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-379 Base Incompleto
Creation of Temporary File in Directory with Insecure Permissions
This vulnerability occurs when an application creates a temporary file in a directory that is too permissive, allowing unauthorized users or processes to see, access, or manipulate the file.
Definición
What is CWE-379?
This vulnerability occurs when an application creates a temporary file in a directory that is too permissive, allowing unauthorized users or processes to see, access, or manipulate the file.
When a temporary file is placed in a directory with loose permissions (like world-readable or world-writable), other users or system actors can detect its presence. This simple act of discovery reveals which application created the file, offering a window into what the user is currently doing. Attackers can correlate this information with running processes to infer sensitive user activity, turning a seemingly minor information leak into a serious privacy breach.
This issue is more than just a file access problem; it's an information exposure flaw that can enable targeted attacks. By knowing which application is in use, an attacker gains critical context to craft further exploits, potentially escalating privileges or accessing confidential data. Developers must ensure temporary files are created in secure, private locations with strict access controls to prevent this form of reconnaissance.
Impacto en el mundo real
Real-world CVEs caused by CWE-379
-
A hotkey daemon written in Rust creates a domain socket file underneath /tmp, which is accessible by any user.
-
A Java-based application for a rapid-development framework uses File.createTempFile() to create a random temporary file with insecure default permissions.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
In the following code examples a temporary file is created and written to. After using the temporary file, the file is closed and deleted from the file system.
- 2
However, within this C/C++ code the method tmpfile() is used to create and open the temp file. The tmpfile() method works the same way as the fopen() method would with read/write permission, allowing attackers to read potentially sensitive information contained in the temp file or modify the contents of the file.
- 3
Similarly, the createTempFile() method used in the Java code creates a temp file that may be readable and writable to all users.
- 4
Additionally both methods used above place the file into a default directory. On UNIX systems the default directory is usually "/tmp" or "/var/tmp" and on Windows systems the default directory is usually "C:\\Windows\\Temp", which may be easily accessible to attackers, possibly enabling them to read and modify the contents of the temp file.
Ejemplo de código vulnerable
Vulnerable C
In the following code examples a temporary file is created and written to. After using the temporary file, the file is closed and deleted from the file system.
FILE *stream;
if( (stream = tmpfile()) == NULL ) {
perror("Could not open new temporary file\n");
return (-1);
}
```
// write data to tmp file*
...
// remove tmp file
rmtmp(); 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-379
- Requirements Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible.
- Implementation Try to store sensitive tempfiles in a directory which is not world readable -- i.e., per-user directories.
- Implementation Avoid using vulnerable temp file functions.
Señales de detección
How to detect CWE-379
Plexicus detecta automáticamente CWE-379 y abre un PR de corrección en menos de 60 segundos.
Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.
Preguntas frecuentes ¿Qué es CWE-379?
¿Qué gravedad tiene CWE-379?
¿Qué lenguajes o plataformas se ven afectados por CWE-379?
¿Cómo puedo prevenir CWE-379?
¿Cómo detecta y corrige Plexicus CWE-379?
¿Dónde puedo aprender más sobre CWE-379?
Frequently asked questions
¿Qué es CWE-379?
This vulnerability occurs when an application creates a temporary file in a directory that is too permissive, allowing unauthorized users or processes to see, access, or manipulate the file.
¿Qué gravedad tiene CWE-379?
MITRE califica la probabilidad de explotación como Baja — la explotación es poco frecuente, pero la debilidad debe corregirse cuando se descubra.
¿Qué lenguajes o plataformas se ven afectados por CWE-379?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-379?
Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible. Try to store sensitive tempfiles in a directory which is not world readable -- i.e., per-user directories.
¿Cómo detecta y corrige Plexicus CWE-379?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-379 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-379?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/379.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-379
CWE-377 Padre
Insecure Temporary File
This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing…
CWE-378 Hermano
Creation of Temporary File With Insecure Permissions
This vulnerability occurs when a program creates a temporary file but sets its file permissions too loosely, allowing other users or…
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