Kon Boot

2009/07/22

I’m running behind the curve on this one, but after several of my usual sources suggesting KonBoot as a useful addition to any security toolkit. The premise of Kon-Boot is simple, by modifying the system kernel (Windows or Linux) upon boot there is no need to know the users password to access the system.

Kon-Boot is designed to boot via either floppy or CD, but thanks to the work of IronGeek it is relatively painless to get Kon-Boot running from USB.

Unetbootin continues to be a powerful tool, using which you create a bootable USB drive from the KonBoot floppy drive image. Raymond.cc has a great guide for the process, but ends with the limitation that KonBoot won’t function from USB; until IronGeek steps into the ring with a patch. Simply extract the archive to the root of the USB drive to update chain.c32 and syslinux.cfg then you’re good to go.

There are plenty of videos showing Kon-Boot in action, for example this one. I’ve successfully compromised a Windows 7 host, both local and domain acount, but it can only compromise domain accounts that have previously logged onto the physical machine. Discussing the issue with a Windows admin there have been a couple of potential mitigations developed, but at this point these have yet to be put to the test.

Linux compromise seems to be less powerful as you log in as a new kon-usr user, albeit with UID 0 for superuser privs. Full authentication doesn’t seem available however; the kon-usr drops in at the command line but KDE kicks up an authentication error when trying to start a GUI session.

I still intend to test my Kon-Boot drive against a machine with an encrypted hard drive, I’m not convinced it will work as my current hypothesis is that the Kon-Boot Kernel modifications will be attempted before the drive is unencrypted. I’ll update once I’ve been able to put the hypothesis to the test in a lab.

For the time being Kon-Boot is a permenant addition to my tool-kit, as there are plenty of scenarios that make KonBoot a legitimate tool for both security and non-security techies alike. Thanks to www.piotrbania.com for development and release.

Andrew Waite

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  1. 2009/07/22 at 18:30

    Nice write up Andrew, it really is a cracking tool.
    The latest version also enables you to change the password apparently, so certainly a valuable tool.

    I also did a video on my blog to bypass on a Vista box.

    • 2009/07/22 at 18:35

      Cheers Dale, hadn’t noticed a utility to change password. I’ll need to investigate further

  2. Mehmet Ulas
    2010/09/09 at 18:17

    Hi, any updates on running Kon Boot on an encrypted hard drive?

    • 2010/09/10 at 07:40

      The KonBoot FAQ states no.

      I haven’t put it to the test but; if the drive is unencrypted before the system boots to KonBoot then it should still work (essentially no different to an unencrypted drive at this point?), but if you can bypass the FDE then you likely don’t need KonBoot either.

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