Thanks to Laurie Thomas of Maritime Security/MTSA News
for pointing me at a Coast Guard blog
post about a safety
alert the Coast Guard has issued about outages of the GPS navigation
system. The safety alert describes a GPS outage noted recently at a ‘non-US
port’ that covered a significant area of that port and surrounding ocean.
The Coast Guard is obviously concerned with outages like
this being a hazard to navigation and that is the point of their alert. Other
users of the GPS navigation system should also be similarly concerned. More
important to readers of this blog are the potential effects of these types of
outages could have on SCADA systems that use the GPS for control system timing.
The Safety Alert does not characterize this particular outage
as either natural or man-made. From the point of view of the Coast Guard, this apparently
isn’t really important as either would have similar effects on navigation. That
is probably short sighted as someone that deliberately jams GPS signals over this
large an area is probably intending to use that disruption to have other, more
serious effects on maritime traffic.
In many ways industrial control system owners should follow
the general guidelines in the Safety Advisory. They need to have in place plans
for using alternative methods of timing synchronization during local GPS
outages. More importantly they need to think about the potential security
implications for such outages as they may signal an attempt to disrupt or gain
access to remote SCADA installations as part of an attack on the ICS network.
NOTE: I have commented elsewhere that it would have been
more helpful if the Coast Guard had characterized the reported outage as either
man-made or natural. If natural it is a clear reminder that satellite communications
of all sorts can be disrupted by geomagnetic storms. If man-made it is a clear
declaration that at least one attacker has shown the ability and willingness to
use wide spread GPS jamming with a certain level of immunity.
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