Security News > 2021 > March > Google Chrome to block port 554 to stop NAT Slipstreaming attacks

Google Chrome will block the browser's access to TCP port 554 to protect against attacks using the NAT Slipstreaming 2.0 vulnerability.
Last year, security researchers disclosed a new version of the NAT Slipstreaming vulnerability that allows malicious scripts to bypass a website visitor's NAT firewall and access any TCP/UDP port on the visitor's internal network.
In January 2021, Google blocked HTTP, HTTPS, and FTP access to an additional seven ports: ports 69, 137, 161, 1719, 1720, 1723, and 6566.
In the past, Google also blocked port 554 but removed the block after complaints from enterprise users.
Google and Safari developers are also discussing blocking access to port 10080, which Firefox already blocks, but are hesitant due to legitimate web browser requests to that port.
Once a port is blocked, when a user attempts to connect to it, users are shown an error message stating 'ERR UNSAFE PORT.'.
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