# Cwe 377 Insecure Temporary File

> Use this skill when you need to remediate CWE-377 (Insecure Temporary File) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing insecure temporary file issues.

- Skill: `developerscoffee/cwe-377-insecure-temporary-file` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-377-insecure-temporary-file`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-377-insecure-temporary-file/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- License: MIT
- Author: DevelopersCoffee (https://skillmd.com/u/developerscoffee)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/developerscoffee/cwe-377-insecure-temporary-file

---


# CWE-377 Insecure Temporary File

## Description

Insecure Temporary File

Reference:
https://cwe.mitre.org/data/definitions/377.html


**OWASP Category**: A01:2021 – Broken Access Control


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// VULNERABLE: Predictable temp file name
File tempFile = new File("/tmp/myapp_" + userId + ".tmp");
tempFile.createNewFile();
```


**Why it's vulnerable:** This pattern is vulnerable to Insecure Temporary File




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// SECURE: Use Files.createTempFile with restrictive permissions
Path tempFile = Files.createTempFile("myapp_", ".tmp");
// Set restrictive permissions (owner only)
Set<PosixFilePermission> perms = EnumSet.of(
    PosixFilePermission.OWNER_READ,
    PosixFilePermission.OWNER_WRITE
);
Files.setPosixFilePermissions(tempFile, perms);
// Ensure cleanup
tempFile.toFile().deleteOnExit();
```


**Why it's secure:** Implements proper protection against Insecure Temporary File




---

## Detection Pattern

Look for these patterns in your codebase:


```bash
# Find temp file creation
grep -rn "createNewFile\\|File.*tmp" --include="*.java"
```



---

## Remediation Steps


1. Use Files.createTempFile() for random file names

2. Set restrictive file permissions

3. Use deleteOnExit() or try-with-resources

4. Consider using system temp directory


---

## Key Imports

```java

import java.nio.file.Files;

import java.nio.file.attribute.PosixFilePermission;

```

---

## Verification

After remediation:


- Run SAST scanner to confirm vulnerability is resolved

- Review all instances of the vulnerable pattern

- Add unit tests that verify the secure implementation

- Check for similar patterns in related code


---

## Trigger Examples

```
Fix CWE-377 vulnerability
Resolve Insecure Temporary File issue
Secure this Java code against insecure temporary file
SAST reports CWE-377
```

---

## Common Vulnerable Locations

| Layer | Files | Patterns |
|-------|-------|----------|

| Controller | `*Controller.java` | User input handling |

| Service | `*Service.java` | Business logic |

| Repository | `*Repository.java` | Data access |


---

## References


- [CWE-377: Insecure Temporary File](https://cwe.mitre.org/data/definitions/377.html)


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**Source**: Generated by [Java CWE Security Skills Generator](https://github.com/DevelopersCoffee/java-cwe-security-skills)
**Last Updated**: 2026-03-07