CWE-453 Variant Draft

Insecure Default Variable Initialization

This vulnerability occurs when software sets an internal variable to an insecure or unnecessarily weak default value during initialization, rather than using the most secure option available.

Definition

What is CWE-453?

This vulnerability occurs when software sets an internal variable to an insecure or unnecessarily weak default value during initialization, rather than using the most secure option available.
Insecure default initialization happens when a developer or framework assigns a starting value to a variable that is inherently vulnerable. Common examples include enabling debug modes, using weak cryptographic keys, granting excessive permissions, or turning security features off by default. This creates a hidden security gap because the system starts in a weakened state, often without the administrator or end-user being aware that they need to change a setting to be secure. To prevent this, developers should adopt a 'secure by default' design principle. This means the initial configuration should be the most restrictive and safest possible, requiring explicit action to loosen security, not the other way around. Always validate that security-critical variables like encryption settings, authentication flags, and privilege levels are initialized to their strongest values, and ensure documentation clearly warns against using insecure defaults.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-453

  • CVE-2022-36349

    insecure default variable initialization in BIOS firmware for a hardware board allows DoS

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    This code attempts to login a user using credentials from a POST request:

  2. 2

    Because the $authorized variable is never initialized, PHP will automatically set $authorized to any value included in the POST request if register_globals is enabled. An attacker can send a POST request with an unexpected third value 'authorized' set to 'true' and gain authorized status without supplying valid credentials.

  3. 3

    Here is a fixed version:

  4. 4

    This code avoids the issue by initializing the $authorized variable to false and explicitly retrieving the login credentials from the $_POST variable. Regardless, register_globals should never be enabled and is disabled by default in current versions of PHP.

Verwundbares Codebeispiel

Vulnerable PHP

This code attempts to login a user using credentials from a POST request:

Verwundbar PHP 
```
// $user and $pass automatically set from POST request* 
  if (login_user($user,$pass)) {
  ```
  	$authorized = true;
  }
```
...* 
  
  if ($authorized) {
  ```
  	generatePage();
  }
Sicheres Codebeispiel

Secure PHP

Here is a fixed version:

Sicher PHP 
$user = $_POST['user'];
  $pass = $_POST['pass'];
  $authorized = false;
  if (login_user($user,$pass)) {
  	$authorized = true;
  }
```
...*
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-453

  • System Configuration Disable or change default settings when they can be used to abuse the system. Since those default settings are shipped with the product they are likely to be known by a potential attacker who is familiar with the product. For instance, default credentials should be changed or the associated accounts should be disabled.
Erkennungssignale

How to detect CWE-453

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-453 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-453?

This vulnerability occurs when software sets an internal variable to an insecure or unnecessarily weak default value during initialization, rather than using the most secure option available.

Wie gravierend ist CWE-453?

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-453 betroffen?

MITRE lists the following affected platforms: PHP.

Wie kann ich CWE-453 verhindern?

Disable or change default settings when they can be used to abuse the system. Since those default settings are shipped with the product they are likely to be known by a potential attacker who is familiar with the product. For instance, default credentials should be changed or the associated accounts should be disabled.

Wie erkennt und behebt Plexicus CWE-453?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-453 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-453?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/453.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-453

CWE-1188 Parent

Initialization of a Resource with an Insecure Default

This vulnerability occurs when software uses an insecure default setting or value for a resource, assuming an administrator will change it…

Ressourcen

Further reading

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