Android Stock Browser downloads file immediately after start

Android 4.4.2 Kitkat Stock Browser If I start it or open new tab, downloading of apk file (xb_client_blah-blah-blah.apk) from site no.stepfaster.com immediately starts instead of opening page which is set as default. Obviously some malware fixed Browser's config. Which file and how to fix this? No root. Browser was stopped and cache cleaned several time. Nothing was installed before this. The mentioned site contains AdSDK apk-files.