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February 1, 2017updated 02 Feb 2017 8:37am

Google blocks entire NHS network in a case of mistaken traffic identity

Reports have surfaced that Google has mistaken the entire NHS network for a cyber attack.

By Tom Ball

The entire NHS network has allegedly been blocked by Google, with the US search giant viewing traffic generated by the NHS network as a cyber-attack.

The NHS confirmed that its network had been disrupted, with 1.2 million employees impacted due to the restricted service.

News of the NHS block by Google broke via The Register, who were given an email reportedly from the NHS IT Department. It read:

“Google is intermittently blocking access due to the amount of traffic from NHS Trusts Nationally (This is not being blocked by the IT Department). This is causing Google to think it is suffering from a cyber-attack.”


“We are advising staff to use an alternative search engine i.e. Bing to bypass this problem.

“If you have ‘Chrome’ on your desktop the page will display correctly but if you ‘should’ get a CAPTCHA pop up, please follow the instructions to continue.”

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It seems that Google may be mistaking the entire NHS network for a DDoS cyber-attack, an attack which involves hackers battering the target with malicious traffic via hijacked computers linked in a botnet.

Additional reports have stated that Google are denying the blocking of the NHS network, which sits at odds with the disruption currently being experienced at trusts nationwide.


Google released a statement to CBR, refuting the claims made in initial reports.

“There are many reasons why users might see a CAPTCHA window when they do a Google search. Our systems are simply checking that searches are being carried out by humans and not by robots in order to keep web users safe. Once a user has filled out the CAPTCHA, they can continue to use Google as normal,” said a Google spokesperson.

Google went on to state that they were ‘satisfied that our systems are working correctly in this case; our systems are able to handle huge volumes of innocuous queries coming from one network. The tech giant said that it was not blocking the entire NHS network as reports suggested, instead giving the following as reasons as to why the NHS may have seen disruption on its network:

  • Users will sometimes see a message that says “Our systems have detected unusual traffic from your computer network” if it seems like a computer or phone on the network is sending automated traffic to Google;
  • Automated traffic could be things such as sending searches from a robot, computer program, automated service or search scraper. Or using software to send searches to Google to see how a website or webpage ranks on Google;
  • It could also be related to the use of a VPN browser plugin or program, or the presence of malware on a computer within the network which is sending automated searches to Google;
  • In most cases, users will see a CAPTCHA page – to continue using Google, users should type the CAPTCHA word into the box, to prove to Google that the user is a human and not a robot. Once the CAPTCHA has been entered correctly, the message will disappear, and the user will be able to access Google again.

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