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

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Vulnerable Pattern

❌ Example 1: Vulnerable Pattern

// 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

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Deterministic Fix

✅ Secure Implementation: Secure Implementation

// 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

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Detection Pattern

Look for these patterns in your codebase:

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

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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

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Key Imports

import java.nio.file.Files;

import java.nio.file.attribute.PosixFilePermission;

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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

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Trigger Examples

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

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Common Vulnerable Locations

Layer	Files	Patterns

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

| Service | *Service.java | Business logic |

| Repository | *Repository.java | Data access |

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References

• CWE-377: Insecure Temporary File

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Source: Generated by Java CWE Security Skills Generator Last Updated: 2026-03-07