Is it a sign of hacking?

Question

Currently, I've seen this strange error log and I really don't understand about what this meant. Regarding to this log, if it is an activity of hacking I have two questions:

1. What are they trying to do ?
2. What else should I do in order to detect whether my system is safe and robust?

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Answer 1

This is an already understandable problem with Apache servers

This kind of access is usually made by bots, and the main and bottom line issue here is a few exposure that your sever should be open to.

Apache permits every directory to have a .htaccess file for controlling or restricting access. This gives users directory-level control. If I want to return a blank page in place of an HTTP 403 error message, I can simply add a control line to my .htaccess file:

The error identifies the server's version information at the bottom of the error message. For non configured .htaccess

Keep in mind, this information disclosure does not stop with one URL. Microsoft appends the long garbage characters to lots of different URLs on my site. If any URL silently redirects to a different server, then Microsoft will be able to see the version string change. This permits Microsoft to map out my back-end server architecture.

Mitigating Exposure So how do you stop this information disclosure? The answer is relatively easy: place the ErrorDocument line in the only configuration file that is processed prior to the user-level .htaccess files. On my server, that's "/etc/apache2/httpd.conf". By default, the httpd.conf file is empty. On my server, it now contains one line:

Reference: http://www.hackerfactor.com/blog/index.php?/archives/2014/07/06.html