I have the issue on my Nexus 5 mobile device using Chrome browser. I got the virus most likely from ebay's adware. I am very confident the issue relates to ebay as I visited the site for the first time yesterday on my phone. Normally i just use the ebay app. But i was responding to an email from a seller and was taken to the ebay website. Since then i have been getting his pop up message whenever i use my chrome browser on my phone. I cannot replicate this issue on my PC. I deleted all my cookies but to no avail. I have not downloaded any apps recently from the app store. Nor have i ever download apps from anywhere else other than the play store. So a malicious app is not the issue. This issue, once fixed, will ensure i will never visit ebay store web site, only will use the ebay app.

Regards,

 Eamonn

I have the same issue with the same warning on ebay, I use Safari (version 5.0.6), and it all started on 21st January.  I did all the usual - Resetting Safari, instigate virus scan et al, but the problem persisted.

I telephoned Customer Services, only to be told that it would be a problem with my computer, and that ebay were not aware of such an issue.  Having searched various chatrooms, I think I can safely say, we are not alone.  

Come on ebay, sort it out! 

It seems to be a trick to get you downloading an infected apk file. I could find this:

http://die-it-werkstatt.de/android-malware-warning-your-phone-has-13-virus-play-google-android-secur...