New dat files in WordPress root

Image via Wikipedia

I woke up this morning to find a ton of randomly-named files in the root directory of several of my WordPress installations. The files are named similarly to 0303c831c9c6203ba966dbf523d119ab.dat. The data of these files looks like a serialized PHP value.

I’m not sure if these files are due to the upgrade I performed to WordPress 3.0.1 last night, though they seemed to begin appearing shortly after I applied that upgrade. I’m speculating that they’re due to the way one of my plugins – perhaps Hyper Cache – is interacting with 3.0.1. It’s either that or some malicious infection. Either way, I’ll update here when I find out what’s causing it.

Have you noticed extra, random files in your WordPress installation after upgrading to 3.0.1? If so, hit the comments.

UPDATE: It looks like I can confirm that the problem was due to the Hyper Cache plugin. Upon automatically upgrading to the latest version of the plugin, 2.7.3, WordPress complained that it couldn’t find a cache directory and instructed me to create that directory. Even though I did, it seems it was still storing the cache files – these mysterious .dat files – in the WordPres root directory. After deactivating and reactivating the plugin, it seems to be storing the cache files in the correct location now.

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Aaron Traffas, CAI, ATS, CES | |

Aaron Traffas, CAI, AMM, CES, is an auctioneer from Medicine Lodge, Kansas. He is currently community evangelist for Purple Wave in Manhattan, Kansas. Aaron serves as the current president of the Kansas Auctioneers Association and in the past has served on the National Auctioneers Association Education Institute Board of Trustees. He is a past instructor at CAI and co-wrote and instructed the ATS designation course from NAA. He currently instructs the Internet Auction Methods course offered by the NAA. An active contract bid caller, he has competed in multiple state auctioneer contests including placing twice within the top 5 in Kansas. During the summer, Aaron operates a farm in south central Kansas. Aaron is an active singer and songwriter and the Aaron Traffas Band's latest release, Enter: The Wind, can be found at iTunes, Amazon and Spotify.
  • Sabo

    Google catch your post pretty quick, for the good of everybody with the same problem. This solved my problem, Hypercache created almost 3,000 .dat files in the root. My question is, who give the plugin permission to write outside his folder? Apache, PHP? this is a security issue.

  • twist3r

    It happend to me too, even if the plugin was inactive.

  • Thanks – this happened to us to. We also had thousands of these files. Worrying really that it could write to the root.

  • Mike233

    Hey, i am having this same problem, i tried disabling and enabling the plugin but .dat files are still there, any other ideas??

    • Did you crate the cache subdirectory under wp-content/plugins/hypercache?

      • Mike233

        Apparently i wasnt able to create the directory, how can i create it now ? btw my wp files are not showing anymore just a lot of .dat files on my root :S

        • You should be able to create it easily with an FTP client – I like Filezilla.

          • Mike233

            i kno but when i create a new dir it disappears, it only leaves the .dat files :(:(