"It’s common for the initial forensic analysis to be conducted by outside firms like CrowdStrike, and once that data has been copied, there’s often little need to copy it again. BuzzFeed described the FBI’s lack of interest in the DNC’s server as unusual, citing a number of response firms that preferred not to be named. But that’s not a unanimous opinion, and two experts contacted by The Verge disagreed that it was unusual.

“This is normal practice,” says Matt Tait, founder and CEO of Capital Alpha Security. “In cases like this, the onus for digital forensics is on the third-party contracted by the company that's calling in the incident response team, in this case CrowdStrike.”

It’s part of a long-standing division of labor between private firms and law enforcement, in which incident response firms handle the initial analysis and network cleanup, leaving broader legal questions to law enforcement. That division of labor saves time, but it also protects companies from what could potentially be seen as an invasion of privacy. Turning over a company’s entire network to a law enforcement agency can be an awkward proposition, particularly before the nature of the compromise is clear.

That’s particularly true for the DNC, since the FBI was actively investigating Hillary Clinton for mishandling classified information at the time — and it’s clear the agency had no reservations about searching for evidence of those crimes in unrelated cases. Similar awkwardness is common at corporate breaches, and the result has given incident response firms like CrowdStrike a persistent business as intermediaries between companies and law enforcement.

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Once incident response has been conducted, the crucial evidence can be handed over directly to officials without politically tricky questions of broader access. We don’t know exactly what CrowdStrike handed over (the company declined to comment), but that data can range from full disk images to an edited digest of suspicious files and logged connections. If CrowdStrike did image the server, any subsequent analysis would simply be confirming that the firm hadn’t screwed up.

Law enforcement groups sometimes do double-check that data, but it’s unlikely to change the attribution itself. Even if CrowdStrike wanted to skew the results toward a particular party, the FBI would be able to check their work against data pulled directly from the network. “The IC would certainly be able to check the malware and associated technical data recovered from the DNC network themselves,” says Tait. “The FBI may be reliant on CrowdStrike to find malware on the DNC network, but they are not beholden to CrowdStrike's analysis.”

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There’s also reason to think CrowdStrike is simply better at this kind of ground-level forensics than the FBI. The bureau has long struggled to retain cybersecurity talent, losing a steady stream of agents to more lucrative positions at a long list of private-sector security companies. That list includes CrowdStrike itself: the company’s services branch is run by Shawn Henry, an FBI lifer who many credit with the bureau’s recent focus on cybersecurity. The result is a persistent brain drain, and a valid reason for the FBI to focus its energy on the higher-level problems of attribution. If the FBI had decided to duplicate CrowdStrike’s work, it’s not clear they could have done a better job."

https://www.theverge.com/2017/1/5/14178806/fbi-dnc-hack-serv...