Having trouble decrypting HTTPS traffic from IOS using FiddlerCore

1 posts, 0 answers
  1. Red
    Red avatar
    1 posts
    Member since:
    Nov 2017

    Posted 19 Nov 2017 Link to this post

    I was able to run the FiddlerCore demo (that comes with the package) without issue. I see both http and https traffic being logged on my PC.
    My goal now is to do the same for my iOS traffic but I can't figure out what I am missing. I can see my https traffic fine when I use the desktop Fiddler app, by following the instructions at ConfigureForiOS.

    I run the console FiddlerCore demo, hit 't' to trust the root certificate and then try to follow the same steps on my iPhone as I did for the Fidder app, namely setting my proxy to the Fiddler instance (my machine's IP and port 7777 as that is what it looks like the demo is using) and trusting the Fiddler cert that I had already installed on my phone when setting it up to work with the desktop Fiddler app. Then when I try to start an app on my phone that goes over https (for example a game) it just hangs. I don't see any errors being logged in the console app. It works ok when just running the desktop Fiddler app.
    My SSL/cert/Fiddler knowledge is weak so I am hoping I am just missing a simple step or two.  Do I have to somehow copy the root certificate that the demo creates over to my phone?  I thought the one already installed when using the Fiddler desktop app would suffice.

     

    Questions:
    How can I capture iOS HTTPS traffic using the FiddlerCore demo app?
    Do I need to trust the root certificate each time I start the demo app (hitting 't')?

     

    Thanks.

    P.S. I added the demo app here, which can be found in the FiddlerCore package, for reference.

     

    using Fiddler;
    using System;
    using System.Collections.Generic;
    using System.Threading;
     
    namespace FiddlerCoreDemo
    {
      class Program
      {
        static Proxy oSecureEndpoint;
        static string sSecureEndpointHostname = "localhost";
        static int iSecureEndpointPort = 7777;
     
        public static void WriteCommandResponse(string s)
        {
          ConsoleColor oldColor = Console.ForegroundColor;
          Console.ForegroundColor = ConsoleColor.Yellow;
          Console.WriteLine(s);
          Console.ForegroundColor = oldColor;
        }
     
        public static void DoQuit()
        {
          WriteCommandResponse("Shutting down...");
          if (null != oSecureEndpoint) oSecureEndpoint.Dispose();
          Fiddler.FiddlerApplication.Shutdown();
          Thread.Sleep(500);
        }
        private static string Ellipsize(string s, int iLen)
        {
          if (s.Length <= iLen) return s;
          return s.Substring(0, iLen - 3) + "...";
        }
     
    #if SAZ_SUPPORT
            private static void ReadSessions(List<Fiddler.Session> oAllSessions)
            {
                Session[] oLoaded = Utilities.ReadSessionArchive(Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
                                                               + Path.DirectorySeparatorChar + "ToLoad.saz", false);
     
                if ((oLoaded != null) && (oLoaded.Length > 0))
                {
                    oAllSessions.AddRange(oLoaded);
                    WriteCommandResponse("Loaded: " + oLoaded.Length + " sessions.");
                }
            }
     
            private static void SaveSessionsToDesktop(List<Fiddler.Session> oAllSessions)
            {
                bool bSuccess = false;
                string sFilename = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory)
                                 + Path.DirectorySeparatorChar + DateTime.Now.ToString("hh-mm-ss") + ".saz";
                try
                {
                    try
                    {
                        Monitor.Enter(oAllSessions);
     
                        string sPassword = null;
                        Console.WriteLine("Password Protect this Archive (Y/N)?");
                        ConsoleKeyInfo oCKI = Console.ReadKey();
                        if ((oCKI.KeyChar == 'y') || (oCKI.KeyChar == 'Y'))
                        {
                            Console.WriteLine("\nEnter the password:");
                            sPassword = Console.ReadLine();
                            Console.WriteLine(String.Format("\nEncrypting with Password: '{0}'", sPassword));
                        }
                        Console.WriteLine();
     
                        bSuccess = Utilities.WriteSessionArchive(sFilename, oAllSessions.ToArray(), sPassword, false);
                    }
                    finally
                    {
                        Monitor.Exit(oAllSessions);
                    }
     
                    WriteCommandResponse( bSuccess ? ("Wrote: " + sFilename) : ("Failed to save: " + sFilename) );
                }
                catch (Exception eX)
                {
                    Console.WriteLine("Save failed: " + eX.Message);
                }
            }
    #endif
     
        private static void WriteSessionList(List<Fiddler.Session> oAllSessions)
        {
          ConsoleColor oldColor = Console.ForegroundColor;
          Console.ForegroundColor = ConsoleColor.White;
          Console.WriteLine("Session list contains...");
          try
          {
            Monitor.Enter(oAllSessions);
            foreach (Session oS in oAllSessions)
            {
              Console.Write(String.Format("{0} {1} {2}\n{3} {4}\n\n", oS.id, oS.oRequest.headers.HTTPMethod, Ellipsize(oS.fullUrl, 60), oS.responseCode, oS.oResponse.MIMEType));
            }
          }
          finally
          {
            Monitor.Exit(oAllSessions);
          }
          Console.WriteLine();
          Console.ForegroundColor = oldColor;
        }
     
        static void Main(string[] args)
        {
          List<Fiddler.Session> oAllSessions = new List<Fiddler.Session>();
     
          // <-- Personalize for your Application, 64 chars or fewer
          Fiddler.FiddlerApplication.SetAppDisplayName("FiddlerCoreDemoApp");
     
          #region AttachEventListeners
          //
          // It is important to understand that FiddlerCore calls event handlers on session-handling
          // background threads.  If you need to properly synchronize to the UI-thread (say, because
          // you're adding the sessions to a list view) you must call .Invoke on a delegate on the
          // window handle.
          //
          // If you are writing to a non-threadsafe data structure (e.g. List<t>) you must
          // use a Monitor or other mechanism to ensure safety.
          //
     
          // Simply echo notifications to the console.  Because Fiddler.CONFIG.QuietMode=true
          // by default, we must handle notifying the user ourselves.
          Fiddler.FiddlerApplication.OnNotification += delegate (object sender, NotificationEventArgs oNEA) { Console.WriteLine("** NotifyUser: " + oNEA.NotifyString); };
          Fiddler.FiddlerApplication.Log.OnLogString += delegate (object sender, LogEventArgs oLEA) { Console.WriteLine("** LogString: " + oLEA.LogString); };
     
          Fiddler.FiddlerApplication.BeforeRequest += delegate (Fiddler.Session oS)
          {
            // Console.WriteLine("Before request for:\t" + oS.fullUrl);
            // In order to enable response tampering, buffering mode MUST
            // be enabled; this allows FiddlerCore to permit modification of
            // the response in the BeforeResponse handler rather than streaming
            // the response to the client as the response comes in.
            oS.bBufferResponse = false;
            Monitor.Enter(oAllSessions);
            oAllSessions.Add(oS);
            Monitor.Exit(oAllSessions);
     
            // Set this property if you want FiddlerCore to automatically authenticate by
            // answering Digest/Negotiate/NTLM/Kerberos challenges itself
            // oS["X-AutoAuth"] = "(default)";
     
            /* If the request is going to our secure endpoint, we'll echo back the response.
     
            Note: This BeforeRequest is getting called for both our main proxy tunnel AND our secure endpoint,
            so we have to look at which Fiddler port the client connected to (pipeClient.LocalPort) to determine whether this request
            was sent to secure endpoint, or was merely sent to the main proxy tunnel (e.g. a CONNECT) in order to *reach* the secure endpoint.
     
            As a result of this, if you run the demo and visit https://localhost:7777 in your browser, you'll see
     
            Session list contains...
     
                1 CONNECT http://localhost:7777
                200                                         <-- CONNECT tunnel sent to the main proxy tunnel, port 8877
     
                2 GET https://localhost:7777/
                200 text/html                               <-- GET request decrypted on the main proxy tunnel, port 8877
     
                3 GET https://localhost:7777/              
                200 text/html                               <-- GET request received by the secure endpoint, port 7777
            */
     
            if ((oS.oRequest.pipeClient.LocalPort == iSecureEndpointPort) && (oS.hostname == sSecureEndpointHostname))
            {
              oS.utilCreateResponseAndBypassServer();
              oS.oResponse.headers.SetStatus(200, "Ok");
              oS.oResponse["Content-Type"] = "text/html; charset=UTF-8";
              oS.oResponse["Cache-Control"] = "private, max-age=0";
              oS.utilSetResponseBody("<html><body>Request for httpS://" + sSecureEndpointHostname + ":" + iSecureEndpointPort.ToString() + " received. Your request was:<br /><plaintext>" + oS.oRequest.headers.ToString());
            }
          };
     
          /*
              // The following event allows you to examine every response buffer read by Fiddler. Note that this isn't useful for the vast majority of
              // applications because the raw buffer is nearly useless; it's not decompressed, it includes both headers and body bytes, etc.
              //
              // This event is only useful for a handful of applications which need access to a raw, unprocessed byte-stream
              Fiddler.FiddlerApplication.OnReadResponseBuffer += new EventHandler<RawReadEventArgs>(FiddlerApplication_OnReadResponseBuffer);
          */
     
          /*
          Fiddler.FiddlerApplication.BeforeResponse += delegate(Fiddler.Session oS) {
              // Console.WriteLine("{0}:HTTP {1} for {2}", oS.id, oS.responseCode, oS.fullUrl);
     
              // Uncomment the following two statements to decompress/unchunk the
              // HTTP response and subsequently modify any HTTP responses to replace
              // instances of the word "Microsoft" with "Bayden". You MUST also
              // set bBufferResponse = true inside the beforeREQUEST method above.
              //
              //oS.utilDecodeResponse(); oS.utilReplaceInResponse("Microsoft", "Bayden");
          };*/
     
          Fiddler.FiddlerApplication.AfterSessionComplete += delegate (Fiddler.Session oS)
          {
            //Console.WriteLine("Finished session:\t" + oS.fullUrl);
            Console.Title = ("Session list contains: " + oAllSessions.Count.ToString() + " sessions");
          };
     
          // Tell the system console to handle CTRL+C by calling our method that
          // gracefully shuts down the FiddlerCore.
          //
          // Note, this doesn't handle the case where the user closes the window with the close button.
          //
          Console.CancelKeyPress += new ConsoleCancelEventHandler(Console_CancelKeyPress);
          #endregion AttachEventListeners
     
          string sSAZInfo = "NoSAZ";
    #if SAZ_SUPPORT
                sSAZInfo = Assembly.GetAssembly(typeof(Ionic.Zip.ZipFile)).FullName;
     
                // You can load Transcoders from any different assembly if you'd like, using the ImportTranscoders(string AssemblyPath)
                // overload.
                //
                //if (!FiddlerApplication.oTranscoders.ImportTranscoders(Assembly.GetExecutingAssembly()))
                //{
                //    Console.WriteLine("This assembly was not compiled with a SAZ-exporter");
                //}
     
                DNZSAZProvider.fnObtainPwd = () =>
                {
                    Console.WriteLine("Enter the password (or just hit Enter to cancel):");
                    string sResult = Console.ReadLine();
                    Console.WriteLine();
                    return sResult;
                };
     
                FiddlerApplication.oSAZProvider = new DNZSAZProvider();
    #endif
     
          Console.WriteLine(String.Format("Starting {0} ({1})...", Fiddler.FiddlerApplication.GetVersionString(), sSAZInfo));
     
          // For the purposes of this demo, we'll forbid connections to HTTPS
          // sites that use invalid certificates. Change this from the default only
          // if you know EXACTLY what that implies.
          Fiddler.CONFIG.IgnoreServerCertErrors = false;
     
          // ... but you can allow a specific (even invalid) certificate by implementing and assigning a callback...
          // FiddlerApplication.OnValidateServerCertificate += new System.EventHandler<ValidateServerCertificateEventArgs>(CheckCert);
     
          FiddlerApplication.Prefs.SetBoolPref("fiddler.network.streaming.abortifclientaborts", true);
     
          // For forward-compatibility with updated FiddlerCore libraries, it is strongly recommended that you
          // start with the DEFAULT options and manually disable specific unwanted options.
          FiddlerCoreStartupFlags oFCSF = FiddlerCoreStartupFlags.Default;
     
          // E.g. If you want to add a flag, start with the .Default and "OR" the new flag on:
          // oFCSF = (oFCSF | FiddlerCoreStartupFlags.CaptureFTP);
     
          // ... or if you don't want a flag in the defaults, "and not" it out:
          // Uncomment the next line if you don't want FiddlerCore to act as the system proxy
          // oFCSF = (oFCSF & ~FiddlerCoreStartupFlags.RegisterAsSystemProxy);
     
          // *******************************
          // Important HTTPS Decryption Info
          // *******************************
          // When FiddlerCoreStartupFlags.DecryptSSL is enabled, you must include either
          //
          //     MakeCert.exe
          //
          // *or*
          //
          //     CertMaker.dll
          //     BCMakeCert.dll
          //
          // ... in the folder where your executable and FiddlerCore.dll live. These files
          // are needed to generate the self-signed certificates used to man-in-the-middle
          // secure traffic. MakeCert.exe uses Windows APIs to generate certificates which
          // are stored in the user's \Personal\ Certificates store. These certificates are
          // NOT compatible with iOS devices which require specific fields in the certificate
          // which are not set by MakeCert.exe.
          //
          // In contrast, CertMaker.dll uses the BouncyCastle C# library (BCMakeCert.dll) to
          // generate new certificates from scratch. These certificates are stored in memory
          // only, and are compatible with iOS devices.
     
          // Uncomment the next line if you don't want to decrypt SSL traffic.
          // oFCSF = (oFCSF & ~FiddlerCoreStartupFlags.DecryptSSL);
     
          // NOTE: In the next line, you can pass 0 for the port (instead of 8877) to have FiddlerCore auto-select an available port
          int iPort = 8877;
          Fiddler.FiddlerApplication.Startup(iPort, oFCSF);
     
          FiddlerApplication.Log.LogFormat("Created endpoint listening on port {0}", iPort);
     
          FiddlerApplication.Log.LogFormat("Starting with settings: [{0}]", oFCSF);
          FiddlerApplication.Log.LogFormat("Gateway: {0}", CONFIG.UpstreamGateway.ToString());
     
          Console.WriteLine("Hit CTRL+C to end session.");
     
          // We'll also create a HTTPS listener, useful for when FiddlerCore is masquerading as a HTTPS server
          // instead of acting as a normal CERN-style proxy server.
          oSecureEndpoint = FiddlerApplication.CreateProxyEndpoint(iSecureEndpointPort, true, sSecureEndpointHostname);
          if (null != oSecureEndpoint)
          {
            FiddlerApplication.Log.LogFormat("Created secure endpoint listening on port {0}, using a HTTPS certificate for '{1}'", iSecureEndpointPort, sSecureEndpointHostname);
          }
     
          bool bDone = false;
          do
          {
            Console.WriteLine("\nEnter a command [C=Clear; L=List; G=Collect Garbage; W=write SAZ; R=read SAZ;\n\tS=Toggle Forgetful Streaming; T=Trust Root Certificate; Q=Quit]:");
            Console.Write(">");
            ConsoleKeyInfo cki = Console.ReadKey();
            Console.WriteLine();
            switch (Char.ToLower(cki.KeyChar))
            {
              case 'c':
                Monitor.Enter(oAllSessions);
                oAllSessions.Clear();
                Monitor.Exit(oAllSessions);
                WriteCommandResponse("Clear...");
                FiddlerApplication.Log.LogString("Cleared session list.");
                break;
     
              case 'd':
                FiddlerApplication.Log.LogString("FiddlerApplication::Shutdown.");
                FiddlerApplication.Shutdown();
                break;
     
              case 'l':
                WriteSessionList(oAllSessions);
                break;
     
              case 'g':
                Console.WriteLine("Working Set:\t" + Environment.WorkingSet.ToString("n0"));
                Console.WriteLine("Begin GC...");
                GC.Collect();
                Console.WriteLine("GC Done.\nWorking Set:\t" + Environment.WorkingSet.ToString("n0"));
                break;
     
              case 'q':
                bDone = true;
                DoQuit();
                break;
     
              case 'r':
    #if SAZ_SUPPORT
                            ReadSessions(oAllSessions);
    #else
                WriteCommandResponse("This demo was compiled without SAZ_SUPPORT defined");
    #endif
                break;
     
              case 'w':
    #if SAZ_SUPPORT
                            if (oAllSessions.Count > 0)
                            {
                                SaveSessionsToDesktop(oAllSessions);
                            }
                            else
                            {
                                WriteCommandResponse("No sessions have been captured");
                            }
    #else
                WriteCommandResponse("This demo was compiled without SAZ_SUPPORT defined");
    #endif
                break;
     
              case 't':
                try
                {
                  WriteCommandResponse("Result: " + Fiddler.CertMaker.trustRootCert().ToString());
                }
                catch (Exception eX)
                {
                  WriteCommandResponse("Failed: " + eX.ToString());
                }
                break;
     
              // Forgetful streaming
              case 's':
                bool bForgetful = !FiddlerApplication.Prefs.GetBoolPref("fiddler.network.streaming.ForgetStreamedData", false);
                FiddlerApplication.Prefs.SetBoolPref("fiddler.network.streaming.ForgetStreamedData", bForgetful);
                Console.WriteLine(bForgetful ? "FiddlerCore will immediately dump streaming response data." : "FiddlerCore will keep a copy of streamed response data.");
                break;
     
            }
          } while (!bDone);
        }
     
        /*
        /// <summary>
        /// This callback allows your code to evaluate the certificate for a site and optionally override default validation behavior for that certificate.
        /// You should not implement this method unless you understand why it is a security risk.
        /// </summary>
        static void CheckCert(object sender, ValidateServerCertificateEventArgs e)
        {
            if (null != e.ServerCertificate)
            {
                Console.WriteLine("Certificate for " + e.ExpectedCN + " was for site " + e.ServerCertificate.Subject + " and errors were " + e.CertificatePolicyErrors.ToString());
     
                if (e.ServerCertificate.Subject.Contains("fiddler2.com"))
                {
                    Console.WriteLine("Got a certificate for fiddler2.com. We'll say this is also good for any other site, like https://fiddlertool.com.");
                    e.ValidityState = CertificateValidity.ForceValid;
                }
            }
        }
        */
     
        /*
        // This event handler is called on every socket read for the HTTP Response. You almost certainly don't want
        // to add a handler for this event, but the code below shows how you can use it to mess up your HTTP traffic.
        static void FiddlerApplication_OnReadResponseBuffer(object sender, RawReadEventArgs e)
        {
            // NOTE: arrDataBuffer is a fixed-size array. Only bytes 0 to iCountOfBytes should be read/manipulated.
            //
            // Just for kicks, lowercase every byte. Note that this will obviously break any binary content.
            for (int i = 0; i < e.iCountOfBytes; i++)
            {
                if ((e.arrDataBuffer[i] > 0x40) && (e.arrDataBuffer[i] < 0x5b))
                {
                    e.arrDataBuffer[i] = (byte)(e.arrDataBuffer[i] + (byte)0x20);
                }
            }
            Console.WriteLine(String.Format("Read {0} response bytes for session {1}", e.iCountOfBytes, e.sessionOwner.id));
        }
        */
     
        /// <summary>
        /// When the user hits CTRL+C, this event fires.  We use this to shut down and unregister our FiddlerCore.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        static void Console_CancelKeyPress(object sender, ConsoleCancelEventArgs e)
        {
          DoQuit();
        }
      }
    }

     

Back to Top