Your site was hacked? Your site got changed and maybe only displays a slogan like "Hacked by 133t-HaX0r" or something similar? You found unknown files or maybe got a mail from your hoster, claiming that there was a virus on your website?
None of these events should be brushed away casually! This always means that a malicious person has gained unauthorised access to your website.
This person can now not only change your website and for example modify your content or destroy the site completely, but also use your webspace as a platform to attack others or commit criminal acts through your webspace. For example your webspace could be used to do a denial of service attack on other sites or additional hacking attempts could be started from your server towards third parties. They can also user your webspace as storage for their illegal or criminal files.
Of course your are not automatically responsible for the felonies commited by others with the help of your webspace, but in worst case you can be partly liable for the damages that resulted from this, when you knew about an issue with your website, but did not act in a timely manner. Thus excuses like "The site isn't important anyway anymore" or "The site still does work, so why should I invest money and time into this now?" absolutely do not count. A hacked site should always be repaired as fast as possible or removed from the net entirely!
Unfortunately hackers do not target just the Big Ones like ebay or Amazon, but all websites out there. Thanks to automated tools there is no site out there that is not probed at least once a month, especially since the webspace can then again be used to stage even bigger attacks. Unfortunately by using a content management system, the attack surface does not get smaller either and despite other claims, the different CMS out there are not really different in that regard. Be it a large system or a custom made one, close- or open-source, Wordpress, Joomla or Drupal, they all had minor and major security issues, which resulted in hacking waves with thousands of hacked websites. However at the same time you should also know that all these hacks occured at a time when the projects had provided a fix for these issues. This makes updating your software so important and an absolute must.
If you, as an owner of a Joomla website, are affected by a hack, contact me. I will gladly help you to analyse the situation, clean your website from the attack and I will make sure that the original issue for the hack gets fixed. If you want to prevent something like this happening in the first place, maybe have a look at my longterm support offer.