Let me tell you about that time my site got hacked.
Once upon a time I received this email from Google. Now when Google emails you, you usually pay attention, even it it’s a bot. Those guys know their stuff.
The email told me that my site was possibly hacked because it was suddenly feeding spam when the Google bot was passing by.
The reason why I got this email is because I use the free web master tools from the G btw. That way they know my site has behaved nicely over the years, and when it suddenly started spewing spam, they knew something bad was up.
The scary part is that this only happened when Googlebot was munching my pages. Not when I or any other human passed by with a browser. So in other words, I didn’t have a clue.
Because it was quite the mystery, I checked my web folder and found a few suspicious files and folders in there. Suspicious, because I never put them there.
I found a folder named “coockies“, an unknown common.php, session.php and coockies.txt file. My .htaccess file was also changed. All php files and the .htaccess had the same timestamp. I compared my complete WP installation with the original installation files to be sure no other files were modified, which turned out to be the case.
The folder seemed to contain files with file names resembling URIs of my blog posts. The content was unreadable and appeared garbage. I’m guessing it was an encoded version of the spam my site was feeding Google.
At first I thought my WP blog was hacked, but the entry point was simply the modified .htaccess file. It contained a few new rewrite rules which checked the user agent of the incoming request, and if that matched any of the major crawlers, it would redirect to the new php files, which would feed the spammy content.
Cleaning up turned out to be rather easy.
I deleted all the new files, restored my old .htaccess file (hurrah for backups) and changed my site passwords just to be sure.
The fishy thing about all this is that I’m still not sure how these files got on my system (hence the password changes). The timestamp on the files seemed to point to the moment I last ran a WP and plugin update on my site. Maybe it was pulled in with a compromised plugin, but there is no way to tell which one it could have been. Another option is a compromised FTP account, but that password was already random before I changed it so that seems unlikely. I still changed it to a random and longer one to be sure.
I also took some extra defensive measures to try to avoid this kind of hack in the future, but that’s for another post.