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Block external font-face set #49

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merged 1 commit into from
Sep 11, 2024
Merged

Block external font-face set #49

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6 changes: 4 additions & 2 deletions packages/core/src/element.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,10 @@ function creator(style, tag, text = '') {

const invoker = creator => () => creator();

// an element that is hard to find/select
export const unselectable = invoker(creator({
// an element that it should be hard to find/select/leak from/etc
export const hardened = invoker(creator({
// decide on an unguessable font-family (non-existing) so an external one cannot be applied
'font-family': rand(20),
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Why not go even higher than 20?

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What number would be sufficient?

// makes element uneditable to prevent document.execCommand HTML injection attacks
'-webkit-user-modify': 'unset',
// makes element unselectable to prevent getSelection attacks
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6 changes: 3 additions & 3 deletions packages/core/src/lavadome.mjs
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Expand Up @@ -10,7 +10,7 @@ import {
replaceChildren,
textContentSet,
} from './native.mjs';
import {distraction, unselectable} from './element.mjs';
import {distraction, hardened} from './element.mjs';
import {getShadow} from './shadow.mjs';

export function LavaDome(host, opts) {
Expand All @@ -23,8 +23,8 @@ export function LavaDome(host, opts) {
const shadow = getShadow(host, opts);
replaceChildren(shadow);

// child of the shadow, where the secret is set, must be unselectable
const child = unselectable();
// child of the shadow, where the secret is set, must be hardened
const child = hardened();
appendChild(shadow, child);

function text(text) {
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