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CWE-649 Base Incomplete
Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered.…
Definition
What is CWE-649?
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered. Without integrity checks, the system cannot detect if an attacker has tampered with these inputs.
Applications often hide or encrypt client-side data that influences server-side decisions, such as user permissions or system state. However, if the server only decodes or de-obfuscates this data without verifying its authenticity, an attacker can systematically guess or modify values to elevate privileges, access sensitive information, or alter application behavior. Obfuscation and weak encryption are designed for confidentiality, not integrity—they cannot prevent tampering.
To prevent this, developers must implement robust integrity checks like digital signatures or HMACs alongside any obfuscation or encryption. These mechanisms allow the server to confirm that the data hasn't been changed since it was originally issued. Relying solely on hiding data is insufficient; you must actively validate its trustworthiness before using it for security-critical operations.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-649
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An IPSec configuration does not perform integrity checking of the IPSec packet as the result of either not configuring ESP properly to support the integrity service or using AH improperly. In either case, the security gateway receiving the IPSec packet would not validate the integrity of the packet to ensure that it was not changed. Thus if the packets were intercepted the attacker could undetectably change some of the bits in the packets. The meaningful bit flipping was possible due to the known weaknesses in the CBC encryption mode. Since the attacker knew the structure of the packet, they were able (in one variation of the attack) to use bit flipping to change the destination IP of the packet to the destination machine controlled by the attacker. And so the destination security gateway would decrypt the packet and then forward the plaintext to the machine controlled by the attacker. The attacker could then read the original message. For instance if VPN was used with the vulnerable IPSec configuration the attacker could read the victim's e-mail. This vulnerability demonstrates the need to enforce the integrity service properly when critical data could be modified by an attacker. This problem might have also been mitigated by using an encryption mode that is not susceptible to bit flipping attacks, but the preferred mechanism to address this problem still remains message verification for integrity. While this attack focuses on the network layer and requires an entity that controls part of the communication path such as a router, the situation is not much different at the software level, where an attacker can modify tokens/parameters used by the application.
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-649
- Architecture and Design Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side.
- Architecture and Design Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.
- Architecture and Design Client side tokens/parameters should not be such that it would be easy/predictable to guess another valid state.
- Architecture and Design Obfuscation should not be relied upon. If encryption is used, it needs to be properly applied (i.e. proven algorithm and implementation, use padding, use random initialization vector, user proper encryption mode). Even with proper encryption where the ciphertext does not leak information about the plaintext or reveal its structure, compromising integrity is possible (although less likely) without the provision of the integrity service.
Erkennungssignale
How to detect CWE-649
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.
Plexicus erkennt CWE-649 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.
Häufig gestellte Fragen Was ist CWE-649?
Wie gravierend ist CWE-649?
Welche Sprachen oder Plattformen sind von CWE-649 betroffen?
Wie kann ich CWE-649 verhindern?
Wie erkennt und behebt Plexicus CWE-649?
Wo erfahre ich mehr über CWE-649?
Frequently asked questions
Was ist CWE-649?
This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered. Without integrity checks, the system cannot detect if an attacker has tampered with these inputs.
Wie gravierend ist CWE-649?
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-649 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-649 verhindern?
Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side. Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.
Wie erkennt und behebt Plexicus CWE-649?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-649 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-649?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/649.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-649
CWE-345 Parent
Insufficient Verification of Data Authenticity
This vulnerability occurs when an application fails to properly check where data comes from or confirm its legitimacy, allowing untrusted…
CWE-1293 Sibling
Missing Source Correlation of Multiple Independent Data
This vulnerability occurs when a system trusts a single source of data without verification, making it impossible to detect if that source…
CWE-346 Sibling
Origin Validation Error
This vulnerability occurs when an application fails to properly confirm the true origin of incoming data or communication, allowing…
CWE-347 Sibling
Improper Verification of Cryptographic Signature
This vulnerability occurs when an application fails to properly check the digital signature on data, or skips the verification step…
CWE-348 Sibling
Use of Less Trusted Source
This vulnerability occurs when a system has access to multiple sources for the same critical data, but it chooses to rely on the less…
CWE-349 Sibling
Acceptance of Extraneous Untrusted Data With Trusted Data
This vulnerability occurs when a system processes both trusted and untrusted data together, but fails to separate them. The application…
CWE-351 Sibling
Insufficient Type Distinction
This vulnerability occurs when an application fails to properly differentiate between different types of data or objects, leading to…
CWE-352 Sibling
Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) happens when a web application cannot reliably tell if a user actually intended to submit a request,…
CWE-353 Sibling
Missing Support for Integrity Check
This vulnerability occurs when a system uses a communication protocol that lacks built-in integrity verification, such as a checksum or…
Ressourcen
Further reading
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