Adam Raymond of New York Magazine explains the CrowdStrike connection in an analysis piece here: Questions About the Trump-Zelensky Memo, Answered
CrowdStrike is a U.S.-based cybersecurity firm that the Democratic National Committee hired to look into hacks on its servers. The firm determined that the attack originated from Russian government hackers. In his comments to Zelensky, Trump appeared to be referencing a conspiracy theory that accuses CrowdStrike of participating in a cover-up by helping the DNC hide that the hack was an inside job. According to CyberScoop, this is a common right-wing conspiracy and easy to debunk.
Essentially, it seems that Trump believes a conspiracy theory that the 2016 hack of the DNC email servers was an inside job and that CrowdStrike helped to cover it up and then hid the incriminating servers in Ukraine, since the co-founder of CrowdStrike is Ukrainian.
The linked article on cyberscoop explains this theory in more detail: Why did President Trump mention CrowdStrike to the Ukrainian president?
It appears that Trump asked Zelenskiy to search for a server linked with the 2016 breach of the Democratic National Committee (DNC) — an incident which California-based CrowdStrike helped to investigate.
Trump has long alleged a DNC server is “missing,” a theory which appears to be based on a conspiracy theory peddled in right-wing circles that CrowdStrike was involved in a cover-up of the DNC breach.
But in reality, there are no physical machines linked with the DNC breach that are actually missing. Instead of one server, there were actually more than 140 servers decommissioned by the DNC in June 2016, many of them cloud-based.
The theory was amplified when Trump adviser Roger Stone’s legal team alleged the 2016 hack was an inside job and that CrowdStrike tampered with the evidence to pin the activity on Russian hackers.
This is not the first time Trump has brought up the missing server conspiracy theory — he raised similar questions during his press conference with Russian President Vladimir Putin in July last year.
“You have groups that are wondering why the FBI never took the server,” Trump said last year. “Why didn’t they take the server? Where is the server, I want to know, and what is the server saying?”