Russia is after secret files in the US court system, according to reports this week—and its hackers appear to have reached at least some of them. Last week, news broke of a successful cyberattack against the decades-old US court filing system. Called Case Management/Electronic Case Files (CM/ECF), courts use the system to file and maintain documentation for legal cases around the country, which in turn can be accessed through a public portal called PACER. The attack happened as early ago as the first week of July, and possibly before that. Now, investigators say that Russia is at least partly responsible for the hack, which they described in the New York Times as a multi-year effort to compromise the system. What would Russian hackers be looking for? Many court documents are accessible…