Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-647 Variant Incomplete
Use of Non-Canonical URL Paths for Authorization Decisions
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using…
Definition
What is CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
Applications often define access rules for specific URLs, but many different URL formats can point to the same page. If the authorization check doesn't first convert URLs to a canonical (standardized) form, attackers can use variations like different character encodings, case changes, IP addresses instead of domain names, trailing slashes, or explicit port numbers to bypass security checks. Each variation appears different to the authorization system while loading the same protected content.
To prevent this, always normalize URLs to a single canonical format before checking permissions. Implement a default-deny approach that rejects any non-standard URL format. This involves stripping unnecessary elements like default ports, removing trailing slashes, converting to lowercase, decoding encoded characters, and resolving hostnames consistently before any authorization decision is made.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-647
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 pseudo
MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Sicheres Codebeispiel
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} 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-647
- Architecture and Design Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form.
- Architecture and Design Reject all alternate path encodings that are not in the expected canonical form.
Erkennungssignale
How to detect CWE-647
CWE-647
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-647?
Wie gravierend ist CWE-647?
Welche Sprachen oder Plattformen sind von CWE-647 betroffen?
Wie kann ich CWE-647 verhindern?
Wie erkennt und behebt Plexicus CWE-647?
Wo erfahre ich mehr über CWE-647?
Frequently asked questions
Was ist CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
Wie gravierend ist CWE-647?
MITRE stuft die Exploit-Wahrscheinlichkeit als hoch ein — diese Schwachstelle wird aktiv in freier Wildbahn ausgenutzt und sollte priorisiert behoben werden.
Welche Sprachen oder Plattformen sind von CWE-647 betroffen?
MITRE lists the following affected platforms: Web Server.
Wie kann ich CWE-647 verhindern?
Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form. Reject all alternate path encodings that are not in the expected canonical form.
Wie erkennt und behebt Plexicus CWE-647?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-647 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-647?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/647.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-647
CWE-863 Parent
Incorrect Authorization
This vulnerability occurs when an application checks if a user is allowed to perform an action or access data, but the check is flawed or…
CWE-1244 Sibling
Internal Asset Exposed to Unsafe Debug Access Level or State
This vulnerability occurs when a system's debug or test interface supports multiple access levels, but an internal asset is incorrectly…
CWE-551 Sibling
Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
This vulnerability occurs when a web server checks access permissions before fully processing and normalizing a URL, potentially allowing…
CWE-639 Sibling
Authorization Bypass Through User-Controlled Key
This vulnerability occurs when an application's authorization system fails to verify that a user is allowed to access specific data before…
CWE-804 Sibling
Guessable CAPTCHA
This vulnerability occurs when a CAPTCHA challenge is too easy for automated bots to solve, either by guessing or using pattern…
CWE-942 Sibling
Permissive Cross-domain Security Policy with Untrusted Domains
This vulnerability occurs when a web application's cross-domain security policy, like a Content Security Policy (CSP), explicitly allows…
Ressourcen
Further reading
Bereit, das Wesentliche zu validieren?
Bereit zu validieren, was zählt.
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