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| privacy:requests [2026/08/29 12:44] – Repoint three figures the carve-out left behind (EasyList Cookie List rule counts, the version/engine examples in What to Report, the MV3 rule-count comparison) at Programming:Filter Lists, where they are maintained, instead of holding stale copies that d karel.kubicek.claude | privacy:requests [2026/09/16 10:59] (current) – Add one-line disambiguator: this page is HTTP requests, privacy:data_subject_rights is DSARs. Authored by Claude karel.kubicek.claude |
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| ====== Classifying Web Requests ====== | ====== Classifying Web Requests ====== |
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| | //**HTTP** requests — the ones a browser sends to a server. For access, deletion and opt-out requests sent by a person to a company, see [[Privacy:Data subject rights]].// |
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| A common task in web privacy measurements is to determine which web requests correspond to the benign loading of required web resources and which are used to track users. There are two main methods for such classification: matching requests against crowd-sourced lists (typically used in ad-blocking or tracking protection extensions) or using machine learning (**ML**) to classify the requests based on their context and request URL. | A common task in web privacy measurements is to determine which web requests correspond to the benign loading of required web resources and which are used to track users. There are two main methods for such classification: matching requests against crowd-sourced lists (typically used in ad-blocking or tracking protection extensions) or using machine learning (**ML**) to classify the requests based on their context and request URL. |
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| * **A rule is evaluated against a request //in context//.** ''$third-party'', ''$domain='', the resource-type options and ''@@'' exception rules all need the initiator URL, the resource type and the redirect chain. A crawl that logged only request URLs cannot be post-processed with a list, and it fails silently rather than erroring. | * **A rule is evaluated against a request //in context//.** ''$third-party'', ''$domain='', the resource-type options and ''@@'' exception rules all need the initiator URL, the resource type and the redirect chain. A crawl that logged only request URLs cannot be post-processed with a list, and it fails silently rather than erroring. |
| * **The list is a moving target.** EasyList publishes a ''Version:'' and a ''Commit:'' in its own header and changes several times an hour; of the 178 corpus papers naming a list as a tool, **four** record something that identifies the rules they matched against. | * **The list is a moving target.** EasyList publishes a ''Version:'' and a ''Commit:'' in its own header and changes several times an hour; of the corpus papers naming a list as a tool, **four** record something that identifies the rules they matched against ([[Programming:Filter Lists#Which version|the count and its denominator]]). |
| * **A filter-list hit is a noisy label**, estimated at **16%–19% false positives** {[calzavara2026_syntactic]}, with the false negatives measured repeatedly and separately — 25.22% {[fouad2020_missed]}, 34.5% {[lee2023_track]}, and much worse off the desktop web. | * **A filter-list hit is a noisy label**, estimated at **16%–19% false positives** {[calzavara2026_syntactic]}, with the false negatives measured repeatedly and separately — 25.22% {[fouad2020_missed]}, 34.5% {[lee2023_track]}, and much worse off the desktop web. |
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| | Khandelwal et al. {[khandelwal2023automated]}, USENIX Sec 2023 (CookieEnforcer) | Candidate-element extraction, then **BERT** | **T5-Large** predicting the click sequence | 986 of 2,000 domains, 2 false positives and 16 false negatives; **93.7% end-to-end** on 1,000 sites. At scale: notices on **52.7%** of 85,473 sites, 35.4% of them multi-view, and only **21.5%** offering a one-click opt-out | | | Khandelwal et al. {[khandelwal2023automated]}, USENIX Sec 2023 (CookieEnforcer) | Candidate-element extraction, then **BERT** | **T5-Large** predicting the click sequence | 986 of 2,000 domains, 2 false positives and 16 false negatives; **93.7% end-to-end** on 1,000 sites. At scale: notices on **52.7%** of 85,473 sites, 35.4% of them multi-view, and only **21.5%** offering a one-click opt-out | |
| | Ogut et al. {[ogut2024_dissecting]}, USENIX Sec 2024 | XPath plus privacy-word pools, validated by hand | — | Notices on 37% of loaded sites; the paper to read on **language**, since button text is the classifier's input | | | Ogut et al. {[ogut2024_dissecting]}, USENIX Sec 2024 | XPath plus privacy-word pools, validated by hand | — | Notices on 37% of loaded sites; the paper to read on **language**, since button text is the classifier's input | |
| | Bouhoula et al. {[bouhoula2024automated]}, USENIX Sec 2024 | EasyList Cookie List plus custom heuristics | **BERT** on 2353 hand-annotated interactive-element texts, six labels | **100.0% precision and 86.9% recall** on notice detection; the six-label element classifier reached **95.1% accuracy and F1 90.9%** in 5-fold cross-validation, with double annotation agreeing at **Cohen's κ = 91%** | | | Bouhoula et al. {[bouhoula2024_automated]}, USENIX Sec 2024 | EasyList Cookie List plus custom heuristics | **BERT** on 2353 hand-annotated interactive-element texts, six labels | **100.0% precision and 86.9% recall** on notice detection; the six-label element classifier reached **95.1% accuracy and F1 90.9%** in 5-fold cross-validation, with double annotation agreeing at **Cohen's κ = 91%** | |
| | Demir et al. {[demir2024_bannertools]}, PETS 2024 | Compared existing banner-interaction extensions | — | Each extension interacts with **12 banners on average, 65%** of those shown (SD 21%, min 48%, max 95%) — the number to cite when you justify not using an off-the-shelf extension | | | Demir et al. {[demir2024_bannertools]}, PETS 2024 | Compared existing banner-interaction extensions | — | Each extension interacts with **12 banners on average, 65%** of those shown (SD 21%, min 48%, max 95%) — the number to cite when you justify not using an off-the-shelf extension | |
| | Tang et al. {[tang2025_navigating]}, USENIX Sec 2025 //(a compliance result, listed for its detector)// | Random forest on home pages, 1,000 hand-annotated | — | Global comparison; **96.18% (EU) to 97.72% (US)** of sites had at least one consent violation, and only 3.82% enforced preferences correctly | | | Tang et al. {[tang2025_navigating]}, USENIX Sec 2025 //(a compliance result, listed for its detector)// | Random forest on home pages, 1,000 hand-annotated | — | Global comparison; **96.18% (EU) to 97.72% (US)** of sites had at least one consent violation, and only 3.82% enforced preferences correctly | |
| | held-out test set | 5 | 2.9% | | | held-out test set | 5 | 2.9% | |
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| **One paper in three reports no validation of its request classification at all.** The ''not-applicable'' row is mostly papers that applied a list as-is and reasonably consider the list itself the definition — **45 of those 58 papers** carry that ''not-applicable'' verdict on a ''blocklist'' tuple — which is exactly the assumption Calzavara et al. {[calzavara2026_syntactic]} measured at 16%–19% false positives. Manual validation of a sample is an afternoon's work and it is the single cheapest thing you can add. | **One paper in three reports no validation of its request classification at all** — against a 70.1% rate across all 4,439 papers that classify anything ([[Statistics:Annotation]], which owns the corpus-wide figures and what each validation kind is worth). The ''not-applicable'' row is mostly papers that applied a list as-is and reasonably consider the list itself the definition — **45 of those 58 papers** carry that ''not-applicable'' verdict on a ''blocklist'' tuple — which is exactly the assumption Calzavara et al. {[calzavara2026_syntactic]} measured at 16%–19% false positives. Manual validation of a sample is an afternoon's work and it is the single cheapest thing you can add. |
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| ==== Almost nobody says which version of the list ==== | ==== Almost nobody says which version of the list ==== |
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| * [[Programming:Crawler|Comparison of crawling libraries]] — what records the initiator chain, the call stack and the response headers these methods need. | * [[Programming:Crawler|Comparison of crawling libraries]] — what records the initiator chain, the call stack and the response headers these methods need. |
| | * [[Privacy:Browser protection|Measuring with browser tracking protections on]] — this page assumes the default browser. If your crawl ran Firefox, Brave, Safari or Edge, part of what you were trying to classify was blocked before you saw it, and the protection is a treatment you can vary on purpose. |
| * [[Programming:Crawler:Tracker Radar Collector|Tracker Radar Collector]] — the lowest-effort crawler for this task, and where the Tracker Radar data comes from. | * [[Programming:Crawler:Tracker Radar Collector|Tracker Radar Collector]] — the lowest-effort crawler for this task, and where the Tracker Radar data comes from. |
| * [[Programming:Crawler:PageGraph|Brave PageGraph]] — AdGraph's production successor, and the practical way to get a page-execution graph. | * [[Programming:Crawler:PageGraph|Brave PageGraph]] — AdGraph's production successor, and the practical way to get a page-execution graph. |
| * [[Programming:Crawler:webXray|webXray and domain-to-company ownership]] — once a request is flagged, this is how to answer //whose// it is, and why webXray, Tracker Radar and Disconnect give three different answers. | * [[Design:Ownership resolution]] — once a request is flagged, this is how to answer //whose// it is, and why webXray, Tracker Radar and Disconnect give three different answers. (It was under [[Programming:Crawler:webXray]] until 2026-09-11.) |
| * [[Privacy:JavaScript|Analysing and classifying JavaScript]] — the script-level and function-level end of the granularity ladder. | * [[Privacy:JavaScript|Analysing and classifying JavaScript]] — the script-level and function-level end of the granularity ladder. |
| * [[Privacy:Cookies|Cookies]] and [[Privacy:Fingerprinting|Fingerprinting]] — the other two things a "tracking" label is often about. | * [[Privacy:Cookies|Cookies]] and [[Privacy:Fingerprinting|Fingerprinting]] — the other two things a "tracking" label is often about. |
| * [[Privacy:Consent|Granting consent to websites]] — what the cookie notice means, once you have found it. | * [[Privacy:Consent|Granting consent to websites]] — what the cookie notice means, once you have found it. |
| * [[Design:Website Classification|Website classification]] — and the measured reason **not** to use a categorisation service to find trackers. | * [[Design:Website Classification|Website classification]] — and the measured reason **not** to use a categorisation service to find trackers. |
| | * [[Design:Connected TV]] — where the instruments on this page stop working: no request interception without network-level capture, no page context to attribute a request to, and filter lists with a measured coverage of 22–27%. |
| | * [[Statistics:Annotation|Annotation and Validation]] — validating a label set whatever it labels, and why a held-out set drawn from one crawl is usually not held out. |
| * [[Programming:Stateful Stateless|Stateful vs stateless crawling]] and [[Programming:Interaction|Interaction]]. | * [[Programming:Stateful Stateless|Stateful vs stateless crawling]] and [[Programming:Interaction|Interaction]]. |
| * [[provenance:privacy:requests|Provenance of this page's figures]]. | * [[provenance:privacy:requests|Provenance of this page's figures]]. |
