full-disclosure - Re: debugfs exploit for a number of Android devices

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Message-ID: <CAPRTkJgFjvZt8WUrzD0LyubKqpUE+djo29xqrqDn3gtmN_s71Q@mail.gmail.com>
Date: Wed, 15 Aug 2012 08:41:26 -0500
From: Alexander Pruss <arpruss@...il.com>
To: Dan Rosenberg <dan.j.rosenberg@...il.com>
Cc: full-disclosure@...ts.grok.org.uk
Subject: Re: debugfs exploit for a number of Android
	devices

On Wed, Aug 15, 2012 at 8:10 AM, Dan Rosenberg
<dan.j.rosenberg@...il.com> wrote:
> This also can't be used by malicious apps, since you need user/group "shell"
> to replace /data/local/tmp with a symbolic link, and normal applications
> cannot be granted this user/group.

You're right: my apologies.  I didn't really look at how this exploit works.

And you're certainly right that making /data writeable is a better way
to exploit it.

I just confirmed that on my 2.3.6 Epic 4G Touch there is no issue: a
directory symlinked to /data/local/tmp does NOT get its permissions
changed on boot.

I am not sure I would say that it's erroneous to make /data/local
writeable by adb shell.  It may be handy for a developer with an
unrooted device to put various commandline utilities in /data/local,
such as a better busybox.

Alex

-- 
Alexander R. Pruss
arpruss@...il.com

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