Is the cable system insecure?

Is the cable system insecure?
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Subject Author Date
Is the cable system insecure? Nonapeptide 10-03-2007
Posted by on October 12, 2007, 5:48 pm
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>
> No one said one had to use the same tuner to capture data going both
> directions.
>
> You can tune one device to (e.g.) 34.8 MHz to capture the upstream
> traffic and to (e.g.) 723 MHz to capture the downstream traffic.

My point was that you *can't* tune an off-the-shelf cable modem to
capture upstream traffic. To do that, you essentially have to build,
buy, or otherwise obtain something resembling a head-end modem (but not
an actual head-end modem, since the head-end expects to control all the
end-user modems connected to it and you don't want to control them, you
just want to snoop on them), which is well beyond the capabilities of
your average neighborhood hacker.

-Larry Jones

Oh, now don't YOU start on me. -- Calvin

NMFall 20%
Posted by on October 13, 2007, 7:48 pm
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Nonapeptide@gmail.com wrote:
>
> So, if I'm understanding correctly, as I sit here and look at my
> modem, its receiving downstream transmissions that are headed for me
> and every other cable modem subscriber in my area. The modem is
> selectively choosing to ignore all but the transmissions that are
> addressed to it (I'm supposing that it's filtering by IP address?). My
> mind's eye is picturing all downstream content that is intended for me
> being split to all nodes on my local last mile, but only being
> accepted by my modem. Is that correct?

Yes, although the RF network has its own addressing scheme, it doesn't
use IP addresses. Most cable systems allow multiple IPs behind a single
modem (although there may be an additional charge).

> Also, (again, if I understand correctly) each transmission that I send
> hits some kind of local aggregator (multiplexer?) which then, in hub-
> like fashion, repeats the transmission to every port, which includes
> every neighbor that has a cable modem as well as the upstream
> connection to the head end? Eek! Seems like a waste of bandwidth for
> the provider. Each last mile area of a cable provider's service is
> essentially a big MAN sized collision domain?

No. The transmissions that you send go to the local node over coax that
is shared with your neighbors, so they receive those transmissions but
the node itself only retransmits (over fiber) to the head-end so people
attached to other nodes don't see the transmissions. And the upstream
bandwidth is divided into specific time slots that are, for the most
part, preassigned to specific cable modems, so there are no collisions
except for the few slots that are left open for contention.

> Any word on what type of encryption cable providers use?

The packet data is encrypted using either 56- or 40-bit DES. The DES
keys are managed using RSA public-key encryption.

-Larry Jones

Even though we're both talking english, we're not speaking the same language.
-- Calvin

Posted by Bill M. on October 14, 2007, 12:20 am
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On Sat, 13 Oct 2007 12:43:13 -0700, Nonapeptide@gmail.com wrote:

>As for the wireless admonitions, I think WPA2 with a decent sized PSK
>is purported to be uncrackable.

WPA and WPA2 aren't crackable in the same way that WEP is so easily
cracked, but both flavors of WPA are susceptible to dictionary
attacks, and the nice thing is that you don't need to sit there and
gather tons of packets like you would for WEP.

--
Bill

Posted by Richard Steiner on October 19, 2007, 1:04 pm
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Here in comp.dcom.modems.cable,

>WPA and WPA2 aren't crackable in the same way that WEP is so easily
>cracked, but both flavors of WPA are susceptible to dictionary
>attacks, and the nice thing is that you don't need to sit there and
>gather tons of packets like you would for WEP.

How much more secure are you when you turn SSID broadcasting off?

I would think that would at least deter casual drive-by Wifi cracking
(folks can't crack what they don't know exists).

Or will some Wifi detectors show hidden wireless networks anyway?

--
-Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Mableton, GA USA
Mainframe/Unix bit twiddler by day, OS/2+Linux+DOS hobbyist by night.
WARNING: I've seen FIELDATA FORTRAN V and I know how to use it!
The Theorem Theorem: If If, Then Then.

Posted by Bill M. on October 19, 2007, 4:40 pm
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On Fri, 19 Oct 2007 12:04:39 -0500, rsteiner@visi.com (Richard
Steiner) wrote:

>Here in comp.dcom.modems.cable,
>
>>WPA and WPA2 aren't crackable in the same way that WEP is so easily
>>cracked, but both flavors of WPA are susceptible to dictionary
>>attacks, and the nice thing is that you don't need to sit there and
>>gather tons of packets like you would for WEP.
>
>How much more secure are you when you turn SSID broadcasting off?

Not more secure at all, IMHO.

>I would think that would at least deter casual drive-by Wifi cracking
>(folks can't crack what they don't know exists).
>
>Or will some Wifi detectors show hidden wireless networks anyway?

Yup, passive scanner programs like Kismet show those networks, too,
just as quickly and clearly as if they were broadcasting their SSID.
Active scanners, like Netstumber, won't show them. Disabling SSID
broadcast is a little like MAC filtering, it makes you feel good but
adds little or nothing in the way of additional security.

--
Bill

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