Security audits are not cheap FYI. I can't technically offer my help officially because my account is too new and I want to respect the rules here, but I can list some things to check on.
Are you running your own VM? Check that SSH is locked down, root cannot login, ports other than the ones you need for your site are closed off and keep your box up to date. If you're running a webapp, be sure to keep dependencies updated as well.
You should note that I am not a security professional by trade or job title, I hold no certs and I'm not a "hacker" but I have spend enough time in the space to know the common holes to look for a fix. I also do my fair share of... shall we say "exploration" on the internet in my spare time.