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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
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Classic "Smurf" attack, using spoofed ICMP packets to broadcast addresses.
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DNS query with spoofed source address causes more traffic to be returned to spoofed address than was sent by the attacker.
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Large datagrams are sent in response to malformed datagrams.
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Game server sends a large amount.
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composite: NTP feature generates large responses (high amplification factor) with spoofed UDP source addresses.
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 Python
This code listens on a port for DNS requests and sends the result to the requesting address.
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
// 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
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-406
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-406?
Wie gravierend ist CWE-406?
Welche Sprachen oder Plattformen sind von CWE-406 betroffen?
Wie kann ich CWE-406 verhindern?
Wie erkennt und behebt Plexicus CWE-406?
Wo erfahre ich mehr über CWE-406?
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
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.