Over the past several weeks, a hacker group identified as APT3 by security firm FireEye has used the vulnerability to attack organizations from the aerospace, defense, construction, engineering, technology, telecommunications and transportation industries.
The attackers use the exploit to install a backdoor known as SHOTPUT or CookieCutter and then move through the organization's network, using other techniques and exploits to compromise additional systems.
In order to be protected against this vulnerability, which is tracked as CVE-2015-3113, Adobe advises users to update to the newly released Flash Player versions: 184.108.40.206 for Windows and Mac, 220.127.116.118 for Linux, and 18.104.22.1686 for the extended support release.
The Flash Player plug-in that's installed by default with Google Chrome and Internet Explorer on Windows 8.x will be automatically updated. Flash Player users on Windows or Mac who have selected "allow Adobe to install updates" will also get the update automatically.
APT3 is a sophisticated group known for using other zero-day browser-based exploits in the past for Internet Explorer, Firefox and Flash Player, according to FireEye. The group also uses custom backdoors and often changes command-and-control infrastructure, making it hard for researchers to track its activity.