CWE-1391 Class Incomplete

Use of Weak Credentials

This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily guessable values—that an attacker can deduce, reuse, or predict…

Definition

What is CWE-1391?

This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily guessable values—that an attacker can deduce, reuse, or predict without needing to perform a full brute-force attack.
Authentication systems are designed to force attackers into time-consuming brute-force attempts when credentials are unknown. However, when credentials are weak—whether they are static, widely reused, or generated in a predictable pattern—attackers can bypass this protection entirely, gaining unauthorized access with minimal effort. Weak credentials typically fall into three categories: hard-coded (static and unchangeable), default (common across installations but changeable), or predictable (generated using a flawed or guessable method). Even if a unique credential is intended for each deployment, a predictable generation process can still make it vulnerable to efficient guessing attacks, undermining the entire authentication mechanism.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-1391

  • [REF-1374]

    Chain: JavaScript-based cryptocurrency library can fall back to the insecure Math.random() function instead of reporting a failure (CWE-392), thus reducing the entropy (CWE-332) and leading to generation of non-unique cryptographic keys for Bitcoin wallets (CWE-1391)

  • CVE-2022-30270

    Remote Terminal Unit (RTU) uses default credentials for some SSH accounts

  • CVE-2022-29965

    Distributed Control System (DCS) uses a deterministic algorithm to generate utility passwords

  • CVE-2022-30271

    Remote Terminal Unit (RTU) uses a hard-coded SSH private key that is likely to be used in typical deployments

  • CVE-2021-38759

    microcontroller board has default password, allowing admin access

  • CVE-2021-41192

    data visualization/sharing package uses default secret keys or cookie values if they are not specified in environment variables

  • CVE-2020-8994

    UART interface for AI speaker uses empty password for root shell

  • CVE-2020-27020

    password manager does not generate cryptographically strong passwords, allowing prediction of passwords using guessable details such as time of generation

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 pseudo

MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.

Verwundbar pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
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-1391

  • 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-1391

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-1391 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-1391?

This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily guessable values—that an attacker can deduce, reuse, or predict without needing to perform a full brute-force attack.

Wie gravierend ist CWE-1391?

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-1391 betroffen?

MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, ICS/OT, Not Technology-Specific.

Wie kann ich CWE-1391 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-1391?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-1391 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-1391?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/1391.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-1391

CWE-1390 Parent

Weak Authentication

This vulnerability occurs when a system's login or identity verification process is too easy to bypass or fool. While it attempts to check…

CWE-262 Sibling

Not Using Password Aging

This vulnerability occurs when a system lacks password expiration policies, allowing users to keep the same password indefinitely.

CWE-263 Sibling

Password Aging with Long Expiration

The system enforces password changes, but the time allowed between changes is excessively long, weakening security.

CWE-289 Sibling

Authentication Bypass by Alternate Name

This vulnerability occurs when a system checks access based on a resource or user name, but fails to account for all the different names…

CWE-290 Sibling

Authentication Bypass by Spoofing

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing…

CWE-294 Sibling

Authentication Bypass by Capture-replay

This vulnerability occurs when an attacker can intercept and record legitimate authentication traffic, then replay it later to gain…

CWE-301 Sibling

Reflection Attack in an Authentication Protocol

A reflection attack is a flaw in mutual authentication protocols that allows an attacker to impersonate a legitimate user without knowing…

CWE-302 Sibling

Authentication Bypass by Assumed-Immutable Data

This vulnerability occurs when an authentication system incorrectly treats certain data as unchangeable, when in fact an attacker can…

CWE-303 Sibling

Incorrect Implementation of Authentication Algorithm

This weakness occurs when a developer implements a standard authentication algorithm, but makes critical mistakes in the code that cause…

Ressourcen

Further reading

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