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Entropy Problems For Linux In the Cloud

Posted by kdawson on from the mehr-Zufälligkeit dept.

CalTrumpet writes "Our research group recently spoke at Black Hat USA on the topic of cloud computing security. One of the interesting outcomes of our research was the discovery that the combination of virtualization technologies and public system images results in a problem for random number generation on guest operating systems. This is especially true for Linux, since its PRNG uses only a small set of entropy-gathering events, and virtual Linux images often generate SSH host keys within seconds of their initial boot. The slides are available; the PRNG vulnerability material begins at slide 63."

1 of 179 comments (clear)

  1. Linux has a paravirtual entropy driver by Anthony+Liguori · · Score: 5, Insightful

    CONFIG_HW_RANDOM_VIRTIO enables it. It's been there for quite a while.

    We could easily support it in KVM but I've held back on it because to really solve the problem, you would need to use /dev/random as an entropy source. I've always been a bit concerned that one VM could starve another by aggressively consuming entropy.

    lguest does support this backend device though.