Some tools can act as proxy servers that allow the tester to intercept packets or messages, inspect them, and modify them before sending them to the destination in order to see if the modified packets are still accepted by the receiving component.
CWE-300 Class Draft
Channel Accessible by Non-Endpoint
This vulnerability occurs when a system fails to properly verify who is on the other end of a communication link or to secure the channel itself. This allows an unauthorized third party to access or…
Definition
What is CWE-300?
This vulnerability occurs when a system fails to properly verify who is on the other end of a communication link or to secure the channel itself. This allows an unauthorized third party to access or manipulate the communication as if they were a legitimate participant.
Secure communication requires confidently knowing who you're talking to at both ends of the connection. If a system performs weak, inconsistent, or missing identity checks, it can't be sure if the other party is genuine. Attackers exploit this gap by inserting themselves into the channel, impersonating a trusted endpoint. Once in the middle, they can silently eavesdrop on or alter the data flowing between the two original, unsuspecting parties.
For developers, the core issue is misplaced trust. Without robust endpoint verification—like mutual authentication—your application might share sensitive data with an impostor. To prevent this, ensure your implementation validates identities at both ends using strong, cryptographic methods and maintains the channel's integrity to block unauthorized access or tampering.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-300
-
chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversry-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).
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 Java
In the Java snippet below, data is sent over an unencrypted channel to a remote server.
Socket sock;
PrintWriter out;
try {
sock = new Socket(REMOTE_HOST, REMOTE_PORT);
out = new PrintWriter(echoSocket.getOutputStream(), true);
```
// Write data to remote host via socket output stream.*
...} 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-300
- Implementation Always fully authenticate both ends of any communications channel.
- Architecture and Design Adhere to the principle of complete mediation.
- Implementation A certificate binds an identity to a cryptographic key to authenticate a communicating party. Often, the certificate takes the encrypted form of the hash of the identity of the subject, the public key, and information such as time of issue or expiration using the issuer's private key. The certificate can be validated by deciphering the certificate with the issuer's public key. See also X.509 certificate signature chains and the PGP certification structure.
Erkennungssignale
How to detect CWE-300
Dynamic Application Security Testing (DAST) tools can be used to detect network traffic without encryption and/or verification. The affected protocol may be subject to Adversary-in-the-Middle attacks. Some tools act as proxy servers that allow the tester to inspect and modify packets/messages to see if they are still accepted by the receiving component.
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.) The analysis could identify use of protocols that are subject to Adversary-in-the-Middle attacks.
Plexicus erkennt CWE-300 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.
Häufig gestellte Fragen Was ist CWE-300?
Wie gravierend ist CWE-300?
Welche Sprachen oder Plattformen sind von CWE-300 betroffen?
Wie kann ich CWE-300 verhindern?
Wie erkennt und behebt Plexicus CWE-300?
Wo erfahre ich mehr über CWE-300?
Frequently asked questions
Was ist CWE-300?
This vulnerability occurs when a system fails to properly verify who is on the other end of a communication link or to secure the channel itself. This allows an unauthorized third party to access or manipulate the communication as if they were a legitimate participant.
Wie gravierend ist CWE-300?
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-300 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-300 verhindern?
Always fully authenticate both ends of any communications channel. Adhere to the principle of complete mediation.
Wie erkennt und behebt Plexicus CWE-300?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-300 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-300?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/300.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-300
CWE-923 Parent
Improper Restriction of Communication Channel to Intended Endpoints
This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually…
CWE-1275 Sibling
Sensitive Cookie with Improper SameSite Attribute
This vulnerability occurs when a sensitive cookie does not have a secure SameSite attribute configured, leaving it exposed to cross-site…
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-297 Sibling
Improper Validation of Certificate with Host Mismatch
This vulnerability occurs when an application accepts a valid SSL/TLS certificate without properly verifying that it actually belongs to…
CWE-419 Sibling
Unprotected Primary Channel
This vulnerability occurs when an application exposes a privileged administrative interface or restricted functionality through a primary…
CWE-420 Sibling
Unprotected Alternate Channel
This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker…
CWE-940 Sibling
Improper Verification of Source of a Communication Channel
This vulnerability occurs when an application accepts incoming communication requests without properly checking where they originate from,…
CWE-941 Sibling
Incorrectly Specified Destination in a Communication Channel
This vulnerability occurs when an application establishes an outgoing communication channel but fails to correctly define or enforce the…
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
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