Hello all.  I am getting exceptions in my error log from a suspicious looking request:

/dotnetnuke/linkclick.aspx?tabid=145&link=197'%20and%20user%3E0%20and%20''='

It looks like someone is trying to do something malicious with an encoded query string.  What really gets my attention is that the exception is DotNetNuke.Common.Utilities.FileSystemUtils.DownloadFile which makes me think they are trying to download files off our website.

Does anyone know what is going on here?

AssemblyVersion: 04.06.00
PortalID: 1
PortalName: XXXXXXXX
UserID: -1
UserName:
ActiveTabID: 145
ActiveTabName: XXXXXXXXX
RawURL: /dotnetnuke/linkclick.aspx?tabid=145&link=197'%20and%20user%3E0%20and%20''='
AbsoluteURL: /dotnetnuke/linkclick.aspx
AbsoluteURLReferrer:
UserAgent:
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: d5035688-81e4-441f-98b3-55e9e7dd1ed9
InnerException: Unhandled Error:
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: DotNetNuke.Common.Utilities.FileSystemUtils.DownloadFile
StackTrace:
Message: System.Exception: Unhandled Error: ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Common.Utilities.FileSystemUtils.DownloadFile(Int32 PortalId, Int32 FileId, Boolean ClientCache, Boolean ForceDownload) at DotNetNuke.Services.FileSystem.FileServerHandler.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) --- End of inner exception stack trace ---
Source:
Server Name: XXXXX