Following news of the Deutsche Telekom malware cyber-assault earlier this week knocking 900,000 customers offline, 100,000 Post Office and 'some' TalkTalk customers have also had their internet access cut by an attack targeting certain types of routers.
Several models of router are vulnerable to the latest hack including the Zyxel AMG1302, used by the Post Office, and which they advised their customers to reboot to ensure the latest updated software.
TalkTalk's D-Link DSL-3780 routers were also affected, but the company says these are only used by a small percentage of its customers.
The hack involves the Mirai worm attacking Linux-based operating systems, and follows the cyber-assault last week on several of the world's leading websites, including Spotify, Twitter and Reddit via their Dyn systems. The BBC was also affected via third suppliers using Dyn online directories.
Security analysts believe the hack used the 'internet of things' to launch the assault, instigating a DDoS in a global event involving tens of millions of internet addresses, and exploiting devices from Chinese manufacturers with easy-to-guess usernames and passwords that cannot be changed by the user.
This internet infrastructure vulnerability has frustrated many in the industry, including Salesforce's head of security Jeff Jarmoc, who tweeted, "In a relatively short time we've taken a system built to resist destruction by nuclear weapons and made it vulnerable to toasters".