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Docker Image Insecurity

Posted by Soulskill on from the totally-secure-for-undefined-values-of-secure dept.

An anonymous reader writes Developer Jonathan Rudenberg has discovered and pointed out a glaring security hole in Docker's system. He says, "Recently while downloading an 'official' container image with Docker I saw this line: ubuntu:14.04: The image you are pulling has been verified

I assumed this referenced Docker's heavily promoted image signing system and didn't investigate further at the time. Later, while researching the cryptographic digest system that Docker tries to secure images with, I had the opportunity to explore further. What I found was a total systemic failure of all logic related to image security.

Docker's report that a downloaded image is 'verified' is based solely on the presence of a signed manifest, and Docker never verifies the image checksum from the manifest. An attacker could provide any image alongside a signed manifest. This opens the door to a number of serious vulnerabilities." Docker's lead security engineer has responded here.

8 of 73 comments (clear)

  1. Read the update by jbolden · · Score: 5, Informative

    Read the update. Pretty much the Docker team is implementing a container verification system and working through the details of decentralized security. v1 is part of the mechanism being in place. It assumes that an upstream verification is in place which is at best-semi helpful. Everyone agrees that the current system does nothing and the message is highly misleading in that it might lead someone to believe that there is a security system in place when the plumbing isn't finished.

    So there is no argument here between the parties (what nothing to fight about on /.). Worth pointing out to the /. community however not to take that message seriously yet.

    1. Re:Read the update by postbigbang · · Score: 4, Informative

      Seems as though you're giving them a free ride for a rather poorly implemented message. And this is Slashdot, where we'll fight if we feel like it.

      Docker's been pretty loose and fast, and "not taking that message seriously yet" in a supposedly production environment seems a bit sophomoric.

      --
      ---- Teach Peace. It's Cheaper Than War.
    2. Re:Read the update by Todd+Knarr · · Score: 4, Insightful

      Upstream verification won't help. The client has to verify that the image it received is the same one the server verified, otherwise someone can hack a router to silently redirect the client to a malicious server and serve up whatever image they want alongside a copy of the signed manifest for the official image and you're fsckd. What they need is:

      1. The manifest has to be signed.
      2. The manifest has to contain a secure checksum (cryptographic hash) of the official image the server has.
      3. The client has to verify the signature of the manifest to confirm that the manifest hasn't been altered and comes from the official source.
      4. The client has to verify that the checksum of the image it received matches the checksum for the image in the manifest.

      5. Step 4 is apparently what's missing from the client.

    3. Re:Read the update by postbigbang · · Score: 4, Interesting

      It's nice to try to deflate this, but the blunder and the QA mistake remain. As I like to hesitate on the side of caution, I'd change this quickly. Just agreeing that one screwed up and not halting distribution for this head-desk sort of error -- in the face of the enormous security risk endowed -- isn't quite satisfactory.

      I'm here to punish no one, but in a crazy sort of way, I find this one to be a bit mind-boggling, to the tune that each and every appliance that wasn't independently MD5'd is now a freaking five star security risk. Chain of authorities are tremendously important, and reasonable people would believe, mistakenly, that all is fine, when none of it now is, because the chain of authorities chain has been broken, and for what I know, from its inception.

      So you're telling me to cool down, and I'm telling you that every single Docker implementation is now reasonably suspect, because of this go-lightly screw-up.

      --
      ---- Teach Peace. It's Cheaper Than War.
  2. What is this new madness? by tgibson · · Score: 3, Insightful

    I'm about to leave for Sears, inseam and waist measurements in hand. And here I read that my image security is at risk. I better find a new brand of pants I guess.

  3. What? by ArchieBunker · · Score: 5, Insightful

    Don't tell us what the fuck a docker is or anything...

    --
    Only the State obtains its revenue by coercion. - Murray Rothbard
  4. Dockers is a brand of khaki garments by Anonymous Coward · · Score: 5, Funny

    Dockers is a brand of khaki garments and other accessories from Levi Strauss & Co.

    It's obviously a single pant-leg or shoe, hence, Docker, not Dockers.

    You're welcome.

  5. Love that response by Tailhook · · Score: 4, Insightful

    A summary of that wall-of-text "response" from the Docker "lead security engineer":

    "Bullshit, bullshit v1 bullshit. Bullshit discussions about bullshit CVE bullshit. (yes we know its broken) Bullshit v2 bullshit, next version bullshit Bullshit."

    If you can't dazzle them with your intelligence, baffle them with your bullshit.

    --
    Maw! Fire up the karma burner!