How to decode viewstate

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 get its viewstate. Since my viewstate is formed after a postback and comes as a result of an operation in an update panel, I cannot provide a url. I need to copy & paste the viewstate string and see what’s inside. Is there a tool or a website exist that can help viewing the contents of viewstate?

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Here’s an online ViewState decoder:

http://ignatu.co.uk/ViewStateDecoder.aspx

Edit: Unfortunatey, the above link is dead – here’s another ViewState decoder (from the comments):

http://viewstatedecoder.azurewebsites.net/

Method 2

Use Fiddler and grab the view state in the response and paste it into the bottom left text box then decode.

Method 3

Here is the source code for a ViewState visualizer from Scott Mitchell’s article on ViewState (25 pages)

using System;
using System.Collections;
using System.Text;
using System.IO;
using System.Web.UI;


namespace ViewStateArticle.ExtendedPageClasses
{
    /// <summary>
    /// Parses the view state, constructing a viaully-accessible object graph.
    /// </summary>
    public class ViewStateParser
    {
        // private member variables
        private TextWriter tw;
        private string indentString = "   ";

        #region Constructor
        /// <summary>
        /// Creates a new ViewStateParser instance, specifying the TextWriter to emit the output to.
        /// </summary>
        public ViewStateParser(TextWriter writer)
        {
            tw = writer;
        }
        #endregion

        #region Methods
        #region ParseViewStateGraph Methods
        /// <summary>
        /// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
        /// </summary>
        /// <param name="viewState">The view state object to start parsing at.</param>
        public virtual void ParseViewStateGraph(object viewState)
        {
            ParseViewStateGraph(viewState, 0, string.Empty);    
        }

        /// <summary>
        /// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
        /// </summary>
        /// <param name="viewStateAsString">A base-64 encoded representation of the view state to parse.</param>
        public virtual void ParseViewStateGraph(string viewStateAsString)
        {
            // First, deserialize the string into a Triplet
            LosFormatter los = new LosFormatter();
            object viewState = los.Deserialize(viewStateAsString);

            ParseViewStateGraph(viewState, 0, string.Empty);    
        }

        /// <summary>
        /// Recursively parses the view state.
        /// </summary>
        /// <param name="node">The current view state node.</param>
        /// <param name="depth">The "depth" of the view state tree.</param>
        /// <param name="label">A label to display in the emitted output next to the current node.</param>
        protected virtual void ParseViewStateGraph(object node, int depth, string label)
        {
            tw.Write(System.Environment.NewLine);

            if (node == null)
            {
                tw.Write(String.Concat(Indent(depth), label, "NODE IS NULL"));
            } 
            else if (node is Triplet)
            {
                tw.Write(String.Concat(Indent(depth), label, "TRIPLET"));
                ParseViewStateGraph(((Triplet) node).First, depth+1, "First: ");
                ParseViewStateGraph(((Triplet) node).Second, depth+1, "Second: ");
                ParseViewStateGraph(((Triplet) node).Third, depth+1, "Third: ");
            }
            else if (node is Pair)
            {
                tw.Write(String.Concat(Indent(depth), label, "PAIR"));
                ParseViewStateGraph(((Pair) node).First, depth+1, "First: ");
                ParseViewStateGraph(((Pair) node).Second, depth+1, "Second: ");
            }
            else if (node is ArrayList)
            {
                tw.Write(String.Concat(Indent(depth), label, "ARRAYLIST"));

                // display array values
                for (int i = 0; i < ((ArrayList) node).Count; i++)
                    ParseViewStateGraph(((ArrayList) node)[i], depth+1, String.Format("({0}) ", i));
            }
            else if (node.GetType().IsArray)
            {
                tw.Write(String.Concat(Indent(depth), label, "ARRAY "));
                tw.Write(String.Concat("(", node.GetType().ToString(), ")"));
                IEnumerator e = ((Array) node).GetEnumerator();
                int count = 0;
                while (e.MoveNext())
                    ParseViewStateGraph(e.Current, depth+1, String.Format("({0}) ", count++));
            }
            else if (node.GetType().IsPrimitive || node is string)
            {
                tw.Write(String.Concat(Indent(depth), label));
                tw.Write(node.ToString() + " (" + node.GetType().ToString() + ")");
            }
            else
            {
                tw.Write(String.Concat(Indent(depth), label, "OTHER - "));
                tw.Write(node.GetType().ToString());
            }
        }
        #endregion

        /// <summary>
        /// Returns a string containing the <see cref="IndentString"/> property value a specified number of times.
        /// </summary>
        /// <param name="depth">The number of times to repeat the <see cref="IndentString"/> property.</param>
        /// <returns>A string containing the <see cref="IndentString"/> property value a specified number of times.</returns>
        protected virtual string Indent(int depth)
        {
            StringBuilder sb = new StringBuilder(IndentString.Length * depth);
            for (int i = 0; i < depth; i++)
                sb.Append(IndentString);

            return sb.ToString();
        }
        #endregion

        #region Properties
        /// <summary>
        /// Specifies the indentation to use for each level when displaying the object graph.
        /// </summary>
        /// <value>A string value; the default is three blank spaces.</value>
        public string IndentString
        {
            get
            {
                return indentString;
            }
            set
            {
                indentString = value;
            }
        }
        #endregion
    }
}

And here’s a simple page to read the viewstate from a textbox and graph it using the above code
private void btnParse_Click(object sender, System.EventArgs e)
        {
            // parse the viewState
            StringWriter writer = new StringWriter();
            ViewStateParser p = new ViewStateParser(writer);

            p.ParseViewStateGraph(txtViewState.Text);
            ltlViewState.Text = writer.ToString();
        }

Method 4

As another person just mentioned, it’s a base64 encoded string. In the past, I’ve used this website to decode it:

http://www.motobit.com/util/base64-decoder-encoder.asp

Method 5

Here’s another decoder that works well as of 2014: http://viewstatedecoder.azurewebsites.net/

This worked on an input on which the Ignatu decoder failed with “The serialized data is invalid” (although it leaves the BinaryFormatter-serialized data undecoded, showing only its length).

Method 6

JavaScript-ViewState-Parser:

The parser should work with most non-encrypted ViewStates. It doesn’t
handle the serialization format used by .NET version 1 because that
version is sorely outdated and therefore too unlikely to be
encountered in any real situation.

http://deadliestwebattacks.com/2011/05/29/javascript-viewstate-parser/


Parsing .NET ViewState


Method 7

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;
    }

Method 8

You can ignore the URL field and simply paste the viewstate into the Viewstate string box.

It does look like you have an old version; the serialisation methods changed in ASP.NET 2.0, so grab the 2.0 version

Method 9

Best way in python is use this link.

A small Python 3.5+ library for decoding ASP.NET viewstate.

First install that: pip install viewstate

>>> from viewstate import ViewState
>>> base64_encoded_viewstate = '/wEPBQVhYmNkZQ9nAgE='
>>> vs = ViewState(base64_encoded_viewstate)
>>> vs.decode()
('abcde', (True, 1))

Method 10

Online Viewstate Viewer made by Lachlan Keown:

http://lachlankeown.blogspot.com/2008/05/online-viewstate-viewer-decoder.html

Method 11

Normally, ViewState should be decryptable if you have the machine-key, right? After all, ASP.net needs to decrypt it, and that is certainly not a black box.


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

0 0 votes
Article Rating
Subscribe
Notify of
guest

0 Comments
Inline Feedbacks
View all comments
0
Would love your thoughts, please comment.x
()
x