From 5da28b0f8771834ae208d61431d632875e9f8e7d Mon Sep 17 00:00:00 2001 From: Ruben Rodriguez Date: Thu, 8 Sep 2022 20:18:54 -0400 Subject: Updated extensions: * Upgraded Privacy Redirect to 1.1.49 and configured to use the 10 most reliable invidious instances * Removed ViewTube * Added torproxy@icecat.gnu based on 'Proxy toggle' extension * Added jShelter 0.11.1 * Upgraded LibreJS to 7.21.0 * Upgraded HTTPS Everywhere to 2021.7.13 * Upgraded SubmitMe to 1.9 --- .../jsr@javascriptrestrictor/wrappingS-SENSOR.js | 136 +++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 data/extensions/jsr@javascriptrestrictor/wrappingS-SENSOR.js (limited to 'data/extensions/jsr@javascriptrestrictor/wrappingS-SENSOR.js') diff --git a/data/extensions/jsr@javascriptrestrictor/wrappingS-SENSOR.js b/data/extensions/jsr@javascriptrestrictor/wrappingS-SENSOR.js new file mode 100644 index 0000000..a61b617 --- /dev/null +++ b/data/extensions/jsr@javascriptrestrictor/wrappingS-SENSOR.js @@ -0,0 +1,136 @@ +/** \file + * \brief Wrappers for Generic Sensor API + * + * \see https://www.w3.org/TR/generic-sensor/ + * + * \author Copyright (C) 2021 Radek Hranicky + * + * \license SPDX-License-Identifier: GPL-3.0-or-later + */ +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see . +// + +/** \file + * \ingroup wrappers + * + * MOTIVATION + * The risk of using Generic Sensor API calls for device fingerprinting is + * mentioned within the W3C Candidate Recommendation Draft, 29 July 2021 + * (https://www.w3.org/TR/2021/CRD-generic-sensor-20210729/#device-fingerprinting) + * Documented threats include manufacturing imperfections and differences + * that are unique to the concrete model of the device and can be used + * for fingerprinting. + * + * We discovered another loophole in the `Sensor.timestamp` attribute. The value + * describes when the last `Sensor.onreading` event occurred, in millisecond precision. + * We observed the time origin is not the time of browsing context creation + * but the last boot time of the device. Exposing such information is dangerous + * as it allows to fingerprint the user easily. It is unlikely that two different + * devices will boot at exactly the same time. + * + * Tested with the Magnetometer sensor on the following devices: + * - Samsung Galaxy S21 Ultra; Android 11, kernel 5.4.6-215566388-abG99BXXU3AUE1, Build/RP1A.200720.012.G998BXXU3AUE1 + * Chrome 94.0.4606.71 and Kiwi (Chromium) 94.0.4606.56 + * - Xiaomi Redmi Note 5; Android 9, kernel 4.4.156-perf+, Build/9 PKQ1.180901.001 + * Chrome 94.0.4606.71 + * + * + * WRAPPING + * + * The wrapper thus protects device by changing the time origin to the browsing context + * creation time, whereas the timestamp should still uniquely identify the reading. + * This is achieved in the following way: + * - At the first reading, we calculate the difference between the original value + * and performance.now(). This gives us the offset between 1) the device boot + * and 2) the page context initialization. + * - On every reading, the offset is subtracted from the original value. The resulting + * value then uniquely identifies the reading sample without exposing the boot time. + * - Like in the other time precision wrappers, the resulting timestamp is processed + * by the mitigation function before return. The mitigation may round and (optionally) + * add noise to the resulting timestamp. + * + * + * POSSIBLE IMPROVEMENTS + * in protection level 2, the timestamp origin may be set to a random value based + * on the session hash. This can serve as a "fake boot time." + */ + + /* + * Create private namespace + */ + (function() { + + var remember_past_values = `var precision = args[0]; + var doNoise = args[1]; + var pastValues = {}; + ${rounding_function} + ${noise_function} + var mitigationF = rounding_function; + if (doNoise === true){ + mitigationF = function(value, precision) { + let params = [value, precision]; + if (params in pastValues) { + return pastValues[params]; + } + let result = noise_function(...params); + pastValues[params] = result; + return result; + } + } + var offsetCompStartPageStart = undefined; + `; + + var wrappers = [ + { + /** + * \see https://dom.spec.whatwg.org/#ref-for-dom-event-timestamp%E2%91%A0 + */ + parent_object: "Sensor.prototype", + parent_object_property: "timestamp", + wrapped_objects: [], + helping_code: remember_past_values + `let origGet = Object.getOwnPropertyDescriptor(Sensor.prototype, "timestamp").get`, + post_wrapping_code: [ + { + code_type: "object_properties", + parent_object: "Sensor.prototype", + parent_object_property: "timestamp", + wrapped_objects: [], + /** \brief replaces Sensor.prototype.timestamp getter to create + * a timestamp with the desired precision. + */ + wrapped_properties: [ + { + property_name: "get", + property_value: ` + function() { + orig_val = origGet.call(this); + if (typeof orig_val != 'number') { + // Sensor is not available or there is no reading yet. + return orig_val; + } + if (offsetCompStartPageStart === undefined) { + // The offset has not been set yet so it needs to be calculated. + offsetCompStartPageStart = orig_val - performance.now(); + } + return mitigationF(orig_val - offsetCompStartPageStart, precision); + }`, + }, + ], + } + ], + }, + ] + add_wrappers(wrappers); + })() -- cgit v1.2.3