CWE-221 Class Incomplete

Information Loss or Omission

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.

Definition

What is CWE-221?

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.
When a system doesn't capture key details like authentication failures, access violations, or input errors, security teams lose the visibility needed to detect and respond to attacks. This omission creates blind spots, making it difficult to understand an attack's origin, method, and impact, ultimately weakening your security posture. This problem can also be a side effect of another vulnerability. For instance, a severe issue like a buffer overflow might cause a program to crash abruptly before it has a chance to write any log entry about the anomalous event. This means the root cause remains hidden, complicating forensic analysis and delaying the fix for the underlying flaw.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-221

  • CVE-2004-2227

    Web browser's filename selection dialog only shows the beginning portion of long filenames, which can trick users into launching executables with dangerous extensions.

  • CVE-2003-0412

    application server does not log complete URI of a long request (truncation).

  • CVE-1999-1029

    Login attempts are not recorded if the user disconnects before the maximum number of tries.

  • CVE-2002-0725

    Attacker performs malicious actions on a hard link to a file, obscuring the real target file.

  • CVE-1999-1055

    Product does not warn user when document contains certain dangerous functions or macros.

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 PHP

This code logs suspicious multiple login attempts.

Verwundbar PHP 
function login($userName,$password){
  		if(authenticate($userName,$password)){
  			return True;
  		}
  		else{
  			incrementLoginAttempts($userName);
  			if(recentLoginAttempts($userName) > 5){
  				writeLog("Failed login attempt by User: " . $userName . " at " + date('r') );
  			}
  		}
  }
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-221

  • 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-221

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-221 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-221?

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.

Wie gravierend ist CWE-221?

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-221 betroffen?

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

Wie kann ich CWE-221 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-221?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-221 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-221?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/221.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-221

CWE-664 Parent

Improper Control of a Resource Through its Lifetime

This vulnerability occurs when software fails to properly manage a resource throughout its entire lifecycle—from creation and active use…

CWE-118 Sibling

Incorrect Access of Indexable Resource ('Range Error')

This vulnerability occurs when software fails to properly check the boundaries of an indexed resource, like an array, buffer, or file,…

CWE-1229 Sibling

Creation of Emergent Resource

This vulnerability occurs when a system's normal operations unintentionally create new, exploitable resources that attackers can use to…

CWE-1250 Sibling

Improper Preservation of Consistency Between Independent Representations of Shared State

This vulnerability occurs when a system with multiple independent components (like distributed services or separate hardware units) each…

CWE-1329 Sibling

Reliance on Component That is Not Updateable

This vulnerability occurs when a product depends on a component that cannot be updated or patched to fix security flaws or critical bugs.

CWE-372 Sibling

Incomplete Internal State Distinction

This vulnerability occurs when an application fails to accurately track its own operational state. The system incorrectly assumes it's in…

CWE-400 Sibling

Uncontrolled Resource Consumption

This vulnerability occurs when an application fails to properly manage a finite resource, allowing an attacker to exhaust it and cause a…

CWE-404 Sibling

Improper Resource Shutdown or Release

This vulnerability occurs when a program fails to properly close or release a system resource—like a file handle, database connection, or…

CWE-410 Sibling

Insufficient Resource Pool

This vulnerability occurs when a system's resource pool is too small to handle maximum usage. Attackers can exploit this by making a high…

Ressourcen

Further reading

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