CWE-228 Class Incomplete

Improper Handling of Syntactically Invalid Structure

This vulnerability occurs when software fails to properly reject or process input that doesn't follow the expected format or structure, often leading to crashes or unexpected behavior.

Definition

What is CWE-228?

This vulnerability occurs when software fails to properly reject or process input that doesn't follow the expected format or structure, often leading to crashes or unexpected behavior.
When software expects data in a specific format—like JSON, XML, protocol messages, or file structures—it must rigorously validate that incoming input matches that exact syntax. If the code assumes the input is always well-formed and doesn't implement proper error handling for malformed data, attackers can exploit this by sending deliberately invalid structures. This can trigger unhandled exceptions, cause the application to crash, or bypass security checks that rely on correct parsing. To prevent this, developers should implement strict validation at all data entry points, using well-tested parsers and libraries instead of custom logic. Always define clear error-handling routines that safely reject invalid input without exposing internal details, and design systems to fail securely—defaulting to a denied state—when encountering unexpected syntax. Regular fuzz testing with invalid inputs helps uncover these hidden parsing weaknesses before attackers do.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-228

  • CVE-2004-0270

    Anti-virus product has assert error when line length is non-numeric.

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 Java

This Android application has registered to handle a URL when sent an intent:

Verwundbar Java 
```
...* 
  IntentFilter filter = new IntentFilter("com.example.URLHandler.openURL");
  MyReceiver receiver = new MyReceiver();
  registerReceiver(receiver, filter);
  
   *...* 
  
  public class UrlHandlerReceiver extends BroadcastReceiver {
  ```
  		@Override
  		public void onReceive(Context context, Intent intent) {
  				if("com.example.URLHandler.openURL".equals(intent.getAction())) {
  					String URL = intent.getStringExtra("URLToOpen");
  					int length = URL.length();
```
...* 
  				}}}
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-228

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Erkennungssignale

How to detect CWE-228

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-228 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-228?

This vulnerability occurs when software fails to properly reject or process input that doesn't follow the expected format or structure, often leading to crashes or unexpected behavior.

Wie gravierend ist CWE-228?

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-228 betroffen?

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

Wie kann ich CWE-228 verhindern?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Wie erkennt und behebt Plexicus CWE-228?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-228 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-228?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/228.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-228

CWE-707 Parent

Improper Neutralization

This vulnerability occurs when an application fails to properly validate or sanitize structured data before it's received from an external…

CWE-116 Sibling

Improper Encoding or Escaping of Output

This vulnerability occurs when an application builds a structured message—like a query, command, or request—for another component but…

CWE-138 Sibling

Improper Neutralization of Special Elements

This vulnerability occurs when an application accepts external input but fails to properly sanitize special characters or syntax that have…

CWE-1426 Sibling

Improper Validation of Generative AI Output

This vulnerability occurs when an application uses a generative AI model (like an LLM) but fails to properly check the AI's output before…

CWE-170 Sibling

Improper Null Termination

This weakness occurs when software fails to properly end a string or array with the required null character or equivalent terminator.

CWE-172 Sibling

Encoding Error

This vulnerability occurs when software incorrectly transforms data between different formats, leading to corrupted or misinterpreted…

CWE-182 Sibling

Collapse of Data into Unsafe Value

This vulnerability occurs when an application's data filtering or transformation process incorrectly merges or simplifies information,…

CWE-20 Sibling

Improper Input Validation

This vulnerability occurs when an application accepts data from an external source but fails to properly verify that the data is safe and…

CWE-240 Sibling

Improper Handling of Inconsistent Structural Elements

This vulnerability occurs when a system fails to properly manage situations where related data structures or elements should match but are…

Ressourcen

Further reading

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