For several years law firms have been a key target for hackers seeking to obtain confidential information about initial public offerings, intellectual property and M&A deals, claim cybersecurity consultants, but rarely does word about specific attacks become public.

On Tuesday, Crain’s Chicago Business reported that 48 top firms, most of which appear in the Am Law 100 rankings, were targeted recently by a Russian hacker living in Ukraine seeking to trade on M&A information stolen from law firms.