A peek into Reddit's anti-spam internals
5 days ago
- #Security
- #Spam Filter
- An unusual bug exposed internal Reddit spam removal reasons to a moderator in 2021.
- Spam removal systems include 'spamurai' (rules-based), 'spammit' (percentage scoring), and shadowbans.
- Domain bans and keyword filters (e.g., 'torenteu') are used to block spam links.
- Reddit uses the Perspective API to detect spam, but this API is being shut down in 2026.
- Spamurai logs extensive data: account age, karma, reports, ISP, user agent, TLS fingerprints, and more.
- URL inspection can follow redirects to detect banned patterns, leading to account bans.
- Anti-spam systems have evolved from CRM114 to REV1, Snooron, and REV2, likely using Lua rules.
- The author withheld details for years to avoid aiding spammers, but now sees the information as less critical due to API deprecation and LLMs.