ASP.NET Web Forms Security Considerations
- 10 minutes to read
This document details important security considerations when deploying an ASP.NET Web Forms Dashboard application.
Data Connection Security
The Web Dashboard needs data connection parameters to get data from certain data sources or to display existing dashboards (for instance, created in the WinForms Designer or in code):
- Users can create data sources based on predefined data connections in the UI, or you can add predefined data sources in code. For example, DashboardSqlDataSource and DashboardOlapDataSource can require a user name and password.
- The Web Dashboard control automatically checks whether dashboards contain data connection parameters. In this case, the dashboard does not load and an error message is displayed. In this case, remove all connection parameters from the dashboard definition and keep only the connection name.
The Web Dashboard control does not expose connection strings from Web.config when it operates in Designer mode. You need to use a data connection string provider to avoid data leaks and pass connection parameters safely. You can use a predefined data connection string provider or implement a custom one:
- Use the predefined provider
ConfigFileConnectionStringsProvider is a predefined implementation of a data connection string provider. This provider makes all connection strings in Web.config available and allows users to create new data sources based on connection strings from the configuration file.
Pass the ConfigFileConnectionStringsProvider instance as the ASPxDashboard.SetConnectionStringsProvider / DashboardConfigurator.SetConnectionStringsProvider method’s parameter to use this provider.
A code snippet for ASP.NET Web Forms (if you use the
ASPxDashboardControl‘s API):using DevExpress.DataAccess.Web; // ... ASPxDashboard1.SetConnectionStringsProvider(new ConfigFileConnectionStringsProvider());A code snippet for ASP.NET Web Forms (if you use the
DashboardConfigurator‘s API):- Implement a custom provider
- A custom data connection provider allows you to add custom logic. For example, you can read connection strings from a custom source or manage connection strings between users. To use a custom connection provider, implement the IDataSourceWizardConnectionStringsProvider interface and pass the new provider to the ASPxDashboard.SetConnectionStringsProvider / DashboardConfigurator.SetConnectionStringsProvider method call. See the following topic for details: Register Default Data Connections.
While not recommended, you can disable the connection parameter validation if you set the DashboardConfigurator.PassCredentials property to true. This property was introduced to prevent you from passing confidential information to the client. If this property is enabled, the dashboard is displayed regardless of user credential information. Once again, do not enable this property in production apps.
Database Security
Enable Custom SQL
The Data Source Wizard initially allows users to construct SQL queries only in the built-in Query Builder. Queries constructed in the Query Builder can be considered safe because they only contain a SELECT statement.
Users cannot edit SQL queries in the Query Builder (the default setting). Refer to the following article to enable SQL query editing using the UI: Custom SQL Queries. Custom SQL queries are validated before execution. Make certain to apply secure SQL validation to prevent harmful request execution.
We recommend that you utilize the access control functionality of your database management system to achieve the highest level of database security.
Restrict Access to Unauthorized Assemblies
You cannot load custom assemblies that can be referenced by Entity Framework data sources (DashboardEFDataSource) (the default setting).
To permit a user to load a specific assembly, handle the DashboardConfigurator.CustomAssemblyLoading event. An unauthorized attempt to load a custom assembly will result in a CustomAssemblyLoadingProhibitedException.
Restrict Access to External Data Resources
The Dashboard Control obtains data from resources stored on the disk or on the Internet. We recommend that you specify access settings for data resources (Excel, Extract, and JSON data sources).
You can read files from any directory by default. To protect your application, use the AccessSettings class to explicitly specify where data sources can be read from. To accomplish this, configure rules in the DataResources property to restrict file system access to specified folders. You can call the SetRules(IAccessRule[]) method when your application starts to specify rules before a dashboard control sets its rules. The SetRules(IAccessRule[]) method can be called only once at application startup. Otherwise, the method will raise an exception. Alternatively, you can use the TrySetRules(IAccessRule[]) method, which does not raise an exception.
Data Source Access Rights
These examples show how to configure the Dashboard control so that it loads data in a multi-user environment. You can identify a user in the current session and select which underlying data source is available for this user.
Database Schema Customization
A custom database schema provider allows you to restrict access to tables, views, stored procedures, and columns in the Query Builder based on specific conditions (such as user role or connection settings). For more information on database schema providers, refer to the following article: Implement a Custom Database Schema.
The following example implements a custom database schema provider for SQL Data Sources in ASP.NET Web Forms:
Dashboard Parameters Security
A user can obtain sensitive information from dashboard parameters. Encode parameter values wherever/whenever possible. Do not store sensitive/unencrypted information within dashboard parameters.
Working Mode Access Rights
The Web Dashboard can function as a designer or viewer. The following modes are available:
- Designer
- The Web Dashboard works as a designer and allows users to create, edit, and save dashboards. In this mode, the control loads the extensions required to design dashboards. Users can access the Data Source Wizard, preview underlying data, and modify dashboards from storage. Requests from the dashboard backend server can be sent to third-party resources. A user can also switch the control to
Viewermode. This is the default mode. - Viewer
- The Web Dashboard works as a viewer and displays dashboards to users. In this mode, the control also loads the extensions required to design dashboards. A user can switch the control to
Designermode as needs dictate. - ViewerOnly
- The Web Dashboard does not load extensions required to design dashboards. Users cannot switch to
DesignerorViewermodes on the client.
Warning
Working mode does not influence server settings. Initially, the server works at the ClientTrustLevel.Full trust level. Verify trust level and specify the actions a client can initiate on the server.
Set the Restricted mode to protect dashboards stored on a server.
Restricted mode affects the Web Dashboard in the following manner:
Only dashboards stored in dashboard storage can be processed on the client. Designer mode does not work.
Calling the IEditableDashboardStorage.AddDashboard and IDashboardStorage.SaveDashboard methods leads to an exception.
Information about data sources contained in a dashboard xml definition is not passed to the client when you request a dashboard XML file.
The available ways depend on the server-side API you use in your ASP.NET Web Forms application.
ASPxDashboard Control’s API
For Web Forms in default mode (ASPxDashboard control’s API is used), set working mode to ViewerOnly. This automatically sets the control to Restricted mode.
DashboardConfigurator API
For Web Forms that use DashboardConfigurator, Viewer and ViewerOnly modes do not influence the server. The server works at the ClientTrustLevel.Full trust level.
Use one of the following ways to prevent inadvertent or unauthorized modifications to dashboards stored on the server:
- Handle the DashboardConfigurator.VerifyClientTrustLevel event and set e.ClientTrustLevel to Restricted mode.
- Derive a custom dashboard controller from RestrictedDashboardController instead of
DashboardController.
Dashboard Access Rights
The Web Dashboard allows users to open, modify, and create new dashboards. If you want to specify different access rights for different users, do one of the following:
If you use another storage type, check the access rights when you handle the following events:
If you use custom dashboard storage (IDashboardStorage or IEditableDashboardStorage), add the verification in the implemented class. See the following examples that show how to implement multi-tenant dashboard architecture:
Use HTTP Handlers
For the ASP.NET Web Forms Dashboard control to work correctly when the UseDashboardConfigurator property is set to true, register the ASPxHttpHandlerModule in Web.config as a module for resource processing and as a handler for data processing.
The ASPxHttpHandlerModule is automatically registered in this file in the following cases:
When you create an application with the Web Forms Dashboard control using DevExpress project templates.
When you have the Web Dashboard in ASP.NET Web Forms markup and switch to the Design tab in Visual Studio.
You can register a new ASPxHttpHandlerModule that should process requests with the DXDD.axd path as a handler in two sections:
- system.web/httpHandlers
- system.webServer/handlers for IIS7 and newer versions in integrated mode
<system.web>
...
<httpHandlers>
...
<add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.v18.2, Version=18.2.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET,POST" path="DXDD.axd" validate="false" />
</httpHandlers>
</system.web>
<system.webServer>
...
<handlers>
...
<add type="DevExpress.Web.ASPxHttpHandlerModule, DevExpress.Web.v18.2, Version=18.2.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET,POST" path="DXDD.axd" name="WebDashboardHandler" preCondition="integratedMode" />
</handlers>
</system.webServer>
All users (including unauthorized users) can get access to a dashboard control handler (the default setting). To limit access, add authorization to a dashboard control handler and deny access for all unauthorized users.
<system.web>
...
<authorization>
<deny verbs="DXDD.axd" users="?" />
</authorization>
</system.web>
Content Security Policy
A Content Security Policy (CSP) is an additional layer of security built into most modern browsers. It allows the browser to recognize and mitigate certain types of risks, including Cross Site Scripting (XSS) and data injection attacks. These attacks include, but are not limited to, data theft, page spoofing, and malware distribution.
The CSP defines a list of policies/directives and initial values that specify which resources your site will allow/disallow.
To enable CSP, specify a Content-Security-Policy header or use the <meta> tag to explicitly define authorized functionality with CSP directives.
The following meta tag specifies minimum required directives for the DevExpress Web BI Dashboard:
<head>
<!--...-->
<meta http-equiv="Content-Security-Policy" content="default-src 'self';
img-src data: https: http:;
script-src 'self' 'unsafe-inline';
style-src 'self' 'unsafe-inline'; "/>
<!--...-->
</head>
default-src 'self';- Fallback for other fetch directives.
img-src data: https: http:;- Allows components to load specific images and document pages.
script-src 'self' 'unsafe-inline';- Allows only scripts loaded from the same source as the current page protected with CSP.
style-src 'self' 'unsafe-inline';- Allows the use of inline style elements.
In ASP.NET Web Forms applications, you can implement a nonce-based CSP to disallow inline style and script execution.
For more information on Content Security Policy, refer to the following topic: Content Security Policy in ASP.NET Web Forms Applications.
Prevent Cross-Site Request Forgery (CSRF)
Cross-site request forgery (also known as XSRF or CSRF) is a form of malicious website exploit wherein unauthorized commands are submitted from a trusted user. To prevent cross-site request forgery (CSRF) attacks on your web application, use a custom dashboard controller and apply anti-forgery request validation. Review the following example for implementation details:
Cache Security
When Web Dashboard executes data-related operations in client data processing mode, data from a data source can be cached. The Web Dashboard control uses a single cache. The use of separate DashboardConfigurator instances does not create separate caches. Create a custom parameter to specify a different cache for each user:
// Configure user-specific data caching
private void ASPxDashboard1_CustomParameters(object sender, CustomParametersWebEventArgs e) {
var userId = Session["CurrentUser"].GetHashCode();
e.Parameters.Add(new DevExpress.DataAccess.Parameter("UserId", typeof(string), userId));
}
See the following topic for more information: ASP.NET Web Forms Dashboard Control - Manage an In-Memory Data Cache.