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

(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.

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 It's true that it's easy for an attacker to hide who he is in cyberspace. We are unable toidentify 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.

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