Is it possible to filter keywords in a javascript function and comment out the whole function

[msjs08]

Is it possible to filter keywords in a javascript function and comment out the whole function before it gets run?

I've recently been STUNNED by the data that leaks through a browser via javascript, used solely to fingerprint users. I've tried lots of changes in about:config and a few addons but they all fail.

[stephenhawk8054]

Please give example URL and steps to reproduce the issue.

[msjs08]

https://www.deviceinfo.me/
https://amiunique.org/fingerprint
https://browserleaks.com/
Just go there and look at the data these 3 sites can get without you interacting at all. These sites are there to tell you what is being leaked when you go to many websites and you have no idea they are doing it. Blocking javascript disables the site 9/10 the time. I'm thinking a list of common methods that fingerprinting is done with, could stop this in it's tracks.

[stephenhawk8054]

a javascript function

Please give exact javascript function you want to target. Don't tell in general, others won't be able to help investigate if you just give vague descriptions.

[msjs08]

There are hundreds. I just wanted to know if what I was asking is vaguely possible.
As far as I can tell, this is a chunk of javascript that uses window.navigator to pull chunks of data that it should not be getting

if (window.navigator) {
var z = { Find: j.isString(u.find) ? new RegExp(u.find, "i") : u.find, Find2: j.isString(u.find2) ? new RegExp(u.find2, "i") : u.find2, Avoid: u.avoid ? j.isString(u.avoid) ? new RegExp(u.avoid, "i") : u.avoid : 0, Num: u.num ? /\d/ : 0 },
s,
r,
t,
y,
x,
q,
p = navigator.mimeTypes,
w = navigator.plugins;if (u.mimes && p) {
y = j.isArray(u.mimes) ? [].concat(u.mimes) : j.isString(u.mimes) ? [u.mimes] : [];for (s = 0; s < y.length; s++) {
r = 0;try {
if (j.isString(y[s]) && /[^\s]/.test(y[s])) {
r = p[y[s]].enabledPlugin;
}
} catch (v) {}if (r) {
t = this.findNavPlugin_(r, z);if (t.obj) {
A = t.obj;
}if (A && !j.dbug) {
return A;
}
}
}
}if (u.plugins && w) {
x = j.isArray(u.plugins) ? [].concat(u.plugins) : j.isString(u.plugins) ? [u.plugins] : [];for (s = 0; s < x.length; s++) {
r = 0;try {
if (x[s] && j.isString(x[s])) {
r = w[x[s]];
}
} catch (v) {}if (r) {
t = this.findNavPlugin_(r, z);if (t.obj) {
A = t.obj;
}if (A && !j.dbug) {
return A;
}
}
}q = w.length;if (j.isNum(q)) {
for (s = 0; s < q; s++) {
r = 0;try {
r = w[s];
} catch (v) {}if (r) {
t = this.findNavPlugin_(r, z);if (t.obj) {
A = t.obj;
}if (A && !j.dbug) {
return A;
}
}
}
}
}
}return A;
}, findNavPlugin_: function (t, s) {
var r = t.description || "",
q = t.name || "",
p = {};if (s.Find.test(r) && (!s.Find2 || s.Find2.test(q)) && (!s.Num || s.Num.test(RegExp.leftContext + RegExp.rightContext)) || s.Find.test(q) && (!s.Find2 || s.Find2.test(r)) && (!s.Num || s.Num.test(RegExp.leftContext + RegExp.rightContext))) {
if (!s.Avoid || !(s.Avoid.test(r) || s.Avoid.test(q))) {
p.obj = t;
}
}return p;
}, getVersionDelimiter: ",", findPlugin: function (r) {
var q,
p = { status: -3, plugin: 0 };if (!j.isString(r)) {
return p;
}if (r.length == 1) {
this.getVersionDelimiter = r;return p;
}r = r.toLowerCase().replace(/\s/g, "");q = j.Plugins[r];if (!q || !q.getVersion) {
return p;
}p.plugin = q;p.status = 1;return p;
} }, getPluginFileVersion: function (u, q) {
var t,
s,
v,
p,
r = -1;if (!u) {
return q;
}if (u.version) {
t = j.getNum(u.version + "");
}if (!t || !q) {
return q || t || null;
}t = j.formatNum(t);q = j.formatNum(q);s = q.split(j.splitNumRegx);v = t.split(j.splitNumRegx);for (p = 0; p < s.length; p++) {
if (r > -1 && p > r && s[p] != "0") {
return q;
}if (v[p] != s[p]) {
if (r == -1) {
r = p;
}if (s[p] != "0") {
return q;
}
}
}return t;
}, AXO: function () {
var q;try {
q = new window.ActiveXObject();
} catch (p) {}return q ? null : window.ActiveXObject;
}(), getAXO: function (p) {
var r = null;try {
r = new j.AXO(p);
} catch (q) {
j.errObj = q;
}if (r) {
j.browser.ActiveXEnabled = !0;
}return r;
}, browser: { detectPlatform: function () {
var r = this,
q,
p = window.navigator ? navigator.platform || "" : "";j.OS = 100;if (p) {
var s = ["Win", 1, "Mac", 2, "Linux", 3, "FreeBSD", 4, "iPhone", 21.1, "iPod", 21.2, "iPad", 21.3, "Win.*CE", 22.1, "Win.Mobile", 22.2, "Pocket\sPC", 22.3, "", 100];for (q = s.length - 2; q >= 0; q = q - 2) {
if (s[q] && new RegExp(s[q], "i").test(p)) {
j.OS = s[q + 1];break;
}
}
}
}
<\code>

[MasterKia]

So you want to modify some Javascript functions that are used for fingerprinting using uBO scriptlets?
I suggest you use a dedicated extension like Chameleon for that.

[msjs08]

Yes, I was asking if it was possible more than anything. Chameleon spoofs some but still leaks lots.

[stephenhawk8054]

Don't use extensions for preventing fingerprint. They don't have enough scopes to do that and can leak real data. Some browsers have options for those.

---

Back to your question

Is it possible to filter keywords in a javascript function and comment out the whole function before it gets run?

No, you cannot "comment out" part of the script. You can abort some inline scripts or replace parts of the inline scripts, but you need to target exact script to do that and you need to understand how javascript works, there's no general way to do that.

[msjs08]

Bah, I was hoping maybe uBlock could! Thanks for your answer, my other 'idea' is a lot harder.

Creating a proxy with AI identifying the various fingerprinting methods, blocking the scripts entirely and sending random spoofed replies to each method identified. This is way beyond my depth but I know an IT Professor who might like to challenge his students with this.