Help! My site is trojan infected

You can fix it yourself.. tighten up the chmod settings on everything.. 777 is asking for trouble.

Change your passwords on everything, and deleted the infected files.

I'm sure other Warriors will have more suggestions. I've had this happen a couple of times, it scares you the first time but don't worry, it can and will be fixed.

Now go to Google Webmaster tools and see if they have dected any problems. Once you have cleaned things up, ask them to review your site again. If it's left like this for too long your site will drop in the SERPs.

Some of mine too, it happens, just get your host run a back up. It will be sorted in time.
Could also be on the server side of your host.

First - tell your host. They need to remove the infected machine from service and replace it with one that hasn't been compromised and is up to date with security fixes.

Second - examine any server side scripts you have to security vulnerabilities. If you are using third party scripts - make sure you are using the most recent version and that there are no reported vulnerabilities.

Third - reupload the site to the clean server.

I'm not a server guru, but here is what I have to say.

If the server provider you are using does not have great security, it can easily be affected. Locating the initial source can be very hard. Because a lot of servers are shared among many clients, it could have been someone else's data which infected the server, which eventually spread to all the data on the server (including yours) and eventually everyone who views/downloads/whatever from information stored on that server (such as the person you spoke of).

I would contact your Web Hosting Provider and ask them about the security of their servers. Most places should scan for stuff and should keep things up to date so things like that don't happen. If you find out there are flaws in their security, you might want to think about transfering to another provider.

I created a free tool to clean infected files.
I posted details in this thread, perhaps you can use it.

Good luck,

Rembo