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Unit 9: System Security

The cyberthief can then ask the local name server for the IP address for XYZ Bank’s home page Notes
and learn when it will expire. At the moment of expiration, he again asks for the bank’s address
and immediately sends out the 65,536 answers that list his own computer’s IP address as that
of the bank. Under the DNS protocol, the local name server simply accepts the first answer that
matches its codes; it does not check from where the answer came, and it ignores any additional
replies. Even though XYZ Bank’s IP address has not really changed, the local name server still
replaces the correct address with the hacker’s address and communicates the false information
to customers.

So, if our hacker gets his answers in first, the local name server will direct customers seeking
XYZ Bank to his computer. Assuming that the hacker runs a convincing imitation of the bank’s
sign-in page, customers will not realize that they are handing their confidential information
over to a fake.
Similar flaws plague other Internet protocols, such as the Border Gateway Protocol (BGP),
which governs the pathways followed by data packets on the Internet. They also affect the
Dynamic Host Configuration Protocol (DHCP), which roaming computers utilize to find network
resources when they are connected in new locations. For example, suppose you are sitting in
your favorite coffee shop and want to open a connection to the shop’s wireless router. Your
laptop broadcasts a query for the server to identify itself, and DHCP directs that your laptop
will accept the first response it gets as legitimate. If a hacker sitting across the room can fire off
a reply before the coffee shop’s router does, your laptop will be connected to his. Everything
will seem normal to you, but his computer can record all your communications and covertly
direct you to malicious sites at will.
Such vulnerabilities imperil more than individuals and commercial institutions. Secure
installations in the government offices and the military can be compromised this way, too. And
indeed there have been cases in which these loopholes did allow data to be stolen and records
to be altered.
How do we come to be in such a mess? The reasons are partly historical. Today’s protocols
descend from ones developed 35 years ago when the Internet was still a research network. There
was no need to safeguard the network against malicious entities. Now the Internet has opened up
and grown explosively, but we have not developed inherently stronger security—the protocols
still take for granted that the billions of people and devices online are both competent and
honest. Nobody ever went back to do the difficult job of developing inherently stronger security.

Fixing the Internet protocols will be a formidable challenge. Some improvements are relatively
simple to imagine—for example, switching to identification codes that use more than 16 bits—
but would involve considerable work to adopt on a global basis. Techniques for authenticating
that messages coming from the proper parties are well-developed, but those technologies are
not necessarily fast enough to be embedded in all the routers on the Internet without bringing
traffic to a crawl (or forcing prohibitive investments in new equipment). Some other important
kinds of protocol improvements still need to be conceived. Of course, an essential feature of
any new protocol is that it can be implemented without seriously disrupting Internet operations
in the process.
For these reasons and more, in its February 2005 report, the President’s Information Technology
Advisory Committee (PITAC), of which I was a member, strongly recommended increased
federal funding for basic research into cybersecurity. The Department of Homeland Security
currently devotes only one-tenth of 1 percent of its research budget to this concern. DARPA (the
Defense Advanced Research Projects Agency) used to fund this kind of work more generously
but its current focus is more narrowly military and its research on cybersecurity is classified,
limiting the amount of research that can be conducted at universities, and inhibiting the transfer
of technology to industry. The National Science Foundation studies the problem but can only
do so much. And, although industry takes the problem seriously, inadequate profit incentives
discourage companies from aggressively developing broad-based solutions.

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