Your business domain probably has some of these ports open

If you rely on TCP port 554, you'll probably want to do a bit of reconfiguration.

Last year, security researchers discovered a new version of the NAT Slipstream vulnerability that allowed hackers to deploy malicious scripts in order to bypass a website visitor's NAT firewall and access any TCP/UDP port on the visitor's internal network.

If this issue sounds vaguely familiar, it's because this isn't the first time it has come up. When the issue was first reported, Google released Chrome 87, which began blocking HTTP and HTTPS access to TCP ports 5060 and 5061. Then in January 2021 Google expanded their efforts, blocking HTTP, HTTPS, and FTP access to ports 69, 137, 161, 1719, 1720, 1723, and 6566.

Google has, in the past, also blocked port 554, but when they did so initially, they received push back from Enterprise users who asked that the port be unblocked. Google did so, but have now reversed course, and port 554 is once again on the blocked list.


Google is alone in blocking ports

It should also be noted that Google isn't alone. In addition to Chrome 89, Firefox 84+ and Apple's Safari browser are already blocking Port 554. So if you host a website on any of the ports mentioned above, you should reconfigure to allow visitors to continue to have unfettered access. Obviously, if you don't currently utilize that port there's nothing to do here.

If you're not sure, you will be soon enough, because you're apt to get complaints from users who can no longer access your site or whatever web-based application you're running that relies on it.


My perspective

Despite some back and forth on the matter, this appears to be the path forward. So kudos to Mozilla, Google and Apple for getting on the same page and putting a halt to the threat, even if it took a bit longer than usual for the major forces in the browser ecosystem to all wind up on the same page.


~ Steve Urkel might have said - "Did I do that?" ~


By Denis Wilson

Cybersecurity Expert, Small Business Technology Consultant, Managed Services Provider, Managed IT Support

Thanks for reading this short post. For more tips on thriving with small business technology, check out the other blog posts at DWPIA Blogs. You can also find me on LinkedIn, Facebook, and Twitter

I am also a published author and speaker on cloud computing, work@home, and cybersecurity. I work extensively with business and professional associations to provide small business technology education programs.


Contact me if you would like me to speak to your association