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Modernize and secure temp file creation


ImportanceReview GuidanceRequires Scanning Tool
MEDIUMMerge Without ReviewNo

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

The 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();