CWE-1223 Base Incomplete

Race Condition for Write-Once Attributes

This vulnerability occurs when an untrusted software component wins a race condition and writes to a hardware register before the trusted component can, permanently locking in an insecure value…

Definition

What is CWE-1223?

This vulnerability occurs when an untrusted software component wins a race condition and writes to a hardware register before the trusted component can, permanently locking in an insecure value because the register is designed to be written only once.

In hardware design, critical security settings are often stored in write-once registers. These registers allow software to set a value—like a system configuration or a security policy—a single time after a reset, after which they become read-only. This mechanism is intended to let trusted boot firmware establish a secure baseline that untrusted runtime software cannot later alter. A security flaw emerges when the hardware design does not properly sequence access to these registers. If an untrusted software module (Module B) can issue a write command before the trusted module (Module A) does, the untrusted value gets permanently locked in. The trusted module's subsequent write is ignored, leaving the system configured with potentially insecure or incorrect settings for its entire operational lifetime.

Auswirkungen in der Praxis

Real-world CVEs caused by CWE-1223

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

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

1
Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.
2
Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.
3
Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.
4
Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.

Verwundbares Codebeispiel

Vulnerable Verilog

consider the example design module system verilog code shown below. register_write_once_example module is an example of register that has a write-once field defined. Bit 0 field captures the write_once_status value.

Verwundbar Verilog

module register_write_once_example
 (

```
   input [15:0] Data_in,
   input Clk,
   input ip_resetn,
   input global_resetn,
   input write,
   output reg [15:0] Data_out
 );
 reg Write_once_status;
 always @(posedge Clk or negedge ip_resetn)
 if (~ip_resetn)
   begin
  	 Data_out <= 16'h0000; 
  	 Write_once_status <= 1'b0;
   end
 else if (write & ~Write_once_status) 
   begin
  	 Data_out <= Data_in & 16'hFFFE; // Input data written to register after masking bit 0
  	 Write_once_status <= 1'b1; // Write once status set after first write.
   end
 else if (~write)
   begin
  	 Data_out[15:1] <= Data_out[15:1];
  	 Data_out[0] <= Write_once_status;
   end
 endmodule

Sicheres Codebeispiel

Secure Other

The first system component that sends a write cycle to this register can program the value. This could result in a race condition security issue in the SoC design, if an untrusted agent is running in the system in parallel with the trusted component that is expected to program the register.

Sicher Other

Trusted firmware or software trying to set the write-once field: 

  - Must confirm the Write_once_status (bit 0) value is zero, before programming register. If another agent has programmed the register before, then Write_once_status value will be one.

  - After writing to the register, the trusted software can issue a read to confirm that the valid setting has been programmed.

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-1223

Architecture and Design During hardware design all register write-once or sticky fields must be evaluated for proper configuration.
Testing The testing phase should use automated tools to test that values are not reprogrammable and that write-once fields lock on writing zeros.

Erkennungssignale

How to detect CWE-1223

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-1223 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-1223?

Wie gravierend ist CWE-1223?

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-1223 betroffen?

MITRE lists the following affected platforms: Verilog, VHDL, System on Chip.

Wie kann ich CWE-1223 verhindern?

During hardware design all register write-once or sticky fields must be evaluated for proper configuration. The testing phase should use automated tools to test that values are not reprogrammable and that write-once fields lock on writing zeros.

Wie erkennt und behebt Plexicus CWE-1223?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-1223 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-1223?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/1223.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-1223

CWE-362 Parent

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CWE-366 Sibling

Race Condition within a Thread

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CWE-367 Sibling

Time-of-check Time-of-use (TOCTOU) Race Condition

This vulnerability occurs when a program verifies a resource's state (like a file's permissions or existence) but then uses it after that…

CWE-368 Sibling

Context Switching Race Condition

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CWE-421 Sibling

Race Condition During Access to Alternate Channel

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CWE-689 Sibling

Permission Race Condition During Resource Copy

This vulnerability occurs when a system copies a file or resource but delays setting its final permissions until the entire copy operation…

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