By Elias Levy A recurring argument in the computer security world is that clamping down
on the dissemination of information about vulnerabilities, and tools that
exploit them, will mitigate everyone's risk. Last week, one proponent of
this argument, Scott Culp, manager of Microsoft's security response
center, coined the term "information anarchy" to describe the current
situation, comparing it with yelling "fire" in a crowded movie house.
It appears Culp is more comfortable with an "information dictatorship" or
"information oligarchy" model, and has entirely missed the fact that the
movie house is on fire.
A successful attacker requires three things: the opportunity to launch an
attack, the capacity to successfully execute the attack, and the
motivation to attack. An opportunity to launch an attack requires a
vulnerable system and an access path to the system. The capability to
successfully execute the attack requires knowledge of the vulnerability
and the tools to exploit it.
Proponents of the information dictatorship argument are targeting the
second requirement of a successful attacker: his capability to launch an
attack. This approach to the problem of computer security is flawed, and
can only fail.
First, we cannot stop some small number of malicious users from gaining
knowledge of vulnerabilities, or access to the tools that exploit them.
Vulnerability information and exploits have legitimate uses with the
computer security field. They are part of research, are required in
penetration testing, and used by system administrator to test their
systems, mitigate the risks by gaining an in-depth understanding of the
problem, and to verify that vendor fixes work as advertised.
We live in an open society. It is impossible to distinguish a potential
attacker from a legitimate user of the information. Thus, it is impossible
to compartmentalize the information and still make it available to
everyone who legitimately needs it.
PLAYING MAKE BELIEVE.The commonly proposed solution to this problem is to artificially restrict the information to a subset of legitimate users, marginalizing the rest. But this solution is no panacea either. History has shown that such groups will have voluntary, or involuntary, leaks proportional to the size of the group.
But lets put aside these problems. Lets make believe we can keep secrets.
Lets pretend for a moment that the dubious claim that administrators don't
need to know how a vulnerability works in order to protect against it is
actually true. Have we solved the problem?
This solution also suffers from the problem that it assumes only people
within the privileged group are capable of finding vulnerabilities and
writing exploits, or that anyone else that is capable of these tasks will
only communicate with the group. This is a highly unlikely situation. A
large number of people have this capability, and not all of them will
agree with this policy, or have the same ethics.
Moreover, information on finding vulnerabilities and writing exploits is
readily available and is part of the open exchange in computer security
research. This information will not suddenly disappear, nor will it be
Second, we cannot stop the small number of malicious users with knowledge
of vulnerabilities or exploit tools from distributing them to other
Vulnerability information and exploit tools are normally embodied as
electronic documents. This allows the creation of copies at an
insignificant cost. Malicious users are beneficiaries of the revolution in
communications like the rest of us. They have efficient communication
channels (IRC, web sites, mailing lists, instant messaging, etc). They
also have a social structure based on trade, where vulnerability
information and exploits are treated as a commodity. Thus, a single
individual is capable of arming a large number of malicious users in a
matter of seconds.
SECURITY SCAPEGOATING.One proposed solution to this conundrum is to outlaw disclosure of vulnerability information and transfer of exploits to anyone but legitimate users of them. Once again -- putting aside the problem of
determining who is a legitimate user and who is not -- we still have the
problems of freedom of speech, globalization, and anonymity.
The solution would infringe on the freedom of speech afforded in many
places, although this is not an insurmountable problem. There are limits
to what one can say, especially if the specter of "national security" is
invoked. Such limits can also be legislated by industries, with enough
lobbying, as Professor Felten and others learned when they were threatened
by the recording industry under the DMCA.
For such a solution to have any teeth it would have to be implemented on a
worldwide basis. That may not be such a far-fetched idea, given the
Council of Europe's computer crime treaty, but it's not easily
accomplished in real life. Laws are pretty useless unless they are
actively enforced. The Internet and other technologies can provide a high
degree of anonymity for those that know how, and that knowledge is highly
valued by malicious users. If the unsuccessful searches for the authors of
many Internet worms and viruses are any indication, would-be law-breakers
would have little to worry about by exchanging vulnerability information
and exploits with other malicious users.
From these facts it should be obvious to most observers that attempting to
degrade an attacker's capability to execute the attack is a losing battle.
Instead we should focus our limited resources on denying would-be
attackers the opportunity to launch an attack, and on neutralizing
their motivations to attack.
Of course, ethical folks should try to disclose vulnerabilities and tools
in a responsible way. But just what is responsible in an open society
that values research and the open exchange of ideas is open to
interpretation and is different for each person.
While we don't yet have the technology to develop bug free software or
hardware, there are plenty of examples that demonstrate that a commitment
to develop a secure product throughout the design, implementation, and
deployment phases can dramatically reduce a malicious user's opportunity
to attack. It's high time for vendors of vulnerable products to clean up
their act and stop looking for scapegoats for their lousy products. Elias Levy is CTO of SecurityFocus, and the former moderator of the BUGTRAQ security mailing list.