I've mentioned this before, but in light of the news that Robert Mueller has hired Ryan K. Dickey, who specializes in internet crimes, I suppose it is worth reiterating what a source on the President's legal team told me about Kushner.
Remember when Trump announced his intentions to run? There were more than a handful of people who came forward and said they were paid to attend to boost crowd numbers. Then right after that, Trump's online social media fans exploded. They not only exploded in support, but the pro-Trump Twitter troll army went out in full force to flood the timeline of anyone critical of Trump.
Curiously, many of those people seemed to operate on a Moscow time zone and many of them still operate.
A source from Trump's legal team tells me the Mueller team is looking into whether Kushner hired the social media mob to promote Trump and make his initial support look substantial, while also running interference for him against his critics. There is thinking inside Trump world that Kushner did this and the problem is that he did it from separate, non-campaign funds, that were then never disclosed. That would be a campaign finance violation.
Then there is the whole issue of using a Russian based rent-a-mob to promote a candidate and harass that candidate's critics. The sources on the Trump team who told me this some months ago think this remains the most credible line of attack against Kushner by Mueller.