@sarahjamielewis@mastodon.social
Post #4213022
2026-07-29 20:48 UTC
TIL Deep within the firefox source tree, there is a binary file called adult_set.bin, it's a set of md5 hashes for "adult sites"
https://searchfox.org/firefox-main/source/third_party/application-services/components/filter_adult/src/adult_set.bin
Most of these were previously stored in the firefox source code as base64'd hashes, and have been reverse engineered (https://gist.github.com/roycewilliams/04ed6eb9509b83ce4d85873861c7f7b4) (thanks for documenting that @tychotithonus@infosec.exchange)
As far as I can tell, there is a single new entry in the list :
df26afcce27598ce38a4e4852cbb3380 (whose domain is documented here https://phabricator.services.mozilla.com/D15915)
Replies (2)
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@sarahjamielewis@mastodon.social 2026-07-29 21:02
Do I love the existence of an barely documented binary blob in an open source browser project attached to "filtering" functionality? No, I can't say I do. According to contemporary reports and discussion, this filtering functionality was first added so that such sites were not displayed next to "commercial partners". So that's fun.
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@tychotithonus@infosec.exchange 2026-07-29 21:35
@sarahjamielewis@mastodon.social Hey, cool! Note that we couldn't reverse anything here - had to use classic cracking, trying lots of host/domain combos until we got exact hits. Kudos to @s3inlc@infosec.exchange for getting some really hard ones at the end!