Telerik Web UI Unrestricted File Upload (CVE-2014-2217)
Description
The Telerik UI for ASP.NET AJAX component contains a critical vulnerability in the RadAsyncUpload control that uses weak cryptographic keys to encrypt upload-related data. An attacker can exploit this weakness to decrypt and manipulate upload requests, enabling the upload of malicious files to the server. While remote code execution has not been definitively confirmed in all environments, the ability to upload arbitrary files creates a significant attack vector that could lead to complete system compromise depending on server configuration and file handling mechanisms.
Remediation
Take the following steps to remediate this vulnerability:
1. Upgrade immediately to the latest version of Telerik UI for ASP.NET AJAX from the official Telerik Release History page.
2. Configure custom encryption keys in your web.config file to replace the default weak keys. Add the following configuration with strong, randomly-generated keys:
<appSettings> <add key="Telerik.AsyncUpload.ConfigurationEncryptionKey" value="YOUR-STRONG-RANDOM-KEY" /> <add key="Telerik.Upload.ConfigurationHashKey" value="YOUR-STRONG-RANDOM-KEY" /> <add key="Telerik.Web.UI.DialogParametersEncryptionKey" value="YOUR-STRONG-RANDOM-KEY" /> </appSettings>
3. Implement file upload restrictions by configuring allowed file extensions and maximum file sizes in the RadAsyncUpload control settings.
4. Review and apply all security recommendations from the official RadAsyncUpload Security Guide, including disabling the control if not actively used.
5. Audit existing uploads for any suspicious or unauthorized files that may have been placed on the server prior to remediation.