Android users have been put on alert after malware was found pre-installed on hundreds of phones straight out of the box.
The adware, dubbed Cosiloon, was discovered by researchers from cybersecurity firm Avast.
Security experts said the malware was found on hundreds of Android phones with owners in the UK, US, Germany, Italy and Russia among those affected.
The adware creates an overlay to display an annoying advert over a webpage within the users’ browser.
Thousands of smartphone owners are affected – in the past month alone Avast discovered the Cosiloon adware on around 18,000 devices.
Avast reported the findings of their research to Google who have ”taken steps to mitigate the malicious capabilities of many app variants on several device models, using internally developed techniques.”
Avast said the malware was discovered on budget smartphones with the majority of them not certified by Google.
Researchers said the adware was discovered on phones made by manufacturers such as Archos, ZTE and Pretigio.
In a blog post outlining the threat, Avast said: “Several hundred different devices are affected.
“The affected devices usually sport a Mediatek chipset and are mostly low cost tablets.”