From: Ng, Kenneth (US) (kenng@kpmg.com)
Date: Wed Jun 23 2004 - 15:06:26 EDT
Depends on how cheaply the unit was designed. I remember putting in back to
back diodes on the front gates to protect against stuff like static
discharge. If this was done, you would have to generate a HELL of a lot of
EMF to blow these out. Time to bring out the van-de-graf generator :-).
But in this era of cheaper cheaper cheaper, I bet these aren't there
anymore. What will probably happen is you'll DOS the box. The AGC on the
front end will try to cut the signal back as far as it can, probably not
enough, the decoders won't see a clear signal/sequence, so will probably
fail to engage. But I wouldn't be surprised if you burned out a front end.
-----Original Message-----
From: Mister Coffee [mailto:live4java@stormcenter.net]
Sent: Wednesday, June 23, 2004 2:03 PM
To: Ng, Kenneth (US)
Cc: 'Mister Coffee'; Richard Rager; Amit Deshmukh;
pen-test@securityfocus.com
Subject: Re: RF code scanners
On Wed, Jun 23, 2004 at 08:58:38AM -0500, Ng, Kenneth (US) wrote:
> Safe is tricky. Electronic door locks are supposed to fail open in case
of
> fire or power failure.
>
That depends on the specific type of lock. Yes, many of them do
fail-unlocked in case of power failure. But many of them, particularly in
Exterior Facing situations will fail locked, but have a physical "safety
bar" release on the inside. That solves the safety needs.
Garage doors, gates, etc, are a different animal. Most electric garage
doors I've encountered (and gates) can't be opened during a powerfailure
without either physically forcing the device, or entering the garage and
pulling a manual release lever.
My curiosity here isn't how they'll behave in the case of power outage, but
what happens when you overload the receiver's front end with 100+ * normal
signal. Do they blow chunks and open? Simply reset and go silent for a
while? Or make a premature trip to Silicon Heaven.
Cheers,
L4J
> -----Original Message-----
> From: Mister Coffee [mailto:live4java@stormcenter.net]
> Sent: Friday, June 18, 2004 12:38 PM
> To: Richard Rager
> Cc: Amit Deshmukh; pen-test@securityfocus.com
> Subject: Re: RF code scanners
>
>
> On Thu, Jun 17, 2004 at 05:19:09PM -0600, Richard Rager wrote:
> > On Thu, 17 Jun 2004, Mister Coffee wrote:
> > > That depends on what you're trying to do.
> > > Side note:
> http://www.radioreference.com/modules.php?name=News&file=article&sid=467
> > > Openers are decidedly susceptible to jamming...
> > All FCC class C devices are susceptible to jamming. Look at wireless
> > alarm systems.
> >
>
> I wonder how many of these devices are designed to "Fail Open" when their
> receivers are overwhelmed. I don't imagine it would take much power to
> completely overload the front end of most garage door openers and the
like.
>
> The "safe" way would be to "fail closed" of course, but we all know how
> security conscious most of the manufacturers out there are.
>
> Cheers,
> L4J
>
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