Theft of secrets is nothing new. Nor is it new to publicize stolen secrets with hopes of
influencing (or instigating) leadership changes in government. So the theft of
confidential information being stored by the Democratic National Committee (DNC) is part
of a long tradition, albeit perpetrated in a new venue: cyberspace. This new venue,
however, offers considerable benefits to attackers:
Remote Access. An attacker can work any time of day or night,
which not only helps evade detection but also allows attacks to proceed over an
extended period. Moreover, a skilled attacker is able to remove evidence of the
attack. Electronically exfiltrating secrets, for example, does not require
removing or altering anything physical and thus does not have a noticeable
effect. In addition, even if a cyberattack is detected, attribution is
difficult. Consequently, deterrence through accountability is not an effective
defense. Even when attribution is possible, knowledge of who perpetrated some
attack is actionable only if some law enforcement regime has jurisdiction over
the attacker. By working from abroad, an attacker often can use jurisdiction to
Speed. A large part of the cost for perpetrating an attack in
cyberspace is the effort to penetrate the target computing system. Once that
system has been compromised, existing high-speed networking enables large
amounts of information to be rapidly transmitted back to the attacker. Thus, an
attacker's exposure is small, even to exfiltrate large numbers of documents.
And the additional effort and exposure to steal further information from the
target is inconsequential. So attackers are not forced to decide before or
during an attack which individual documents to steal—it's just as easy to steal
everything and digest it later, on the attacker's own system.
The DNC attacks were successful for two reasons.
1) Passwords are not a secure way to authenticate whether somebody should be
granted access to a system. They are easily guessed or stolen.
2) Commercially available computing systems are rife with vulnerabilities. They,
in turn, can allow a program running under the auspices of one user to access
data that should be accessible only to other users.
Yet we do know how to do better. Such systems, however, are less convenient to use and
more expensive to develop. Better authentication requires that users engage in more
complicated protocols, and do so more often. Elimination of system vulnerabilities
requires developers to expend more effort in design and testing. System developers also
would have to eschew the complicated features users favor and, instead, build only those
features that are simple enough for all behaviors to be anticipated and analyzed. And
tighter access polices would have to be formulated individually for each object.
Higher cost? Less convenience? These sacrifices require some value proposition. But
today it is hard to justify making those sacrifices for security:
• The need for better security is not well understood by those who make
procurement decisions. Institutions are hesitant to broadcast that they have
been attacked successfully, since that knowledge detracts from their image.
Moreover, information about threats is typically held close by those who know.
So decisions to make sacrifices must be made without an accurate picture of the
risks that come from failing to make those sacrifices.
• Good metrics for system security do not exist, and there are technical reasons
to believe they cannot exist. Sacrifices for security must then be rationalized
by appeal to indirect measures, such as the reputation of the software producer
or the development process that was employed. By their nature, indirect
measures cannot give a strong guarantee of security.
So system producers, purchasers, and users have no way to justify the costs—be it
inconvenience or other forms of expense—for system security. Furthermore, existing law
provides the wrong incentives to software producers, if system security is what we seek:
producers are not legally accountable to their customers or to anyone else when a system
they sell has flaws that make that system vulnerable to attack. We might change the law.
To do so, however, means selecting some mix of taxpayers, users, or investors to bear
the burden of higher costs and/or reduced functionality.
Help from Cryptography?
Without knowledge of the decryption key, nothing can be learned about the contents of an
encrypted document. So cryptography transforms the implementation of confidentiality for
a set of documents into the much simpler problem of controlling confidentiality and
access to a decryption key. Today's commercial computing systems are capable of storing
documents on disk in encrypted form, though this feature is rarely used. When encryption
is not in use, an attacker masquerading as some user U would likely
have free reign not only to access any document that U can view but
also any document that any other user was authorized to view. Encrypt all the documents
and such an attacker would only be able to view the documents that U is
authorized to view plus, in the worst case by exploiting vulnerabilities, the few
documents being accessed by other users while the attack is in progress.
Interception of messages in transit on a network affords attackers a second means for
stealing secrets. But if message contents are encrypted, then interception reveals less.
However, even this form of surveillance can reveal useful information, because the
destination of a message will not be encrypted—a destination address must remain
intelligible, so it can be read by network switches that implement message routing.
Knowledge of a message destination might reveal the identity of groups that wished their
involvement to be secret. On balance, however, encryption for data in motion has an
enormous pay-off for protecting the confidentiality of information.
Given the improved security that results from encryption for data at rest and for data
in motion, we might hope that press attention from attacks would prompt wary users to
insist on email and file system encryption, visionary system administrators to be
proactive and activate those features on systems they manage, and/or well-meaning
software developers to make encryption the default for systems they distribute. Hope
springs eternal. The DNC computing system compromise was not the first highly-publicized
confidentiality breach. It was not even the first confidentiality breach to have
national security implications. For example, the attack of the U.S. Government Office of
Personal Management (OPM) around March 2014 stole identify data for all who hold
Regulation is a means to promote action for greater societal benefit when neither common
sense nor the market provide the incentives. So it is tempting to contemplate laws that
would incentivize encryption—at least for certain kinds of information. There is, of
course, the problem of characterizing what information should be covered by such a law.
But encryption also raises a far more contentious issue, which puts two societal goals
in conflict: surveillance versus security.
Surveillance provides a cost-effective approach to defense for any collection of assets
in an asymmetric setting. It enables the defender to anticipate a given attack.
Forewarned, the defender can then undertake modest pre-emptive action and/or deploy
limited defenses that temporarily protect the threatened asset from the expected attack.
The total cost of this surveillance-based approach to defense is significantly lower
than the total cost to deploy individual defenses for every asset that might be
attacked—the cost of a surveillance-based defense is the cost of surveillance (which is
proportional to the number of attackers or to the number of sensors that provide
sufficient coverage) plus the cost of defenses that can be proactively deployed in
response to an alarm.
The rationale for surveillance-based defense is not only compelling, but there is ample
evidence that the approach is widely used in practice. The Snowden disclosures revealed
that, in order to anticipate terrorist attacks, the U.S. Intelligence Community has been
intercepting Internet messages in transit to international destinations. And cell phones
are increasingly seen by law enforcement as a source of valuable information, not only
about an individual's past activities—useful for forensics—but also about planned
activities and collaborators.
Encryption, however, impedes surveillance and impedes access to information stored on
devices procured using search warrants. So encryption undermines what has become an
important approach to U.S. defense, hence to U.S. security. Calls for wide-spread
deployment of encryption have been characterized as “Going Dark” when discussing any
transition to a regime where file systems and network traffic is encrypted. So we see
legislative proposals (e.g., Burr-Feinstein
) advocating that encryption mandates be accompanied by a mandate to provide some
form of “back door” for decrypting the encrypted information, and we see Federal
officials (e.g., FBI director James Comey
) advocating that access to such a “back door” be controlled by some body that
can be trusted to make sensible trade-offs between the rights of individuals and the
security of our nation.
To some, putting trust in a surveillance-authorizing body is problematic. Moreover,
transparency for review of that body's decisions might not be an option here, since
surveillance often becomes ineffective when the target has been warned. So we could be
forced to delegate decisions about surveillance to a body without the benefit of
deterrence through accountability that oversight provides. Information encrypted by the
DNC would be an interesting gedankenexperiment, given the strong
incentive for a political party in power to preserve the status quo. Encryption here
might have protected DNC secrets from a foreign adversary but not from the domestic
Of course, there already are various government bodies that U.S. citizens trust to
operate in secret, making decisions where the rights of individuals are in tension with
greater societal good. The above “back door” argument raises another class of concerns,
too, though. Is it technologically feasible to ensure that a surveillance-authorizing
body is the sole principal with access through some “back door”? A long history of
failures suggests that skepticism is justified. So we are unlikely to succeed in
discharging one of the fundamental requirements for “back door” access to encrypted
content. Regulation that mandates encryption becomes less compelling to encryption
advocates if that regulation also must mandate a “back door.”
The Bigger Picture
Absolute security is widely understood to be a fool's errand; system security is best
seen as relative. We deem a system to be secure provided it enforces some specified
policies, even while being attacked by some class of adversaries. Examples of policies
1) confidential information is not disclosed to unauthorized users,
2) information is not changed by unauthorized users.
3) requests for service are handled within T seconds.
Classes of adversaries often are characterized in terms of their resources or technical
capabilities. We therefore should be regarding nation-state intelligence agencies,
domestic activist groups, local organized crime, and college undergraduates as being
distinct classes, since each would have access to different levels of resources. The
theft of secrets from the DNC computing system violated policy (1) above, as did the OPM
breach. In both of these cases, it would seem reasonable to have anticipated a
nation-state adversary. Sony, whose compromise in Fall 2014 revealed sensitive
enterprise information, might justifiably have been preparing to defend only against
weaker adversaries. But those defenses might not have sufficed if, as reported in the
press, North Korea was behind the attacks.Footnote
Deciding on an appropriate defense is difficult when deciding on potential
adversaries is difficult.
In addition, as the discussion of cryptography reveals, enhanced security of computing
systems can be in tension with other values that governments deem important. So there
are some aspects of improved cybersecurity that a government is unlikely to promote.
Here is a case where the government might not be willing to create incentives when each
individual's behaviors fails the greater societal good.
Finally, as should be clear, the DNC attacks, while a good reason to start a discussion,
could easily lead us astray. That campaign secrets could destabilize a presidential
election is beside the point (and is something that the U.S. has reputed to have done to others, tooFootnote
). In seeking an approach to remedies, we should focus on remedies that apply to
a broad range of institutions. As long as our systems are used by ordinary people, then
we should authenticate users in ways that are difficult for an attacker to circumvent by
fooling the victim into abusing authority. And as long as our systems are used to store
information, then cryptography should be deployed to help protect data at rest as well
as data in motion.