CWE-406 Class Incomplete

Insufficient Control of Network Message Volume (Network Amplification)

This vulnerability occurs when a system fails to properly limit the amount of network traffic it can generate in response to a request, allowing an attacker to abuse it to send a disproportionately…

Definition

What is CWE-406?

This vulnerability occurs when a system fails to properly limit the amount of network traffic it can generate in response to a request, allowing an attacker to abuse it to send a disproportionately large volume of data.
Without clear limits on how much traffic a single user or request can trigger, a system cannot tell the difference between normal operations and an attack designed to amplify traffic. Attackers exploit this by sending small, seemingly innocent requests that force the system to generate massive, overwhelming responses. This turns the vulnerable application into an unwitting participant in a denial-of-service attack against other targets. To prevent this, systems need a defined resource policy that tracks and caps outgoing transmissions based on client identity, privilege, or request type. Implementing such controls—like rate limiting, traffic quotas, or monitoring for abnormal response sizes—ensures that no single entity can commandeer your network resources to launch an amplified attack.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-406

  • CVE-1999-0513

    Classic "Smurf" attack, using spoofed ICMP packets to broadcast addresses.

  • CVE-1999-1379

    DNS query with spoofed source address causes more traffic to be returned to spoofed address than was sent by the attacker.

  • CVE-2000-0041

    Large datagrams are sent in response to malformed datagrams.

  • CVE-1999-1066

    Game server sends a large amount.

  • CVE-2013-5211

    composite: NTP feature generates large responses (high amplification factor) with spoofed UDP source addresses.

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 Python

This code listens on a port for DNS requests and sends the result to the requesting address.

Verwundbar Python 
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  sock.bind( (UDP_IP,UDP_PORT) )
  while true:
  		data = sock.recvfrom(1024)
  		if not data:
  			break
  		(requestIP, nameToResolve) = parseUDPpacket(data)
  		record = resolveName(nameToResolve)
  		sendResponse(requestIP,record)
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-406

  • Architecture and Design An application must make network resources available to a client commensurate with the client's access level.
  • Policy Define a clear policy for network resource allocation and consumption.
  • Implementation An application must, at all times, keep track of network resources and meter their usage appropriately.
Erkennungssignale

How to detect CWE-406

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-406 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-406?

This vulnerability occurs when a system fails to properly limit the amount of network traffic it can generate in response to a request, allowing an attacker to abuse it to send a disproportionately large volume of data.

Wie gravierend ist CWE-406?

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-406 betroffen?

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

Wie kann ich CWE-406 verhindern?

An application must make network resources available to a client commensurate with the client's access level. Define a clear policy for network resource allocation and consumption.

Wie erkennt und behebt Plexicus CWE-406?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-406 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-406?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/406.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-406

CWE-405 Parent

Asymmetric Resource Consumption (Amplification)

This vulnerability occurs when a system allows an attacker to trigger a disproportionate amount of resource consumption—like CPU, memory,…

CWE-1050 Sibling

Excessive Platform Resource Consumption within a Loop

This vulnerability occurs when a loop contains code that repeatedly consumes critical system resources like file handles, database…

CWE-1072 Sibling

Data Resource Access without Use of Connection Pooling

This weakness occurs when an application creates a new database connection for every request instead of using a managed connection pool.…

CWE-1073 Sibling

Non-SQL Invokable Control Element with Excessive Number of Data Resource Accesses

This weakness occurs when a client-side function or method makes an excessive number of individual data requests through a non-SQL data…

CWE-1084 Sibling

Invokable Control Element with Excessive File or Data Access Operations

This weakness occurs when a single function or method performs an excessive number of file or database operations, such as repeated reads,…

CWE-1089 Sibling

Large Data Table with Excessive Number of Indices

This weakness occurs when an application uses a database table with a very large number of rows and creates too many indexes on it,…

CWE-1094 Sibling

Excessive Index Range Scan for a Data Resource

This weakness occurs when a database query performs an index range scan that can access an unnecessarily large number of rows from a…

CWE-1176 Sibling

Inefficient CPU Computation

This weakness occurs when software uses inefficient algorithms or suboptimal CPU operations, performing unnecessary or overly complex…

CWE-407 Sibling

Inefficient Algorithmic Complexity

This vulnerability occurs when a software component uses an algorithm with poor worst-case performance. An attacker can exploit this by…

Ressourcen

Further reading

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