https://www.vice.com/en_us/article/5dbk5q/annoying-linkedin-networkers-actually-russian-hackers-spreading-zero-days-google-says

Most LinkedIn spam is just annoying. But new research from Google suggests some of it was outright dangerous: Russian government hackers targeted European government officials with LinkedIn messages that contained malicious links designed to exploit unknown vulnerabilities in Windows and iOS, according to Google's report. 

Google's Threat Analysis Group published new research on Wednesday, detailing several hacking campaigns leveraging a series of zero-day exploits, meaning hacks that rely on vulnerabilities that are unknown to the developers of the targeted software.