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Jarrett's Tech Blog - Browsing BlogEngine.NET

Comments Security Hole in BlogEngine.NET 1.4
I found a hole in BlogEngine.NET that allows anyone to delete and approve comments.
UPDATE 7/11: Fixed in 1.4.0.12
Verify the Hole
- Add a test comment to your blog
- Refresh the blog posting to retrieve latest source
- View source of blog posting
- Find guid of comment to delete (see line 103 below)
```
<div id="id_9c2b8578-1dde-421e-94ff-5ea7e0d82012" class="comment">
  <p class="date">7/10/2008 4:13:35 PM</p>
  <p class="gravatar"><img src="http://www.gravatar.com/avatar/b642b4217b34b1e8d3bd915fc65c4452.jpg?s=80&amp;d=..." alt="Test3" /></p>
  <p class="content">asfasdfafdasd sa afsdfdsaas </p>
  <p class="author">
    Test3
    <img src="/blogengine/pics/flags/us.png" class="flag" alt="us" />
  </p>
</div>
```
- Request a POST to BlogPostUrl.aspx?deletecomment=guid
- Refresh the page and notice comment is deleted
Patch the Hole

You can patch the hole by updating the Page_Load event in the CommentView.ascx.cs file by checking for an authenticated user (lines 117,118, & 127)
```
protected void Page_Load(object sender, EventArgs e)
{
  if (Post == null)
    Response.Redirect(Utils.RelativeWebRoot);
  
  if (!Page.IsPostBack && !Page.IsCallback)
  {
    if (Page.User.Identity.IsAuthenticated)
    {
      if (Request.QueryString["deletecomment"] != null)
        DeleteComment();
      
      if (!string.IsNullOrEmpty(Request.QueryString["approvecomment"]))
        ApproveComment();

      if (!string.IsNullOrEmpty(Request.QueryString["approveallcomments"]))
        ApproveAllComments();
    }

  string path = Utils.RelativeWebRoot + "themes/" + BlogSettings.Instance.Theme + "/CommentView.ascx";
```
Repeat the steps given above to verify that the hole has been patched.

In the process of adding OpenID support to the comment system in BlogEngine.NET I found myself deep in a rabbit hole of refactoring. This comment security issue is just one of the things I've found during my journey. I've reported the issue on the BlogEngine.NET Issue Tracker. I think it is important to point out that the patch above is just a quick fix. The proper solution is to put authorization checks in the business layer (the BlogEngine.Core.Post business object in this case).
Posted by Jarrett on July 10 at 5:06 PM

Comments (1)

Add OpenID to BlogEngine.NET 1.4 Part 1

Update : there is no Part 2 as I switched to AtomSite for my blog engine.

Here is a guide on how to add OpenID support to BlogEngine.NET 1.4. This first blog post will detail how to use an OpenID account to login as an existing blog user via impersonation. I've used Andrew's blog post How to add OpenID support to BlogEngine.NET as a starting place.

Pros

Quick, minimum changes required
Retains support of blogging tools (such as Live Writer)
Easy to understand and backwards compatible

Cons

Not "true" OpenID integration
Accounts are maintained separately
Impersonation file is required

Step 1: Download latest release of dotnetopenid library

Step 2: Place DotNetOpenId.dll into Bin folder (if compiling BlogEngine.Web then add reference to project)

Step 3: Update Login.aspx page

<%@ Register Assembly="DotNetOpenId" Namespace="DotNetOpenId.RelyingParty" TagPrefix="RP" %>

Replace

<asp:Login ID="Login1" runat="server" class="loginbox" />

with

<RP:OpenIdLogin ID="OpenIdLogin1" runat="server" onloggedin="OpenIdLogin1_LoggedIn" />

Step 4: Update Login.aspx.cs code behind file

Replace

protected void Page_Load(object sender, EventArgs e) 
{ 
  if (Page.User.Identity.IsAuthenticated) 
  { 
    changepassword1.Visible = true; 
    changepassword1.ContinueButtonClick += new EventHandler(changepassword1_ContinueButtonClick); 
    lsLogout.Visible = true; 
    Login1.Visible = false; 
    Page.Title += Resources.labels.changePassword; 
  }  
  else 
  { 
    Login1.LoggedIn += new EventHandler(Login1_LoggedIn); 
    Login1.FindControl("username").Focus(); 
  } 
}

with

protected void Page_Load(object sender, EventArgs e) 
{ 
  if (Page.User.Identity.IsAuthenticated) 
  { 
    changepassword1.Visible = true; 
    changepassword1.ContinueButtonClick += new EventHandler(changepassword1_ContinueButtonClick); 
    lsLogout.Visible = true; 
    OpenIdLogin1.Visible = false; 
    Page.Title += Resources.labels.changePassword; 
  } 
}

Replace

void Login1_LoggedIn(object sender, EventArgs e) 
{ 
  if (!Roles.IsUserInRole(Login1.UserName, BlogEngine.Core.BlogSettings.Instance.AdministratorRole)) 
    Response.Redirect(BlogEngine.Core.Utils.RelativeWebRoot, true); 
}

with

protected void OpenIdLogin1_LoggedIn(object sender, DotNetOpenId.RelyingParty.OpenIdEventArgs e) 
{ 
  //don't allow login control to login, we will do that manually 
  e.Cancel = true; 
  //get impersonated user 
  string user = Impersonation.Impersonate(e.ClaimedIdentifier); 
  if (!Roles.IsUserInRole(user, BlogEngine.Core.BlogSettings.Instance.AdministratorRole)) 
    Response.Redirect(BlogEngine.Core.Utils.RelativeWebRoot, true); 
  else 
    FormsAuthentication.RedirectFromLoginPage(user, OpenIdLogin1.RememberMe); 
}

Step 5: Add Impersonation.xml file to App_Data folder

<impersonation> 
  <impersonate> 
    <id>http://jarrettv.myopenid.com/</id> 
    <user>Jarrett</user> 
  </impersonate> 
</impersonation>

Step 6: Add Impersonation.cs to BlogEngineCore project and compile

using System;
using System.Linq;
using System.Xml.Linq;
using System.Web;
using System.Web.Hosting;

namespace BlogEngine.Core
{
    public class Impersonation
    {
        public static string Impersonate(string id)
        {
            string user = id;
            string path = BlogSettings.Instance.StorageLocation + "impersonation.xml";
            
            if (!VirtualPathUtility.IsAppRelative(path))
                throw new ArgumentException("xmlFileName must be app-relative");

            string fullyQualifiedPath = VirtualPathUtility.Combine
                (VirtualPathUtility.AppendTrailingSlash
                (HttpRuntime.AppDomainAppVirtualPath), path);

            string actualPath = HostingEnvironment.MapPath(fullyQualifiedPath);

            XDocument xDoc = XDocument.Load(actualPath);
            user = xDoc.Element("impersonation").Elements("impersonate")
                .Where(x => x.Element("id").Value == id).Select(x => x.Element("user")).Single().Value;
            return user;
        }
    }
}

Step 7: Deploy following changed files

Login.aspx
Login.aspx.cs
\Bin\BlogEngine.Core.dll
\Bin\DotNetOpenId.dll
\App_Data\Impersonation.xml

In the next part, I will add OpenID support to the comment system.

Technorati Tags: openid,asp.net,c#,blogengine

Posted by Jarrett on July 05 at 8:26 PM

Comments (4)

jvance.com

.net, c#, asp.net, linq, htpc, woodworking

Jarrett's Tech Blog - Browsing BlogEngine.NET

Comments Security Hole in BlogEngine.NET 1.4

Verify the Hole

Patch the Hole

Add OpenID to BlogEngine.NET 1.4 Part 1

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