Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.
CWE-640 Base Incomplete
Weak Password Recovery Mechanism for Forgotten Password
This vulnerability occurs when an application's password reset or recovery feature is poorly designed or implemented, allowing attackers to bypass authentication and hijack user accounts.
Definition
What is CWE-640?
This vulnerability occurs when an application's password reset or recovery feature is poorly designed or implemented, allowing attackers to bypass authentication and hijack user accounts.
Password recovery is a necessary feature, but it often becomes the weakest link in your authentication system. Common flaws include using easily guessed security questions (answers found on social media), sending the original password instead of a secure temporary one, or failing to limit reset attempts, which enables denial-of-service attacks. Attackers exploit these oversights to impersonate legitimate users, completely undermining even strong initial password policies.
To prevent this, treat the recovery mechanism with the same security rigor as the primary login. Always generate a time-limited, single-use token sent to a pre-verified contact method. Implement robust rate-limiting and audit logs for all recovery attempts. The goal is to verify the user's identity securely without creating a new, exploitable path into the account.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-640
Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.
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 pseudo
MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.
// 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
// 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-640
- Architecture and Design Make sure that all input supplied by the user to the password recovery mechanism is thoroughly filtered and validated.
- Architecture and Design Do not use standard weak security questions and use several security questions.
- Architecture and Design Make sure that there is throttling on the number of incorrect answers to a security question. Disable the password recovery functionality after a certain (small) number of incorrect guesses.
- Architecture and Design Require that the user properly answers the security question prior to resetting their password and sending the new password to the e-mail address of record.
- Architecture and Design Never allow the user to control what e-mail address the new password will be sent to in the password recovery mechanism.
- Architecture and Design Assign a new temporary password rather than revealing the original password.
Erkennungssignale
How to detect CWE-640
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-640
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-640?
Wie gravierend ist CWE-640?
Welche Sprachen oder Plattformen sind von CWE-640 betroffen?
Wie kann ich CWE-640 verhindern?
Wie erkennt und behebt Plexicus CWE-640?
Wo erfahre ich mehr über CWE-640?
Frequently asked questions
Was ist CWE-640?
This vulnerability occurs when an application's password reset or recovery feature is poorly designed or implemented, allowing attackers to bypass authentication and hijack user accounts.
Wie gravierend ist CWE-640?
MITRE stuft die Exploit-Wahrscheinlichkeit als hoch ein — diese Schwachstelle wird aktiv in freier Wildbahn ausgenutzt und sollte priorisiert behoben werden.
Welche Sprachen oder Plattformen sind von CWE-640 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-640 verhindern?
Make sure that all input supplied by the user to the password recovery mechanism is thoroughly filtered and validated. Do not use standard weak security questions and use several security questions.
Wie erkennt und behebt Plexicus CWE-640?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-640 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-640?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/640.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-640
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-1391 Sibling
Use of Weak Credentials
This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily…
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…
Ressourcen
Further reading
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Bereit zu validieren, was zählt.
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