Skip to main content

Modernize and secure temp file creation

pixee:java/upgrade-tempfile-to-nio

ImportanceReview GuidanceRequires Scanning Tool
MEDIUMMerge Without ReviewNo

This change replaces the usage of java.io.File#createTempFile with java.nio.file.Files#createTempFile which has more secure attributes.

The java.io.File#createTempFile() method creates a file that is world-readable and world-writeable, which is almost never necessary. Also, the file created is placed in a predictable directory (e.g., /tmp). Having predictable file names, locations, and will lead to many types of vulnerabilities. History has shown that this insecure pattern can lead to information leakage, privilege escalation and even code execution.

Our changes look something like this:

+  import java.nio.file.Files;
...
- File txtFile = File.createTempFile("acme", ".txt");
+ File txtFile = Files.createTempFile("acme", ".txt").toFile();

References