<PackageReference Include="System.Security.Permissions" Version="10.0.5" />

System.Net.WebPermissionAttribute

Specifies permission to access Internet resources. This class cannot be inherited.
namespace System.Net { public sealed class WebPermissionAttribute : CodeAccessSecurityAttribute { public string Accept { get; set; } public string AcceptPattern { get; set; } public string Connect { get; set; } public string ConnectPattern { get; set; } public WebPermissionAttribute(SecurityAction action); } }