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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
-
insecure default variable initialization in BIOS firmware for a hardware board allows DoS
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
This code attempts to login a user using credentials from a POST request:
- 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
Here is a fixed version:
- 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:
```
// $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:
$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
Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.
Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.
Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.
CWE-453
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Häufig gestellte Fragen Was ist CWE-453?
Wie gravierend ist CWE-453?
Welche Sprachen oder Plattformen sind von CWE-453 betroffen?
Wie kann ich CWE-453 verhindern?
Wie erkennt und behebt Plexicus CWE-453?
Wo erfahre ich mehr über CWE-453?
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
Ressourcen
Further reading
Bereit, das Wesentliche zu validieren?
Bereit zu validieren, was zählt.
Plexicus ist Proof-Driven AppSec: validierte Funde, kontextuelles Verständnis und geprüfte Remediation — in Evidenz verankert, mit Ihnen gescoped.