The Winter Vivern APT group has been targeting a zero day XSS vulnerability in the Roundcube webmail server in recent weeks.
Fixes for both the Zoho and Fortinet vulnerabilities have been available since last year.
While the APT has targeted dozens of organizations in Taiwan, researchers with Microsoft warn that its tactics could easily be used in campaigns in other areas.
The China-based hacking group has targeted ministries of foreign affairs across the Americas with updated malware called Graphican.
A "powerful" backdoor has been uncovered in highly targeted, intel-gathering APT attacks.