nanog mailing list archives
Re: First real-world SCADA attack in US
From: Matthew Kaufman <matthew () matthew at>
Date: Tue, 22 Nov 2011 14:59:43 -0800
On 11/22/2011 5:59 AM, Brett Frankenberger wrote:
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. -- Brett
Indeed. All solid-state controllers, microprocessor or not, are required to have a completely independent conflict monitor that watches the actual HV outputs to the lamps and, in the event of a fault, uses electromechanical relays to disconnect the controller and connect the reds to a separate flasher circuit.
The people building these things and writing the requirements do understand the consequences of failure.
Matthew Kaufman
Current thread:
- Re: First real-world SCADA attack in US, (continued)
- 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 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)
- Re: First real-world SCADA attack in US andrew.wallace (Nov 22)