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 Incompleto
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.
Definición
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.
Impacto en el mundo real
Real-world CVEs caused by CWE-273
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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.
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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.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
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()
/../
} Ejemplo de código seguro
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.
Lista de prevención
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.
Señales de detección
How to detect CWE-273
CWE-273
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Preguntas frecuentes ¿Qué es CWE-273?
¿Qué gravedad tiene CWE-273?
¿Qué lenguajes o plataformas se ven afectados por CWE-273?
¿Cómo puedo prevenir CWE-273?
¿Cómo detecta y corrige Plexicus CWE-273?
¿Dónde puedo aprender más sobre CWE-273?
Frequently asked questions
¿Qué es CWE-273?
This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.
¿Qué gravedad tiene CWE-273?
MITRE califica la probabilidad de explotación como Media — la explotación es realista pero suele requerir condiciones específicas.
¿Qué lenguajes o plataformas se ven afectados por CWE-273?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir 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…
¿Cómo detecta y corrige Plexicus CWE-273?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-273 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-273?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/273.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-273
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Incorrect Check of Function Return Value
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CWE-354 Hermano
Improper Validation of Integrity Check Value
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CWE-391 Hermano
Unchecked Error Condition
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CWE-394 Hermano
Unexpected Status Code or Return Value
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NULL Pointer Dereference
This vulnerability occurs when a program attempts to access or manipulate memory using a pointer that is set to NULL, causing a crash or…
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Listo para validar lo que importa.
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