Show HN: Detecting adblock, without JavaScript, by abusing HTTP 103 responses

Original Article ↗ Hacker News Discussion ↗

Technique: Detecting Adblock via HTTP 103 Early Hints

  • Commenters find the HTTP 103 mechanism technically clever and learn about Early Hints for the first time.
  • Key insight: resources hinted before the main HTML let servers infer whether a browser/adblocker fetched them, then tailor subsequent HTML.
  • Some note similar tricks are possible with Link HTTP headers or by partially streaming the HTML and pausing to observe subresource loading, without JavaScript.

Feasibility, Reliability, and Browser Behavior

  • Skeptics argue this is likely too brittle for large-scale use:
    • Corporate proxies and older stacks may mishandle 103 responses.
    • Many sites don’t stream HTML or are horizontally scaled, making the required stateful coordination expensive.
  • Others note Chrome’s design (always loading Early Hints, hiding them from extensions) makes this mostly a Firefox-specific issue today.
  • A mitigation suggestion: browsers could always load Early Hints but discard or delay them, or block 103 entirely, though that may hurt performance.

Arms Race: Adblockers, DRM, and Anti-User Features

  • Several foresee continued escalation:
    • Stronger anti-adblock measures, possibly using DRM-style techniques (e.g., Widevine-like protection for web pages, Web Environment Integrity proposals).
    • Countermeasures like browser/OS-level or even HDMI-level ad removal overlays.
  • Some note current adblockers can’t easily block DRM-embedded ads; others counter that DRM has been and can be subverted, though hardware-level protections complicate this.

User Experience, Ethics, and Economics of Ads

  • Many users say they block ads primarily due to annoyance, intrusiveness, tracking, and malware risk, not bandwidth savings.
  • Some argue sabotaging adblocking is unethical and should even be illegal; others insist sites have the right to refuse service to adblock users.
  • There’s debate whether forcing ads drives users away or is necessary for sustainability; evidence is seen as unclear.
  • Alternatives discussed:
    • Pay-with-compute (e.g., controlled cryptomining) is attractive to some but criticized as bad for battery devices and likely far less lucrative than targeted ads.
    • Paid, ad-free models exist but are often expensive, still include ads or tracking, or are impractical for infrequently visited sites.

Security/Disclosure and Meta Points

  • Some think this technique should have been privately reported to browser and adblock developers first; others frame it as a typical “white-hat vs black-hat” disclosure dilemma.
  • Multiple comments emphasize that users, publishers, advertisers, and platforms all share responsibility for today’s hostile ad ecosystem.