China-backed hackers have been spotted exploiting a security flaw in Internet software. According to Microsoft, cyber groups affiliated to China and Iran have launched assaults using the Log4j weakness. It’s one of the most serious cybersecurity risks to emerge in years, according to researchers, and it might allow for devastating strikes. According to cybersecurity firms and Microsoft Corp., hackers linked to China and other countries are among an increasing number of cyberattackers attempting to exploit a widespread and severe weakness in computer server software. Cybersecurity researchers say it is one of the most dire cybersecurity threats to emerge in years…