Arbitrary Code Execution for C#

CodeEval.cs

using System;
using System.CodeDom.Compiler;
using System.Reflection;
using System.Threading.Tasks;

/*
    To execute, run
    string code = "your code here";
    if (!code.Contains("return")) code = "return " + code;
    code = code.Trim().TrimEnd(';') + ";";
    var result = await new CodeEval().CSharp(code);
*/

namespace Program
{
    public class CodeEval
    {
        public async Task<string> CSharp(string code)
        {
            string result = "";
            try{


                CodeDomProvider evaluator = CodeDomProvider.CreateProvider("CSharp");
                CompilerParameters parameters = new CompilerParameters();

                parameters.ReferencedAssemblies.Add("System.dll");
                parameters.ReferencedAssemblies.Add("System.Runtime.dll");
                parameters.ReferencedAssemblies.Add("System.Linq.dll");
                parameters.ReferencedAssemblies.Add("System.Threading.Tasks.dll");
                parameters.ReferencedAssemblies.Add("System.Interactive.Async.dll");
                parameters.ReferencedAssemblies.Add("System.Collections.Immutable.dll");
                parameters.CompilerOptions = "/t:library";
                parameters.GenerateInMemory = true;

                string classCode = "using System;\n" +
                    "using System.Runtime;\n" +
                    "using System.Threading.Tasks;\n" +
                    "using System.Collections;\n" +
                    "using System.Collections.Generic;\n" +
                    "using System.Text.RegularExpressions;\n" +
                    "using System.Linq;\n\n" +
                    "namespace CodeEvaluator\n" +
                    "{\n" +
                        "public class CodeEvaluator\n" +
                        "{\n" +
                            "public async Task<object> EvalCode()\n" +
                            "{\n" +
                                "try\n" +
                                "{\n" + 
                                    code +
                                "}\n" +
                                "catch(Exception exception)\n" +
                                "{\n" +
                                    "return exception.Message;\n" +
                                "}\n" +
                            "}\n" +
                        "}\n" +
                    "}";
                CompilerResults codeResults = evaluator.CompileAssemblyFromSource(parameters, classCode);

                if (codeResults.Errors.Count > 0)
                {
                    return codeResults.Errors[0].ErrorText;
                }

                if (!string.IsNullOrEmpty(result))
                    return result;
                Assembly assembly = codeResults.CompiledAssembly;
                object instance = assembly.CreateInstance("CodeEvaluator.CodeEvaluator");
                if (instance == null)
                    return (string) null;
                MethodInfo method = instance.GetType().GetMethod("EvalCode");
                object returnedObject = await (Task<object>) method.Invoke(instance);
                result = returnedObject == null ? (string) null : returnedObject.ToString();
                evaluator.Dispose();
            }
            catch (Exception ex)
            {
                result = ex.Message;
            }
            return result;
        }
    }
}

CodeEvalWithObject.cs

using System;
using System.CodeDom.Compiler;
using System.Reflection;
using System.Threading.Tasks;

/*
    To execute, run
    string code = "your code here";
    if (!code.Contains("return")) code = "return " + code;
    code = code.Trim().TrimEnd(';') + ";";
    var result = await new CodeEval().CSharp(code);
*/

namespace Program
{
    public class CodeEval
    {
        public async Task<string> CSharp(string code, object obj)
        {
            string result = "";
            try{


                CodeDomProvider evaluator = CodeDomProvider.CreateProvider("CSharp");
                CompilerParameters parameters = new CompilerParameters();

                parameters.ReferencedAssemblies.Add("System.dll");
                parameters.ReferencedAssemblies.Add("System.Runtime.dll");
                parameters.ReferencedAssemblies.Add("System.Linq.dll");
                parameters.ReferencedAssemblies.Add("System.Threading.Tasks.dll");
                parameters.ReferencedAssemblies.Add("System.Interactive.Async.dll");
                parameters.ReferencedAssemblies.Add("System.Collections.Immutable.dll");
                parameters.CompilerOptions = "/t:library";
                parameters.GenerateInMemory = true;

                string classCode = "using System;\n" +
                    "using System.Runtime;\n" +
                    "using System.Threading.Tasks;\n" +
                    "using System.Collections;\n" +
                    "using System.Collections.Generic;\n" +
                    "using System.Text.RegularExpressions;\n" +
                    "using System.Linq;\n\n" +
                    "namespace CodeEvaluator\n" +
                    "{\n" +
                        "public class CodeEvaluator\n" +
                        "{\n" +
                            "public async Task<object> EvalCode(object obj)\n" +
                            "{\n" +
                                "try\n" +
                                "{\n" + 
                                    code +
                                "}\n" +
                                "catch(Exception exception)\n" +
                                "{\n" +
                                    "return exception.Message;\n" +
                                "}\n" +
                            "}\n" +
                        "}\n" +
                    "}";
                CompilerResults codeResults = evaluator.CompileAssemblyFromSource(parameters, classCode);

                if (codeResults.Errors.Count > 0)
                {
                    return codeResults.Errors[0].ErrorText;
                }

                if (!string.IsNullOrEmpty(result))
                    return result;
                Assembly assembly = codeResults.CompiledAssembly;
                object instance = assembly.CreateInstance("CodeEvaluator.CodeEvaluator");
                if (instance == null)
                    return (string) null;
                MethodInfo method = instance.GetType().GetMethod("EvalCode");
                object returnedObject = await (Task<object>) method.Invoke(instance, new object[1]
                {
                    (object) obj
                });
                result = returnedObject == null ? (string) null : returnedObject.ToString();
                evaluator.Dispose();
            }
            catch (Exception ex)
            {
                result = ex.Message;
            }
            return result;
        }
    }
}