How to decode viewstate

Question

I need to see the contents of the viewstate of an asp.net page. I looked for a viewstate decoder, found Fridz Onion\'s ViewState Decoder but it asks for the url of a page to

Answer 1

This is somewhat "native" .NET way of converting ViewState from string into StateBag Code is below:

public static StateBag LoadViewState(string viewState)
    {
        System.Web.UI.Page converterPage = new System.Web.UI.Page();
        HiddenFieldPageStatePersister persister = new HiddenFieldPageStatePersister(new Page());
        Type utilClass = typeof(System.Web.UI.BaseParser).Assembly.GetType("System.Web.UI.Util");
        if (utilClass != null && persister != null)
        {
            MethodInfo method = utilClass.GetMethod("DeserializeWithAssert", BindingFlags.NonPublic | BindingFlags.Static);
            if (method != null)
            {
                PropertyInfo formatterProperty = persister.GetType().GetProperty("StateFormatter", BindingFlags.NonPublic | BindingFlags.Instance);
                if (formatterProperty != null)
                {
                    IStateFormatter formatter = (IStateFormatter)formatterProperty.GetValue(persister, null);
                    if (formatter != null)
                    {
                        FieldInfo pageField = formatter.GetType().GetField("_page", BindingFlags.NonPublic | BindingFlags.Instance);
                        if (pageField != null)
                        {
                            pageField.SetValue(formatter, null);
                            try
                            {
                                Pair pair = (Pair)method.Invoke(null, new object[] { formatter, viewState });
                                if (pair != null)
                                {
                                    MethodInfo loadViewState = converterPage.GetType().GetMethod("LoadViewStateRecursive", BindingFlags.Instance | BindingFlags.NonPublic);
                                    if (loadViewState != null)
                                    {
                                        FieldInfo postback = converterPage.GetType().GetField("_isCrossPagePostBack", BindingFlags.NonPublic | BindingFlags.Instance);
                                        if (postback != null)
                                        {
                                            postback.SetValue(converterPage, true);
                                        }
                                        FieldInfo namevalue = converterPage.GetType().GetField("_requestValueCollection", BindingFlags.NonPublic | BindingFlags.Instance);
                                        if (namevalue != null)
                                        {
                                            namevalue.SetValue(converterPage, new NameValueCollection());
                                        }
                                        loadViewState.Invoke(converterPage, new object[] { ((Pair)((Pair)pair.First).Second) });
                                        FieldInfo viewStateField = typeof(Control).GetField("_viewState", BindingFlags.NonPublic | BindingFlags.Instance);
                                        if (viewStateField != null)
                                        {
                                            return (StateBag)viewStateField.GetValue(converterPage);
                                        }
                                    }
                                }
                            }
                            catch (Exception ex)
                            {
                                if (ex != null)
                                {

                                }
                            }
                        }
                    }
                }
            }
        }
        return null;
    }