CWE-1299 Base Draft

Missing Protection Mechanism for Alternate Hardware Interface

This vulnerability occurs when a hardware component's security controls only protect the primary access path, leaving alternate interfaces unprotected. Attackers can bypass intended restrictions by…

Definition

What is CWE-1299?

This vulnerability occurs when a hardware component's security controls only protect the primary access path, leaving alternate interfaces unprotected. Attackers can bypass intended restrictions by accessing sensitive assets through these unguarded backdoors, such as shadow registers or other external-facing ports.
Modern chips and Systems-on-Chip (SoCs) often contain multiple access paths to critical internal registers—through interfaces like PCIe, USB, UART, or SMBus. If access controls are only enforced on one primary interface (e.g., PCIe), an attacker can simply route malicious transactions through an alternate, unprotected interface (like UART or USB) to modify or read protected registers, completely bypassing the intended security layer. Another common bypass involves shadow or mirror registers, which are duplicate registers that temporarily hold data before syncing with a main register. These are often implemented for performance or debugging purposes. If these shadow registers lack the same access protections as their primary counterparts, attackers can directly target them to alter system state, compromise security configurations, or leak sensitive information, effectively undermining the chip's entire protection scheme.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-1299

  • CVE-2022-38399

    Missing protection mechanism on serial connection allows for arbitrary OS command execution.

  • CVE-2020-9285

    Mini-PCI Express slot does not restrict direct memory access.

  • CVE-2020-8004

    When the internal flash is protected by blocking access on the Data Bus (DBUS), it can still be indirectly accessed through the Instruction Bus (IBUS).

  • CVE-2017-18293

    When GPIO is protected by blocking access to corresponding GPIO resource registers, protection can be bypassed by writing to the corresponding banked GPIO registers instead.

  • CVE-2020-15483

    monitor device allows access to physical UART debug port without authentication

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.

  2. 2

    Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.

  3. 3

    Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.

  4. 4

    Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.

Verwundbares Codebeispiel

Vulnerable Verilog

Verwundbar Verilog 
assign addr_auth = (address == 32'hF00) ? 1: 0;
Sicheres Codebeispiel

Secure Verilog

The bugged line of code is repeated in the Bad example above. The weakness arises from the fact that the SECURE_ME register can be modified by writing to the shadow register COPY_OF_SECURE_ME. The address of COPY_OF_SECURE_ME should also be included in the check. That buggy line of code should instead be replaced as shown in the Good Code Snippet below.

Sicher Verilog 
assign addr_auth = (address == 32'hF00 || address == 32'h800F00) ? 1: 0;
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-1299

  • Requirements Protect assets from accesses against all potential interfaces and alternate paths.
  • Architecture and Design Protect assets from accesses against all potential interfaces and alternate paths.
  • Implementation Protect assets from accesses against all potential interfaces and alternate paths.
Erkennungssignale

How to detect CWE-1299

SAST High

Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.

DAST Moderate

Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.

Runtime Moderate

Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.

Code review Moderate

Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.

Plexicus Auto-Fix

Plexicus erkennt CWE-1299 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen
Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-1299?

This vulnerability occurs when a hardware component's security controls only protect the primary access path, leaving alternate interfaces unprotected. Attackers can bypass intended restrictions by accessing sensitive assets through these unguarded backdoors, such as shadow registers or other external-facing ports.

Wie gravierend ist CWE-1299?

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-1299 betroffen?

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

Wie kann ich CWE-1299 verhindern?

Protect assets from accesses against all potential interfaces and alternate paths. Protect assets from accesses against all potential interfaces and alternate paths.

Wie erkennt und behebt Plexicus CWE-1299?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-1299 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-1299?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/1299.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-1299

CWE-420 Parent

Unprotected Alternate Channel

This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker…

CWE-421 Sibling

Race Condition During Access to Alternate Channel

A race condition occurs when an application opens a secondary communication channel intended for an authorized user, but fails to secure…

CWE-422 Sibling

Unprotected Windows Messaging Channel ('Shatter')

This vulnerability, often called a 'Shatter' attack, occurs when a Windows application running with high privileges accepts messages from…

CWE-1191 Peer

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…

Ressourcen

Further reading

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