Why proving the source of a cyberattack is so damn difficult

 State dept. '100% certain' about Russian hack
 State dept. '100% certain' about Russian hack

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State dept. '100% certain' about Russian hack 02:13

Story highlights

  • Bruce Schneier: It's one thing for government to know who committed a cyberattack
  • It's quite another for it to convince the public who attacked, Schneier says

Bruce Schneier is a security technologist and chief technology officer of Resilient Systems Inc. His latest book is "Data and Goliath: The Hidden Battles to Collect Your Data and Control Your World." He blogs at schneier.com and tweets @schneierblog. The opinions expressed in this commentary are his.

(CNN)President Barack Obama's public accusation of Russia as the source of the hacks in the US presidential election and the leaking of sensitive emails through WikiLeaks and other sources has opened up a debate on what constitutes sufficient evidence to attribute an attack in cyberspace. The answer is both complicated and inherently tied up in political considerations.

Bruce Schneier
The administration is balancing political considerations and the inherent secrecy of electronic espionage with the need to justify its actions to the public. These issues will continue to plague us as more international conflict plays out in cyberspace.
It's true that it's easy for an attacker to hide who he is in cyberspace. We are unable to identify particular pieces of hardware and software around the world positively. We can't verify the identity of someone sitting in front of a keyboard through computer data alone. Internet data packets don't come with return addresses, and it's easy for attackers to disguise their origins. For decades, hackers have used techniques such as jump hosts, VPNs, Tor and open relays to obscure their origin, and in many cases they work. I'm sure that many national intelligence agencies route their attacks through China, simply because everyone knows lots of attacks come from China.
On the other hand, there are techniques that can identify attackers with varying degrees of precision. It's rarely just one thing, and you'll often hear the term "constellation of evidence" to describe how a particular attacker is identified. It's analogous to traditional detective work. Investigators collect clues and piece them together with known mode of operations. They look for elements that resemble other attacks and elements that are anomalies. The clues might involve ones and zeros, but the techniques go back to Sir Arthur Conan Doyle.
The University of Toronto-based organization Citizen Lab routinely attributes attacks against the computers of activists and dissidents to particular Third World governments. It took months to identify China as the source of the 2012 attacks against The New York Times. While it was uncontroversial to say that Russia was the source of a cyberattack against Estonia in 2007, no one knew if those attacks were authorized by the Russian government -- until the attackers explained themselves. And it was the Internet security company CrowdStrike, which first attributed the attacks against the Democratic National Committee to Russian intelligence agencies in June, based on multiple pieces of evidence gathered from its forensic investigation.
Attribution is easier if you are monitoring broad swaths of the Internet. This gives the National Security Agency a singular advantage in the attribution game. The problem, of course, is that the NSA doesn't want to publish what it knows.
Regardless of what the government knows and how it knows it, the decision of whether to make attribution evidence public is another matter. When Sony was attacked, many security experts -- myself included -- were skeptical of both the government's attribution claims and the flimsy evidence associated with it. I only became convinced when The New York Times ran a story about the government's attribution, which talked about both secret evidence inside the NSA and human intelligence assets inside North Korea. In contrast, when the Office of Personnel Management was breached in 2015, the US government decided not to accuse China publicly, either because it didn't want to escalate the political situation or because it didn't want to reveal any secret evidence.
The Obama administration has been more public about its evidence in the DNC case, but it has not been entirely public.
It's one thing for the government to know who attacked it. It's quite another for it to convince the public who attacked it. As attribution increasingly relies on secret evidence -- as it did with North Korea's attack of Sony in 2014 and almost certainly does regarding Russia and the previous election -- the government is going to have to face the choice of making previously secret evidence public and burning sources and methods, or keeping it secret and facing perfectly reasonable skepticism.
If the government is going to take public action against a cyberattack, it needs to make its evidence public. But releasing secret evidence might get people killed, and it would make any future confidentiality assurances we make to human sources completely non-credible. This problem isn't going away; secrecy helps the intelligence community, but it wounds our democracy.
The constellation of evidence attributing the attacks against the DNC, and subsequent release of information, is comprehensive. It's possible that there was more than one attack. It's possible that someone not associated with Russia leaked the information to WikiLeaks, although we have no idea where that someone else would have obtained the information. We know that the Russian actors who hacked the DNC -- both the FSB, Russia's principal security agency, and the GRU, Russia's military intelligence unit -- are also attacking other political networks around the world.
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In the end, though, attribution comes down to whom you believe. When Citizen Lab writes a report outlining how a United Arab Emirates human rights defender was targeted with a cyberattack, we have no trouble believing that it was the UAE government. When Google identifies China as the source of attacks against Gmail users, we believe it just as easily.
Obama decided not to make the accusation public before the election so as not to be seen as influencing the election. Now, afterward, there are political implications in accepting that Russia hacked the DNC in an attempt to influence the US presidential election. But no amount of evidence can convince the inconvincible.
The most important thing we can do right now is deter any country from trying this sort of thing in the future, and the political nature of the issue makes that harder. Right now, we've told the world that others can get away with manipulating our election process as long as they can keep their efforts secret until after one side wins. Obama has promised both secret retaliations and public ones. We need to hope they're enough.