Похоже, что вы можете обнаружить некоторые из них в Firefox, используя javascript, вот статья:
http://jeremiahgrossman.blogspot.com/2006/08/i-know-what-youve-got-firefox.html
и еще один:
http://ha.ckers.org/blog/20060823/detecting-firefox-extentions/
вот как это обнаружено:
// popular extensions.
var e = {
"Adblock Plus" : "chrome://adblockplus/skin/adblockplus.png",
"Auto Copy" : "chrome://autocopy/skin/autocopy.png",
"ColorZilla" : "chrome://colorzilla/skin/logo.png",
"Customize Google" : "chrome://customizegoogle/skin/32x32.png",
"DownThemAll!" : "chrome://dta/content/immagini/icon.png",
"Faster Fox" : "chrome://fasterfox/skin/icon.png",
"Flash Block" : "chrome://flashblock/skin/flash-on-24.png",
"FlashGot" : "chrome://flashgot/skin/icon32.png",
"Forecastfox" : "chrome://forecastfox/skin/images/icon.png",
"Google Toolbar" : "chrome://google-toolbar/skin/icon.png",
"Greasemonkey" : "chrome://greasemonkey/content/status_on.gif",
"IE Tab" : "chrome://ietab/skin/ietab-button-ie16.png",
"IE View" : "chrome://ieview/skin/ieview-icon.png",
"JS View" : "chrome://jsview/skin/jsview.gif",
"Live HTTP Headers" : "chrome://livehttpheaders/skin/img/Logo.png",
"MeasureIt" : "chrome://measureit/skin/measureit.png",
"SEO For Firefox" : "chrome://seo4firefox/content/icon32.png",
"SEOpen" : "chrome://seopen/skin/seopen.png",
"Search Status" : "chrome://searchstatus/skin/cax10.png",
"Server Switcher" : "chrome://switcher/skin/icon.png",
"StumbleUpon" : "chrome://stumbleupon/content/skin/logo32.png",
"Tab Mix Plus" : "chrome://tabmixplus/skin/tmp.png",
"Torrent-Search Toolbar" : "chrome://torrent-search/skin/v.png",
"User Agent Switcher" : "chrome://useragentswitcher/content/logo.png",
"View Source With" : "chrome://viewsourcewith/skin/ff/tb16.png",
"Web Developer" : "chrome://webdeveloper/content/images/logo.png",
"Unhide Passwords" : "chrome://unhidepw/skin/unhidepw.png",
"UrlParams" : "chrome://urlparams/skin/urlparams32.png",
"NewsFox" : "chrome://newsfox/skin/images/home.png",
"Add N Edit Cookies" : "chrome://addneditcookies/skin/images/anec32.png",
"GTDGmail" : "chrome://gtdgmail/content/gtd_lineitem.png",
"QuickJava" : "chrome://quickjava/content/js.png",
"Adblock Filterset.G Updater" : "chrome://unplug/skin/unplug.png",
"BBCode" : "chrome://bbcode/skin/bbcode.png",
"BugMeNot" : "chrome://bugmenot/skin/bugmenot.png",
"ConQuery" : "chrome://conquery/skin/conquery.png",
"Download Manager Tweak" : "chrome://downloadmgr/skin/downloadIcon.png",
"Extended Cookie Manager" : "chrome://xcm/content/allowed.png",
"FireBug" : "chrome://firebug/content/firebug32.png",
"FoxyTunes" : "chrome://foxytunes/skin/logo.png",
"MR Tech Disable XPI Install Delay" : "chrome://disable_xpi_delay/content/icon.png",
"SessionSaver .2" : "chrome://sessionsaver/content/ss.png",
"spooFX" : "chrome://spoofx/skin/main/spoofx.png",
"Statusbar Clock" : "chrome://timestatus/skin/icon.png",
"Torbutton" : "chrome://torbutton/skin/bigbutton_gr.png",
"UnPlug" : "chrome://unplug/skin/unplug.png",
"View Source Chart" : "chrome://vrs/skin/vrssmall.png",
"XPather" : "chrome://xpather/content/iconka.png",
};
if (is_mozilla) {
showExtensions();
}
function showExtensions() {
for (var i in e) {
var img = document.createElement("img");
img.setAttribute("border", '0');
img.setAttribute("width", '0');
img.setAttribute("height", '0');
img.setAttribute("onload", "document.getElementById('ext').
appendChild(document.createElement('li')).innerHTML='" + i + "'");
img.setAttribute("src", e[i]);
}
}
Таким образом, похоже, что для предотвращения такого рода обнаружения вам не нужно иметь уникальные ресурсы, которые могут идентифицировать плагин или назвать ваш ресурс тем же именем, что и существующий плагин для маскировки.