Security-IoMethods.md

Pattern: Use of unsafe IO.* method

Issue: -

Description

Checks for the first argument to IO.read, IO.binread, IO.write, IO.binwrite, IO.foreach, and IO.readlines.

If argument starts with a pipe character ('|') and the receiver is the IO class, a subprocess is created in the same way as Kernel#open, and its output is returned. Kernel#open may allow unintentional command injection, which is the reason these IO methods are a security risk. Consider to use File.read to disable the behavior of subprocess invocation.

Safety

This rule is unsafe because false positive will occur if the variable passed as the first argument is a command that is not a file path.

Examples

# bad
IO.read(path)
IO.read('path')

# good
File.read(path)
File.read('path')
IO.read('| command') # Allow intentional command invocation.

Further Reading

• RuboCop - Security/IoMethods