Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-567 Base Brouillon
Unsynchronized Access to Shared Data in a Multithreaded Context
This vulnerability occurs when multiple threads in an application can read and modify shared data, like static variables, without proper coordination. This unsynchronized access corrupts data,…
Définition
What is CWE-567?
This vulnerability occurs when multiple threads in an application can read and modify shared data, like static variables, without proper coordination. This unsynchronized access corrupts data, causes crashes, and leads to unpredictable, often security-critical, behavior.
A common example is in Java servlet-based applications, where the framework manages multithreading. Developers might mistakenly treat static variables as safe, forgetting that all servlet threads can access them simultaneously. If an attacker can influence this shared data, one thread could inject invalid or malicious content that another thread then processes, creating a serious security flaw.
This issue is not limited to servlets or J2EE. It's a fundamental concurrency flaw that can appear in any multithreaded environment when developers assume single-threaded execution for shared resources. The core problem is a mismatch: the application uses a multithreaded architecture but fails to implement the necessary safeguards, like locks or atomic operations, to protect its shared state from concurrent modification.
Impact réel
Real-world CVEs caused by CWE-567
Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.
Comment les attaquants l'exploitent
Parcours de l'attaquant étape par étape
- 1
The following code implements a basic counter for how many times the page has been accesed.
- 2
Consider when two separate threads, Thread A and Thread B, concurrently handle two different requests:
- 3
- Assume this is the first occurrence of doGet, so the value of count is 0. - doGet() is called within Thread A. - The execution of doGet() in Thread A continues to the point AFTER the value of the count variable is read, then incremented, but BEFORE it is saved back to count. At this stage, the incremented value is 1, but the value of count is 0. - doGet() is called within Thread B, and due to a higher thread priority, Thread B progresses to the point where the count variable is accessed (where it is still 0), incremented, and saved. After the save, count is 1. - Thread A continues. It saves the intermediate, incremented value to the count variable - but the incremented value is 1, so count is "re-saved" to 1.
- 4
At this point, both Thread A and Thread B print that one hit has been seen, even though two separate requests have been processed. The value of count should be 2, not 1.
- 5
While this example does not have any real serious implications, if the shared variable in question is used for resource tracking, then resource consumption could occur. Other scenarios exist.
Exemple de code vulnérable
Vulnerable Java
The following code implements a basic counter for how many times the page has been accesed.
public static class Counter extends HttpServlet {
static int count = 0;
protected void doGet(HttpServletRequest in, HttpServletResponse out)
throws ServletException, IOException {
out.setContentType("text/plain");
PrintWriter p = out.getWriter();
count++;
p.println(count + " hits so far!");
}
} Exemple de code sécurisé
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.
Liste de contrôle de prévention
How to prevent CWE-567
- Implementation Remove the use of static variables used between servlets. If this cannot be avoided, use synchronized access for these variables.
Signaux de détection
How to detect CWE-567
Plexicus détecte automatiquement CWE-567 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.
Questions fréquentes Qu'est-ce que CWE-567 ?
Quelle est la gravité de CWE-567 ?
Quels langages ou plateformes sont affectés par CWE-567 ?
Comment puis-je prévenir CWE-567 ?
Comment Plexicus détecte et corrige CWE-567 ?
Où puis-je en savoir plus sur CWE-567 ?
Frequently asked questions
Qu'est-ce que CWE-567 ?
This vulnerability occurs when multiple threads in an application can read and modify shared data, like static variables, without proper coordination. This unsynchronized access corrupts data, causes crashes, and leads to unpredictable, often security-critical, behavior.
Quelle est la gravité de CWE-567 ?
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-567 ?
MITRE lists the following affected platforms: Java.
Comment puis-je prévenir CWE-567 ?
Remove the use of static variables used between servlets. If this cannot be avoided, use synchronized access for these variables.
Comment Plexicus détecte et corrige CWE-567 ?
Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-567 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-567 ?
MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/567.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.
Faiblesses associées
Weaknesses related to CWE-567
CWE-820 Parent
Missing Synchronization
This vulnerability occurs when multiple parts of your application (like threads or processes) use the same resource—such as a variable,…
CWE-1096 Frère
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CWE-543 Frère
Use of Singleton Pattern Without Synchronization in a Multithreaded Context
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CWE-488 Peut précéder
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