nanog mailing list archives
Re: First real-world SCADA attack in US
From: Brett Frankenberger <rbf+nanog () panix com>
Date: Tue, 22 Nov 2011 09:30:30 -0600
On Tue, Nov 22, 2011 at 10:16:56AM -0500, Jay Ashworth wrote:
----- Original Message -----From: "Brett Frankenberger" <rbf+nanog () panix com>The typical implementation in a modern controller is to have a separate conflict monitor unit that will detect when conflicting greens (for example) are displayed, and trigger a (also separate) flasher unit that will cause the signal to display a flashing red in all directions (sometimes flashing yellow for one higher volume route). So the controller would output conflicting greens if it failed or was misprogrammed, but the conflict monitor would detect that and restore the signal to a safe (albeit flashing, rather than normal operation) state."... assuming the *conflict monitor* hasn't itself failed." There, FTFY. Moron designers.
Yes, but then you're two failures deep -- you need a controller failure, in a manner that creates an unsafe condition, followed by a failure of the conflict monitor. Lots of systems are vulnerable to multiple failure conditions. Relays can have interesting failure modes also. You can only protect for so many failures deep. -- Brett
Current thread:
- Re: First real-world SCADA attack in US, (continued)
- Re: First real-world SCADA attack in US Charles Mills (Nov 21)
- Re: First real-world SCADA attack in US Mark Radabaugh (Nov 21)
- RE: First real-world SCADA attack in US Jason Gurtz (Nov 21)
- Re: First real-world SCADA attack in US Christopher Morrow (Nov 21)
- Re: First real-world SCADA attack in US Jimmy Hess (Nov 21)
- Re: First real-world SCADA attack in US Jay Ashworth (Nov 21)
- Re: First real-world SCADA attack in US Jussi Peltola (Nov 21)
- Re: First real-world SCADA attack in US Valdis . Kletnieks (Nov 21)
- Re: First real-world SCADA attack in US Brett Frankenberger (Nov 22)
- Re: First real-world SCADA attack in US Jay Ashworth (Nov 22)
- Re: First real-world SCADA attack in US Brett Frankenberger (Nov 22)
- Re: First real-world SCADA attack in US Charles Mills (Nov 21)
- Re: First real-world SCADA attack in US Matthew Kaufman (Nov 22)
- Re: First real-world SCADA attack in US andrew.wallace (Nov 22)
- Re: First real-world SCADA attack in US Michael Painter (Nov 22)
- Re: First real-world SCADA attack in US Joe Hamelin (Nov 22)
- Re: First real-world SCADA attack in US Mike Andrews (Nov 23)
- Re: First real-world SCADA attack in US Valdis . Kletnieks (Nov 22)
- Re: First real-world SCADA attack in US Steven Bellovin (Nov 22)
- Re: First real-world SCADA attack in US Steven Bellovin (Nov 22)
- Re: First real-world SCADA attack in US Michael Painter (Nov 22)
- Re: First real-world SCADA attack in US Ryan Pavely (Nov 22)