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Episode #815 Quiz

Homogeneity Attacks
Date: 2021-04-20 | Length: 1.75 hrs | Episode page at twit.tv

About this episode

Google’s FLoC groups browser histories into k-anonymous cohorts for ad targeting after third-party cookies vanish. Chrome 90 also defaults to HTTPS, blocks port 554 to reduce NAT slipstreaming risk, adds AV1 for WebRTC, and supports text-fragment URLs. Chrome’s implementation mitigates homogeneity attacks with t-closeness, suppressing cohorts linked to sensitive categories.

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Question 1: According to the episode, what specific browser-side property of Google’s FLoC implementation is intended to stop homogeneity attacks from exposing a sensitive attribute through a cohort ID?

Question 1

According to the episode, what specific browser-side property of Google’s FLoC implementation is intended to stop homogeneity attacks from exposing a sensitive attribute through a cohort ID?

It encrypts cohort IDs so only Google can decode them It ensures cohorts satisfy k-anonymity and t-closeness It replaces cohort IDs with rotating per-site random tokens It limits cohort membership to users who visited only one site category

Question 2: What example did Google use to illustrate a homogeneity attack in the FLoC paper?

Question 2

What example did Google use to illustrate a homogeneity attack in the FLoC paper?

A cohort made up only of users visiting a rare medical-condition site A cohort made up only of users visiting a password manager site A cohort made up only of users visiting a political campaign site A cohort made up only of users visiting a banking login page

Question 3: What lifetime does the episode say FLoC uses for the browsing history that informs a user’s cohort ID?

Question 3

What lifetime does the episode say FLoC uses for the browsing history that informs a user’s cohort ID?

A fixed thirty-day window A fixed seven-day window An indefinite lifetime until the browser is reset A rolling one-day window

Question 4: Which categories does the episode say Google already forbids for interest-based advertising and uses as the basis for defining sensitive content in the FLoC paper?

Question 4

Which categories does the episode say Google already forbids for interest-based advertising and uses as the basis for defining sensitive content in the FLoC paper?

Gaming, finance, travel, and shopping sites News, sports, education, and entertainment sites Cloud, development, security, and productivity sites Adult, medical, political, and religious sites

Question 5: What did the episode say the FBI’s court-authorized Exchange operation did, and what did it explicitly not do?

Question 5

What did the episode say the FBI’s court-authorized Exchange operation did, and what did it explicitly not do?

It quarantined infected servers and reset all administrator passwords It patched vulnerabilities but left web shells in place for owners to remove It removed web shells and patched Exchange vulnerabilities It copied and removed web shells but did not patch vulnerabilities or search for other malware

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