CWE-293 Variant Draft High likelihood

Using Referer Field for Authentication

This vulnerability occurs when a web application uses the HTTP Referer header as a sole or primary method for authentication or authorization decisions. Since this header is entirely controlled by…

Definition

What is CWE-293?

This vulnerability occurs when a web application uses the HTTP Referer header as a sole or primary method for authentication or authorization decisions. Since this header is entirely controlled by the user's browser or client and can be easily forged, it provides no reliable security.
The HTTP Referer header is designed to tell a server which page a user came from, but it was never intended for security. Treating it as a trusted credential is like using a 'recommended by a friend' note for building access—anyone can write it. Developers might implement this check to prevent cross-site request forgery (CSRF) or to restrict direct URL access, but because attackers can fully manipulate the header with simple tools like a proxy or browser extension, this defense is completely ineffective. To properly secure authentication and authorization, always use established server-side mechanisms like session tokens, CSRF tokens, or standard authentication protocols (OAuth, SAML). These methods rely on secrets or cryptographic signatures that the client cannot easily forge. Relying on the Referer header creates a false sense of security and leaves critical application functions exposed to trivial bypass attacks.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-293

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

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 C++

The following code samples check a packet's referer in order to decide whether or not an inbound request is from a trusted host.

Verwundbar C++ 
String trustedReferer = "http://www.example.com/"
  while(true){
  	n = read(newsock, buffer, BUFSIZE);
  	requestPacket = processPacket(buffer, n);
  	if (requestPacket.referer == trustedReferer){
  		openNewSecureSession(requestPacket);
  	}
  }
Sicheres Codebeispiel

Secure pseudo

Sicher 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-293

  • Architecture and Design In order to usefully check if a given action is authorized, some means of strong authentication and method protection must be used. Use other means of authorization that cannot be simply spoofed. Possibilities include a username/password or certificate.
Erkennungssignale

How to detect CWE-293

Automated Static Analysis High

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.)

Plexicus Auto-Fix

Plexicus erkennt CWE-293 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-293?

This vulnerability occurs when a web application uses the HTTP Referer header as a sole or primary method for authentication or authorization decisions. Since this header is entirely controlled by the user's browser or client and can be easily forged, it provides no reliable security.

Wie gravierend ist CWE-293?

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-293 betroffen?

MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.

Wie kann ich CWE-293 verhindern?

In order to usefully check if a given action is authorized, some means of strong authentication and method protection must be used. Use other means of authorization that cannot be simply spoofed. Possibilities include a username/password or certificate.

Wie erkennt und behebt Plexicus CWE-293?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-293 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-293?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/293.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-293

CWE-290 Parent

Authentication Bypass by Spoofing

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing…

CWE-291 Sibling

Reliance on IP Address for Authentication

This vulnerability occurs when a system uses a client's IP address as the sole or primary method to verify their identity.

CWE-350 Sibling

Reliance on Reverse DNS Resolution for a Security-Critical Action

This vulnerability occurs when an application uses a reverse DNS lookup on an IP address to get a hostname and then uses that hostname for…

Ressourcen

Further reading

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