Here a nice explanation of the vulnerability: <a href="https:&#x2F;&#x2F;blog.exodusintel.com&#x2F;2016&#x2F;02&#x2F;10&#x2F;firewall-hacking&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.exodusintel.com&#x2F;2016&#x2F;02&#x2F;10&#x2F;firewall-hacking&#x2F;</a><p>There is also a Snort signature to detect attempts to exploit this vulnerability.