CSHARP.IO.TAINT.PATH : Tainted Path (C#)

Tainted data flows into a field annotated as [PathTrusted], or into a file path creation method.

Checks for this class use the CodeSonar C# taint analysis. See Taint Tracking for CodeSonar C# Warning Classes for more information on this analysis, including lists of the methods that CodeSonar automatically recognizes as relevant and information about specifying additional methods that CodeSonar should recognize as taint sources, sinks, or sanitizers.

Use configuration parameter CSHARP_ANALYSIS_ADVANCED_INJECTION to specify the level of checking to perform for this and other taint-related warning classes:

Properties

Example

using System;
using System.IO;
using System.Net;

namespace DocumentationExample
{
    class OtherInjectionExamples
    {

        static void Main(string[] args)
        {
            string input = GetUserInput();

            CommandInjectionExample(input);
            PathInjectionExample(input);
            UrlInjectionExample(input);
        }

        private static String GetUserInput()
        {

            return Console.ReadLine();

        }

        private static void CommandInjectionExample(String input)
        {
            try
            {
                System.Diagnostics.Process.Start("CMD.exe", input); // Command Injection (C#) warning issued here 
            } catch (Exception e)
            {
                Console.WriteLine("invalid command: " + e.Message);
            }


        }

        private static void PathInjectionExample(string input)
        {
            try
            {
                File.Delete(input);                                 // Tainted Path (C#) warning issued here 
            } catch (Exception e)
            {
                Console.WriteLine("unable to delete file: " + e.Message);
            }
        }

        private static void UrlInjectionExample(String input)
        {

            try
            {
                WebRequest request = WebRequest.Create(input);      // Tainted URL (C#) warning issued here 
                // ...
 
                WebResponse response = request.GetResponse();

                using (Stream dataStream = response.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(dataStream);
                    string responseFromServer = reader.ReadToEnd();
                    Console.WriteLine(responseFromServer);
                }

                response.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("request error: " + e.Message);
            }
        }
    }

}

Resolution

Verify that a security error actually corresponds to unconstrained information flow from source locations into sink locations. If this is the case, add a sanitizing algorithm to clean data before it flows into sinks, or use prepared statements for SQL queries rather than free queries built from string concatenation.

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.