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.
Definição
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 no 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.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 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.
Exemplo de código vulnerável
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(); Exemplo 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 verificação de prevenção
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.
Sinais de deteção
How to detect CWE-379
O Plexicus deteta automaticamente o CWE-379 e abre um PR de correção em menos de 60 segundos.
O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.
Perguntas frequentes O que é o CWE-379?
Qual a gravidade do CWE-379?
Que linguagens ou plataformas são afetadas pelo CWE-379?
Como posso prevenir o CWE-379?
Como é que o Plexicus deteta e corrige o CWE-379?
Onde posso saber mais sobre o CWE-379?
Frequently asked questions
O que é o 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.
Qual a gravidade do CWE-379?
A MITRE classifica a probabilidade de exploração como Baixa — a exploração é pouco comum, mas a fraqueza deve mesmo assim ser corrigida quando descoberta.
Que linguagens ou plataformas são afetadas pelo CWE-379?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o 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.
Como é que o Plexicus deteta e corrige o CWE-379?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-379 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-379?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/379.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-379
CWE-377 Pai
Insecure Temporary File
This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing…
CWE-378 Irmão
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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