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-273 Base Incomplet
Improper Check for Dropped Privileges
This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.
Définition
What is CWE-273?
This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.
When a program temporarily elevates its permissions to perform a sensitive task, it should reliably revert to a less-privileged state afterward. If the code doesn't properly confirm this privilege drop—perhaps due to a missing error check or a flawed verification logic—the application continues running with its elevated access rights.
This creates a critical security gap, as an attacker could potentially exploit the retained high privileges to perform unauthorized actions, access restricted data, or modify system settings. Essentially, the intended security boundary fails, leaving the system exposed to the very risks the privilege drop was meant to prevent.
Impact réel
Real-world CVEs caused by CWE-273
-
Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.
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Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.
Comment les attaquants l'exploitent
Parcours de l'attaquant étape par étape
- 1
Identifier un chemin de code qui traite des entrées non fiables sans validation.
- 2
Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.
- 3
Délivrer la charge utile via une requête normale et observer la réaction de l'application.
- 4
Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.
Exemple de code vulnérable
Vulnerable C++
This code attempts to take on the privileges of a user before creating a file, thus avoiding performing the action with unnecessarily high privileges:
bool DoSecureStuff(HANDLE hPipe) {
bool fDataWritten = false;
ImpersonateNamedPipeClient(hPipe);
HANDLE hFile = CreateFile(...);
/../
RevertToSelf()
/../
} 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-273
- Architecture and Design Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
- Implementation Check the results of all functions that return a value and verify that the value is expected.
- Implementation In Windows, make sure that the process token has the SeImpersonatePrivilege(Microsoft Server 2003). Code that relies on impersonation for security must ensure that the impersonation succeeded, i.e., that a proper privilege demotion happened.
Signaux de détection
How to detect CWE-273
CWE-273
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.
Questions fréquentes Qu'est-ce que CWE-273 ?
Quelle est la gravité de CWE-273 ?
Quels langages ou plateformes sont affectés par CWE-273 ?
Comment puis-je prévenir CWE-273 ?
Comment Plexicus détecte et corrige CWE-273 ?
Où puis-je en savoir plus sur CWE-273 ?
Frequently asked questions
Qu'est-ce que CWE-273 ?
This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.
Quelle est la gravité de CWE-273 ?
MITRE évalue la probabilité d'exploitation comme Moyenne — l'exploitation est réaliste mais nécessite généralement des conditions spécifiques.
Quels langages ou plateformes sont affectés par CWE-273 ?
MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.
Comment puis-je prévenir CWE-273 ?
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to…
Comment Plexicus détecte et corrige CWE-273 ?
Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-273 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-273 ?
MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/273.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.
Faiblesses associées
Weaknesses related to CWE-273
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CWE-391 Frère
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