CWE-691 Pilier Brouillon

Insufficient Control Flow Management

This vulnerability occurs when a program's execution flow isn't properly managed, allowing attackers to bypass critical checks, trigger unexpected code paths, or disrupt normal operation.

Définition

What is CWE-691?

This vulnerability occurs when a program's execution flow isn't properly managed, allowing attackers to bypass critical checks, trigger unexpected code paths, or disrupt normal operation.
Insufficient control flow management happens when developers don't anticipate all possible execution states or fail to implement proper validation at decision points. This can include missing break statements in switch cases, poorly constructed loops that can be prematurely exited, or inadequate validation that allows attackers to skip over security checks. Without clear guardrails, the program's logic can be manipulated to reach code sections under unauthorized conditions. To prevent this, developers should implement strict state management and validate every transition in the program's logic flow. Use defensive programming techniques like complete condition coverage, explicit state machines, and mandatory checks before critical operations. Always assume that attackers will try to find unexpected paths through your code, and design your control flow to be resilient against such manipulation.
Impact réel

Real-world CVEs caused by CWE-691

  • CVE-2019-9805

    Chain: Creation of the packet client occurs before initialization is complete (CWE-696) resulting in a read from uninitialized memory (CWE-908), causing memory corruption.

  • CVE-2014-1266

    chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversary-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).

  • CVE-2011-1027

    Chain: off-by-one error (CWE-193) leads to infinite loop (CWE-835) using invalid hex-encoded characters.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    The following function attempts to acquire a lock in order to perform operations on a shared resource.

  2. 2

    However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.

  3. 3

    In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.

  4. 4

    In this example, the programmer has indented the statements to call Do_X() and Do_Y(), as if the intention is that these functions are only called when the condition is true. However, because there are no braces to signify the block, Do_Y() will always be executed, even if the condition is false.

  5. 5

    This might not be what the programmer intended. When the condition is critical for security, such as in making a security decision or detecting a critical error, this may produce a vulnerability.

Exemple de code vulnérable

Vulnerable C

The following function attempts to acquire a lock in order to perform operations on a shared resource.

Vulnérable C 
void f(pthread_mutex_t *mutex) {
  		pthread_mutex_lock(mutex);
```
/* access shared resource */* 
  		
  		
  		pthread_mutex_unlock(mutex);}
Exemple de code sécurisé

Secure C

In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.

Sécurisé C 
int f(pthread_mutex_t *mutex) {
  		int result;
  		result = pthread_mutex_lock(mutex);
  		if (0 != result)
  			return result;
```
/* access shared resource */* 
  		
  		
  		return pthread_mutex_unlock(mutex);}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-691

  • 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.
Signaux de détection

How to detect CWE-691

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-691 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-691 ?

This vulnerability occurs when a program's execution flow isn't properly managed, allowing attackers to bypass critical checks, trigger unexpected code paths, or disrupt normal operation.

Quelle est la gravité de CWE-691 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-691 ?

MITRE lists the following affected platforms: Not Technology-Specific.

Comment puis-je prévenir CWE-691 ?

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.

Comment Plexicus détecte et corrige CWE-691 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-691 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-691 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/691.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-691

CWE-1265 Enfant

Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls

This vulnerability occurs when a non-reentrant function is called, and during its execution, another call is triggered that unexpectedly…

CWE-1281 Enfant

Sequence of Processor Instructions Leads to Unexpected Behavior

Certain sequences of valid and invalid processor instructions can cause the CPU to lock up or behave unpredictably, often requiring a hard…

CWE-362 Enfant

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

A race condition occurs when multiple processes or threads access a shared resource simultaneously without proper coordination, creating a…

CWE-430 Enfant

Deployment of Wrong Handler

This vulnerability occurs when a system incorrectly assigns or routes an object to the wrong processing component.

CWE-431 Enfant

Missing Handler

This vulnerability occurs when a software component lacks the necessary code to properly handle an error or unexpected event.

CWE-662 Enfant

Improper Synchronization

This vulnerability occurs when a multi-threaded or multi-process application allows shared resources to be accessed by multiple threads or…

CWE-670 Enfant

Always-Incorrect Control Flow Implementation

This weakness occurs when a section of code is structured in a way that always executes incorrectly, regardless of input or conditions.…

CWE-696 Enfant

Incorrect Behavior Order

This weakness occurs when a system executes multiple dependent actions in the wrong sequence, leading to unexpected and potentially…

CWE-705 Enfant

Incorrect Control Flow Scoping

This vulnerability occurs when a program fails to return execution to the correct point in the code after finishing a specific operation…

Ressources

Further reading

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