Tag Archives: fiddler

[Tutorial] Using Fiddler to debug SAML tokens on Mobile Devices (Android)

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Use Case:

This guide will go over configuring Fiddler to intercept traffic from mobile devices for debugging purposes.  This scenario can be beneficial in tracing/debugging SAML tokens issued from your IdP for a mobile application to consume.  We will be able to validate all traffic flowing in/from the Android device.

Configuring/Setting up Fiddler:

  1. Grab the latest copy of Fiddler from their website for Windows (it is a free download)
    1. https://www.telerik.com/download/fiddlerDownload Fiddler
  2. Install Fiddler on your local machine
    1. Double click fiddlersetup.exe
      Run fiddlersetup
    2. Agree to the End User License Agreement
      Fiddler Install - Accept EULA
    3. Set the installation directory and click Install
      Fiddler Install - Destination Folder
    4. Close the setup wizard
      Fiddler Install - Close Installation
  3. Launch Fiddler
    Launch Fiddler - Windows 10
  4. Click Cancel if prompted about AppContainers
    Fiddler - AppContainer Configuration - Cancel
  5. With Fiddler open click on Tools -> Telerik Fiddler Options...
    Fiddler - Tools - Telerik Fiddler Options
  6. Click on the Connections tab and check Allow remote computers to connect

  7. You will receive a dialog box saying it will need to restart.  Click OK and close out of Fiddler
  8. Once you relaunch Fiddler, click on the down arrow (if shown) and hover over the Online icon

At this point, Fiddler is configured properly, let's shift over to your mobile device. We'll shift gears to configuring the Android device to push traffic to Fiddler.

Configuring an Android device
(Android v6.0.1 at the time of writing)

  1. Slide down the notifications drawer from the top of the screen and hit the Settings (gear) icon in the top right
  2. Select Wi-Fi under the Wireless and networks section
  3. Select the wireless network you are connected to and click Edit

  4. Scroll down and check Show advanced options

  5. Select the drop-down for Proxy and choose Manual

  6. Type in the IP address gathered from Fiddler for the Proxy host name and set the Proxy Port to 8888 and click Save
    1. Note: 8888 is the default port for Fiddler, the port can be found under Fiddler -> Telerik Fiddler Options -> Connections tab
  7. Next, open up your web browser and navigate to http://ipv4.fiddler:8888
    1. Note: This is a small webpage served by the Fiddler application to validate the proxy settings are correct.  Likewise, we will use this page in the next step for SSL decryption
  8. On the Fiddler Echo Service page, click on the You can download the FiddlerRoot Certificate link
    1. Note: This download Fiddler's root certificate to allow us to intercept SSL traffic for debugging purposes
  9. Once the certificate has downloaded, type Fiddler as the Certificate name and click OK

  10. Optional step: Open up your web browser and navigate to a website using SSL (I did https://google.com)
    1. Note: Here you can validate that the SSL certificate used is Fiddler's root certificate.  This is a good sign that we are intercepting the traffic

Turn off Fiddler from intercepting SSL traffic

Remove the proxy settings

  1. Slide down the notifications drawer from the top of the screen and hit the Settings (gear) icon in the top right
  2. Select Wi-Fi under the Wireless and networks section
  3. Select the wireless network you are connected to and click Edit

  4. Scroll down and check Show advanced options (you should see your old proxy settings unlike my screenshot below)

  5. Select the drop-down for Proxy and choose None

  6. Select Save
  7. At this point, you should be able to capture the traffic through the Fiddler application on your Windows machine; see the screenshot below showing traffic from the android device
    1. NOTE/TIP: If you turn off capturing, you will turn off capturing on Windows, but not for the mobile device.  This can help cut down on the "noise" in getting your sample/debug logs.

Remove the Fiddler SSL certificate

  1. Slide down the notifications drawer from the top of the screen and hit the Settings (gear) icon in the top right
  2. Select Security

  3. Select Trusted credentials

  4. Select the User tab on the Trusted credentials window
  5. Scroll down through the certificate information and towards the bottom you will see a Remove button; press the REMOVE button.
    1. Note: You have to scroll the text, there is no scrollbar until you start the scrolling gesture

 

[Tutorial] Using Fiddler to debug SAML tokens issued from ADFS

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Problem:

Many applications want to federate with leverage certain attributes like nameid (nameidentifier), but the problem is the format is wildly different from one application to another.  In this case, one application might use a unique value like an employee ID, another UPN, another email address, and so on.  Or maybe it isn't an attribute, but you are leveraging SHA1 as your signature hashing algorithm and the application is looking for MD5.

In this case, sometimes you may not be sure what you are sending to the application and are looking to the vendor to help you understand what you need to change in ADFS or if you are working on a custom application, need help debugging your claims rules to integrate into that application.  In this case, I will show you how to leverage Fiddler to acquire the SAML Tokens issued by ADFS to validate what attributes/values you are passing to the federate application.

Tutorial:

  1. Grab the latest copy of Fiddler from their website (it is a free download)
    1. https://www.telerik.com/download/fiddlerDownload Fiddler
  2. Install Fiddler on your local machine
    1. Double click fiddlersetup.exe
      Run fiddlersetup
    2. Agree to the End User License Agreement
      Fiddler Install - Accept EULA
    3. Set the installation directory and click Install
      Fiddler Install - Destination Folder
    4. Close the setup wizard
      Fiddler Install - Close Installation
  3. Launch Fiddler
    Launch Fiddler - Windows 10
  4. Click Cancel if prompted about AppContainers
    Fiddler - AppContainer Configuration - Cancel
  5. With Fiddler open click on Tools -> Telerik Fiddler Options...
    Fiddler - Tools - Telerik Fiddler Options
  6. Click on the HTTPS tab and check Decrypt HTTPS traffic and click OK
    1. Note: you may be prompted to trust a certificate.  You must trust the certificate so Fiddler can intercept your encrypted traffic and decrypt it.  Fiddler will not permanently capture traffic when the application is closed.
      Fiddler - Tools - Telerik Fiddler Options - HTTPS - Decrypt HTTPS traffic
  7. Close out of Fiddler
    Fiddler - Close
  8. Open Fiddler
    Launch Fiddler - Windows 10
  9. Open up Internet Explorer in one window and Fiddler side-by-side.  Drag the Crosshair icon onto Internet Explorer.  This will target only traffic in this process (browser window) to help filter down intercepted traffic.
    Fiddler - Process Selector - Drag Drop
  10. Select the X icon with a dropdown and click Remove all to clear your trace
    Fiddler - X - Remove All
  11. Go to the url of the federated application and login.  In this case, I am going to use https://outlook.com/owa/jackstromberg.com; once you have logged into the application or received the error to your application upon login, click File - Capture Traffic to stop the logs
    Fiddler - File - Capture Traffic - ADFS
  12. Within your logs, look for the last 200 response from your ADFS server before being redirected to your application (which will not show up as a 302, since we are posting to the new URL)
    Fiddler - HTTPS 200 - ADFS - SAML Post
  13. Click on the Inspectors tab, and select the Raw tab at the bottom and copy the value from the hidden input tag with the name of wresult
    Fiddler - Inspectors - Raw - wresult - encoded html
  14. Paste the encoded HTML into my HTML Encoder/Decoder in the Encoded text box and click Decode.
    1. Note: The encoder/decoder is all JavaScript based that functions client/side, so no data will leave your network.
      JackStromberg - HTML Encoder - Decoder - SAML
  15. Copy the Decoded HTML and paste it into an XML formatter of your choice.  Here I am using Bing:
    Bing - XML Formatter - SAML Token
  16. Copy the result into Notepad and you can now read the information
    Notepad - SAML Decoded - Formatted XML

Going into the claim and how it works is outside the scope of this tutorial, but as you can see in the last screenshot above we have the raw SAML token we will send to the relying party trust to consume.  At this point, the vendor can be involved to help troubleshoot any values or attributes that are in an incorrect format.