Search for injected script code on the Windows Server for my ASP.NET site

Question

My site was probably hacked. I am finding script.js from bigcatsolutions.com in my page. It triggers a popup of an affiliate program. The script isn't on the page by default and I want to know how can I find where it was injected. The script sometimes injects other ad sites.

In chrome I see this:

The injected script code:

function addEvent(obj, eventName, func) {
    if (obj.attachEvent) {
        obj.attachEvent("on" + eventName, func);
    } else if (obj.addEventListener) {
        obj.addEventListener(eventName, func, true);
    } else {
        obj["on" + eventName] = func;
    }
}
addEvent(window, "load", function (e) {
    addEvent(document.body, "click", function (e) {
        if (document.cookie.indexOf("booknow") == -1) {
            params = 'width=800';
            params += ', height=600';
            params += ', top=50, left=50,scrollbars=yes';
            var w = window.open("http://booknowhalong.com/discount-news", 'window', params).blur();
            document.cookie = "booknow";
            window.focus();
        }
    });
})

My site is moved from my hosting company to Amazon EC2 Windows 2013 Server and still have the issues, so it means that the code still resides on the server somewhere. My site was build using ASP.ENT / C#.

Things I did:

• tried to search the original aspx and aspx.cs code files

Answer 1

Have you checked the IIS logs to see if they are hitting a specific page and injecting it there?

Do you load any data from a database? You could check in the tables and see if anything out of the ordinary appears there.

It is unlikely that the .aspx pages have actually been physically modified and even more unlikely that the DLL have been as .aspx.cs files are compiled in to your BIN folder as DLL's. The more likely scenario is that you have an unsecure page that a malicious site is injecting its script into. The other possible attack vector is that you have had malicious code via SQL injection and are loading it each time.