I've noticed recently that the IP 188.8.131.52 is testing several servers, requesting for files related to FCKeditor and then checking for the availability of the connectors to perform operations on the server (usually I think that it's more common requests related to tinymce filemanager, but it doesn't really matter too much).
I don't think that the requests are related to an unknown problem with the server connectors in FCKeditor as it seems to search both the asp and aspx versions (maybe it acts depending on the server software), but there are a few points that everybody should remember in order to avoid problems.
As every other time that I've written about this issues, let me remember you that I'm not a security expert and these are just some basic guidelines, the basis is that you should try to create an onion around the security of your server, different layers so that an attacker has to go through all of them, and hopefully he should be stopped at the very first steps.
Keep only the needed files
Whenever you use a third party software (or even your own software), don't upload to the server everything that comes in the shipped distribution. You won't need at the server source files, samples, documentation, or integration files for other server languages.
By removing those extra files you are avoiding a larger vulnerable surface and you can focus on the important files.
Security by obscurity can be useful
Yes, security by obscurity isn't really secure, but this kind of automated attacks that just search any number of domains for some files at specific locations like "/FCKeditor/editor/filemanager/connectors/aspx/connector.aspx?Command=GetFoldersAndFiles&Type=File&CurrentFolder=/" can be avoided if you place this 3rd party components in a non-standard location, so something as easy as putting the FCKeditor in another subfolder can avoid that an automated attack finds your files.
It's also important that the files that the users upload to your server with scripts like the FCKeditor server upload, don't end up in a folder that gives any hint about how they have been placed there, if your files are under /scripts/CKFinder/userfiles I'll know that you are using CKFinder somewhere in your server and more important, you are stating the path for CKFinder so you are weakening a little the security that you got in the first place by using /scripts/CKFinder instead of just /CKFinder
Expose the upload script only to users that can upload files
If a user doesn't have permissions to upload anything, then he shouldn't be able to see any hint about what are you using to manage the files in your server.
Secure the upload folder
The folder where the users are able to upload files shouldn't have permissions to execute any script, so even if they are able to upload a script, it won't do anything. Using the IIS control panel or .htaccess files in Apache it's easy to perform this task.
Keep your code updated
This can be a pain, but you once you start using a script at your server, you should check from that moment any new release about that project, paying special attention to warnings about security problems in new releases. I think that every project has some kind of RSS feed, so it shouldn't really be that hard to at least notice the new versions.
Enable file management wisely
In FCKeditor and CKFinder the server connectors include a config file where you can adjust some parameters (location of uploaded files, allowed or disallowed extensions, types of files, etc...) but the most important one is the ability to state if the script is enabled or disabled.
By default the server connectors are disabled in FCKeditor and CKFinder as that's the safe default, but people the complain that when they try to use them they get a message stating that the connector is disabled. Of course, that kind of people are showing that they didn't bother to read the minimum about how to configure these scripts, so they might end up using other ones that are enabled by default and they won't ever notice that now everyone can manage the files of their servers.
The correct step is to use the login credentials of your CMS to enable the file management only for the correct users, you don't really want an anonymous user being able to upload a file to your server.
Finally: be careful
As you can see, I'm not revealing anything extraordinary, these are just some basic rules that can provide some basic protection, but there are more that you should be aware of and that's part of the task of managing a web server.
When you pick a file manager for your server, don't think only about a few buck that you can save by using a free manager instead of a paid one, check how the security is implemented in each one, if an attacker is able to get control of your server you can lose many times that money trying to getting it back to normality.