HTTP error code 404 showing up repeatedly in the logs

[scottw12]

I keep getting this log entry over and over. Anyone else have this pop up?

HTTP Error Code 404 Page Not Found
TabId PortalAlias dev.jcesba.org OriginalUrl /Portals/0/ Url https://
TabId:
PortalAlias:dev.jcesba.org
OriginalUrl:/Portals/0/
Url:https://dev.jcesba.org/Portals/0/
UserAgent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36
HostAddress:xxx.xxx.xxx.xxx
HostName:xxx.xxx.xxx.xxx
Server Name: NBBIT02

[meetmandeep]

I haven't seen that in particular. Are able to reproduce it? For example, does it happen when you view a certain page or setting?

[scottw12]

Odd things are even happening when no one is in editing the site...The is a dev site not readily known, but it is on the net. I am now suspecting some kind of hacking going on as I am seeing some very weird log entries along with the 404 error reported above.

Like this one:
Page Load Exception
AbsoluteURL /default.aspx DefaultDataProvider DotNetNuke.Data.SqlData
AbsoluteURL:/default.aspx
DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke
ExceptionGUID:fad65c43-fc5a-4ab8-a281-7ea3e2b9e873
AssemblyVersion:9.7.2
PortalId:-1
UserId:-1
TabId:-1
RawUrl:/

Referrer:
UserAgent:Expanse, a Palo Alto Networks company, searches across the global IPv4 space multiple times per day to identify customers' presences on the Internet. If you would like to be excluded from our scans, please send IP addresses/domains to: scaninfo@paloalt

ExceptionHash:1FGHRi1nJ0mTVlqPSb2wjJ/9hTQ=
Message:Object reference not set to an instance of an object.
StackTrace:
InnerMessage:Object reference not set to an instance of an object.
InnerStackTrace:

I would be more than happy to give you the access needed to track this down

[meetmandeep]

That explains it. It looks like a bot (do a Google Search on "Expanse UserAgent Palo Alto") is randomly hitting part of the URLs for sniffing.