Need

To prevent errors and potential security issues caused by assigning the wrong type of value to a variable

Context

• Usage of Elixir for building scalable and fault-tolerant applications
• Usage of Elixir for building scalable and fault-tolerant applications
• Usage of dynamically typed language

Description

Non compliant code

        defmodule VulnerableCode do
  def add_one(input) do
    input + 1
  end
end
        
        

This Elixir code is vulnerable because it assigns a string to a variable that is expected to be a number. If a string is supplied instead of a number, an error will occur when trying to perform an arithmetic operation.

Steps

• Perform type checking before using the variable.
• Handle the error case when the value is not of the expected type.

Compliant code

        defmodule SecureCode do
  def add_one(input) when is_number(input) do
    input + 1
  end

  def add_one(_input) do
    {:error, "Input must be a number"}
  end
end
        
        

This Elixir code is safe because it checks the type of the input before performing the arithmetic operation. If the input is not a number, an error message is returned instead of causing a runtime error.

References

• 113. Improper type assignation