dgfrench on "All plugins disappeared"

All of my plugins disappeared from the WP browser admin interface yesterday. I took a server snapshot & am following suggestions from:

this post

It does appear that there was a line of code injected into each PHP file within the plugins.

Anyone else ran into this & have suggestions other than what is offered up in the other post? I was running 4.0.1 but just updated and am filling the other holes with concrete as I go. I suppose the best way to learn WP security is in progress. Sigh..

Thanks in advance for any help you can offer!