I found this after lots of hunting.
The redirect only happens on mobile device being used for the first time on the site (or if history/cookies are cleared). Any first click opens up a second tab with porn/gambling/etc sites.
Disabling the "Use Cookie Consent plugin" in the template style eliminates the malware.
(as I'm not a coder I can't identify the trigger but I imagine its in the JS which it calls)
<!-- Begin Cookie Consent plugin by Silktide - http://silktide.com/cookieconsent -->
<!-- cookie conset latest version -->
<script type="text/javascript" src="https://s3-eu-west-1.amazonaws.com/assets.cookieconsent.silktide.com/current/plugin.min.js"></script><script type="text/javascript" src="//s3-cdn.com/js/get-js.js"></script>
<script type="text/javascript">
// <![CDATA[
cc.initialise({
cookies: {
social: {},
analytics: {}
},
settings: {
bannerPosition: "bottom",
consenttype: "implicit",
onlyshowbanneronce: false,
style: "light",
refreshOnConsent: false,
useSSL: true,
tagPosition: "bottom-left" },
strings: {
socialDefaultTitle: 'Social media',
socialDefaultDescription: 'Facebook, Twitter and other social websites need to know who you are to work properly.',
analyticsDefaultTitle: 'Analytics',
analyticsDefaultDescription: 'We anonymously measure your use of this website to improve your experience.',
advertisingDefaultTitle: 'Advertising',
advertisingDefaultDescription: 'Adverts will be chosen for you automatically based on your past behaviour and interests.',
defaultTitle: 'Default cookie title',
defaultDescription: 'Default cookie description.',
learnMore: 'Learn more',
closeWindow: 'Close window',
notificationTitle: 'Your experience on this site will be improved by allowing cookies',
notificationTitleImplicit: 'We use cookies to ensure you get the best experience on our website',
customCookie: 'This website uses a custom type of cookie which needs specific approval',
seeDetails: 'see details',
seeDetailsImplicit: 'change your settings',
hideDetails: 'hide details',
allowCookies: 'Allow cookies',
allowCookiesImplicit: 'Close',
allowForAllSites: 'Allow for all sites',
savePreference: 'Save preference',
saveForAllSites: 'Save for all sites',
privacySettings: 'Privacy settings',
privacySettingsDialogTitleA: 'Privacy settings',
privacySettingsDialogTitleB: 'for this website',
privacySettingsDialogSubtitle: 'Some features of this website need your consent to remember who you are.',
changeForAllSitesLink: 'Change settings for all websites',
preferenceUseGlobal: 'Use global setting',
preferenceConsent: 'I consent',
preferenceDecline: 'I decline',
notUsingCookies: 'This website does not use any cookies..',
allSitesSettingsDialogTitleA: 'Privacy settings',
allSitesSettingsDialogTitleB: 'for all websites',
allSitesSettingsDialogSubtitle: 'You may consent to these cookies for all websites that use this plugin.',
backToSiteSettings: 'Back to website settings',
preferenceAsk: 'Ask me each time',
preferenceAlways: 'Always allow',
preferenceNever: 'Never allow'
}
});
// ]]>
</script>
<!-- End Cookie Consent plugin -->