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Wordpress Remote Exploit - W3 Total Cache

Hi all,

From the developers' description [1], W3 Total Cache is:

The most complete WordPress performance framework. Recommended by web hosts like: MediaTemple, Host Gator, Page.ly and WP Engine and countless more. Trusted by countless sites like: stevesouders.com, mattcutts.com, mashable.com, smashingmagazine.com, makeuseof.com, yoast.com, kiss925.com, pearsonified.com, lockergnome.com, johnchow.com, ilovetypography.com, webdesignerdepot.com, css-tricks.com and tens of thousands of others. W3 Total Cache improves the user experience of your site by improving your server performance, caching every aspect of your site, reducing the download times and providing transparent content delivery network (CDN) integration. Downloads: 1,388,876 Ratings: 4.6 out of 5 stars

Unfortunately, it's frequently incorrectly deployed. When I set it up by going to the Wordpress panel and choosing "add plugin" and selecting the plugin from the Wordpress Plugin Catalog (or whatever), it left two avenues of attack open: 1) Directory listings were enabled on the cache directory, which means anyone could easily recursively download all the database cache keys, and extract ones containing sensitive information, such as password hashes. A simple google search of "inurl:wp-content/plugins/w3tc/dbcache" and maybe some other magic reveals this wasn't just an issue for me. As W3 Total Cache already futzes with the .htaccess file, I see no reason for it not to add "Options -Indexes" to it upon installation. I haven't read any W3 documentation, so it's possible this is a known and documented misconfiguration, but maybe not. 2) Even with directory listings off, cache files are by default publicly downloadable, and the key values / file names of the database cache items are easily predictable. Again, it seems odd that "deny from all" isn't added to the .htaccess file. Maybe it's documented somewhere that you should secure your directories, or maybe it isn't; I'm not sure. If I had to categorize these holes, I'd say they're due to "misconfiguration", but I figure it's relevant to write in to full-disclosure & webappsec because I'm usually not horrible with configuring things and I made these mistakes several times without realizing. I'm copying the author on this email, as he may want to include a warning message where nieve folks like myself can see it, or document these somewhere if they're not already, or at least apply the two .htaccess tweaks mentioned above. Anyway I put together a short and simple shell script that works pretty decently against my own various wordpress websites, and exploits the configuration error in point (2) above. Exploiting point (1) can be done with wget & grep and is even more dull than the below exploit. **************** W3 Total Fail Exploit for point (2): http://git.zx2c4.com/w3-total-fail/tree/w3-total-fail.sh (Read the entire usage message.) Screencast for point (2): http://git.zx2c4.com/w3-total-fail/plain/screencast.ogv or https://www.youtube.com/watch?v=sqZ_zYLFDSo **************** Merry Christmas. - Jason zx2c4 [1] http://wordpress.org/extend/plugins/w3-total-cache/ _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/

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