In a study of 268 senior marketing decision-makers at mid-sized UK brands, carried out by brand protection solution Project Sunblock, nearly four in five admitted blindness to potential bot traffic.

Respondents estimated that bot traffic was costing them between £10-£15,000 each year.

Andrew Goode, COO of Project Sunblock said: “Botnets are already surprisingly sophisticated and will only become more potent in time. There are many pieces of malware used to infect PCs which are used to create fake traffic and then sold on to publishers through ad exchanges, and some of the bots are almost indestructible.

“It’s surprising that despite relatively high awareness of the issue of bots, there are still relatively few advertisers who have taken action to fight them.”