Getting '/RDWeb/Pages/en-US/login.aspx' does not exist exceptions continuously in Azure App service

Question

We have an ASP.NET MVC application hosted in Azure App Services. After a few days of deployment, we are continuously getting an error added below.

We do not have any path /RDWeb/Pages/en-US/login.aspx in our application as mentioned in the error and no other related applications can call the route of this application.

Exception message: The file '/RDWeb/Pages/en-US/login.aspx' does not exist.

We are still unsure about the cause of this error we are experiencing. We are getting lots of error logs for this exception in the application insights (daily ~1k).

We need to know why this exception is occurring continuously in the app hosted in Azure App service.

Answer 1

@Sadiq Shifath The error message you're seeing, '/RDWeb/Pages/en-US/login.aspx' does not exist, is my best guess due to automated bots or crawlers attempting to access paths that are commonly associated with Remote Desktop Web Access (RDWeb) services. Here are a few steps you can take to address this issue:

1. Ignore the Requests. Since these requests are not relevant to your application, you can configure your application to ignore them. This can be done by adding a custom error page or a specific route handler that returns a 404 status code for these paths.
2. Block the Requests. Use web application firewall (WAF) rules or IP restrictions to block these requests. Azure Application Gateway WAF or Azure Front Door can help you set up these rules.
3. Monitor and Analyze Traffic. Use Azure Application Insights to monitor and analyze the traffic hitting your application. This can help you identify the source of these requests and take appropriate action.
4. Update Robots.txt. If these requests are coming from well-behaved bots, updating your robots.txt file to disallow these paths might reduce the frequency of such requests.
5. Check for Misconfigurations. Ensure there are no misconfigurations in your application or any linked services that might be causing these requests.