via the key_big2 signal remains accessible, creating a potential pathway for sensitive fuse data leakage, specifically AES key2, during debug mode. Furthermore, even though it is not strictly necessary to disconnect the key_big signal when entering debug mode (since disconnecting key_big0, key_big1, and key_big2 will inherently disconnect key_big), it is advisable, in line with the defense-in-depth strategy, to also sever the connection to key_big. This additional security measure adds an extra layer of protection and safeguards the AES keys against potential future modifications to the key_big logic.

  4. 4

    To mitigate this, disconnect access through key_big2 and key_big during debug mode [REF-1367].

Exemple de code vulnérable

Vulnerable Other

Sensitive manufacturing data (such as die information) are stored in fuses. When the chip powers on, these values are read from the fuses and stored in microarchitectural registers. These registers are only given read access to trusted software running on the core. Untrusted software running on the core is not allowed to access these registers.

Vulnérable Other 
All microarchitectural registers in this chip can be accessed through the debug interface. As a result, even an untrusted debugger can access this data and retrieve sensitive manufacturing data.
Exemple de code sécurisé

Secure Other

Sécurisé Other 
Registers used to store sensitive values read from fuses should be blocked during debug. These registers should be disconnected from the debug interface.
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-1243

  • Architecture and Design / Implementation Disable access to security-sensitive information stored in fuses directly and also reflected from temporary storage locations when in debug mode.
Signaux de détection

How to detect CWE-1243

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-1243 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-1243 ?

This vulnerability occurs when security-critical data stored in hardware fuses is left unprotected and accessible during debug modes.

Quelle est la gravité de CWE-1243 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-1243 ?

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

Comment puis-je prévenir CWE-1243 ?

Disable access to security-sensitive information stored in fuses directly and also reflected from temporary storage locations when in debug mode.

Comment Plexicus détecte et corrige CWE-1243 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-1243 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-1243 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/1243.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-1243

CWE-1263 Parent

Improper Physical Access Control

This vulnerability occurs when a device or system has areas meant to be physically secure, but the safeguards in place are too weak to…

Ressources

Further reading

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