Every time they say "17 security agencies all agree" I hear "climate scientists are unanimous that man-made global warming is a fact".
Every time I hear them talk about "17 security agencies", I think to myself "may as well go for as big a number as possible...sounds impressive." Technically, this is just semantics since the ODNI's role is to organize and coordinate the efforts of the other 16 IC agencies. Further, there never was 17 distinct agencies that investigated Russia as being behind hacks and independently made a conclusion about it. However, the Office of the Director of National Intelligence speaks on behalf of these group so therefore, there was 17 security agencies who all agree. See how easy it is to make the number seem a tad more impressive? How many actually had anything to do with it? Three...CIA, NSA and FBI.