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Bug#569222: risky use of mount from a random partition



Package: os-prober
Severity: normal
Tags: security

To mount a /boot partition, os-prober uses the mount binary from the
linux system it is probing. There's a possible security risk here.
Imagine if a compromised system is being reinstalled using a new drive,
and the compromised drive is still connected. An attacker who wanted to
target d-i could arrange for mount to copy itself over to /target when
run. Or a virus, not targeting d-i at all, could infect /target.

------------------------------------------------------------------------
r50221 | cjwatson | 2007-11-22 13:16:50 -0500 (Thu, 22 Nov 2007) | 2 lines

* Try finding a LABEL/UUID-capable /bin/mount in $tmpmnt as well as in
  /target.
------------------------------------------------------------------------

I'm wondering what was the rationalle for needing to do that, and why
does the code use the mount from the system being probed, in *preference*
to the one in /target? Perhaps the idea was that a distribution's fstab
might use special features that are only available with its version of
mount, if so I hope that Debian's mount has caught up..?

Also, since we have a udeb containing libblkid, perhaps it's time to
spend the 100k of ram to have os-prober-udeb depend on a mount-udeb
and remove this hack. IIRC this is the last place where d-i runs
binraries from /target or elsewhere w/o chrooting, which has caused
other problems before.

-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.31-1-686 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

-- 
see shy jo

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