Fake User Agents

Hi, is there any way to detect and block (bounce) fake User Agents? By "fake" I mean impossible combinations of browser name/engine/version, OS name/version (e.g. "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 5.1; Trident/3.1)"). Thanks.
5 Replies
CrowdSec
CrowdSec2w ago
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napojihun
napojihun2w ago
you will need to write a scenario for that, take a look on how the - https://app.crowdsec.net/hub/author/crowdsecurity/scenarios/http-bad-user-agent - works and use this as a base for your scenario
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Victor
VictorOP2w ago
Thanks for the reply. Is there any regex list available for matching the fake User Agents (impossible OS - browser version combinations)?
Loz
Loz2w ago
Just cause I know a little but am confused, what makes this UA impossible combination. AFAIK this is primarily used by bots but is not impossible? edit: asked mr gpt, and now I understand why
napojihun
napojihun2w ago
don't think so ( tried to google something ). maybe create a list of the valid user agents and match which are not on the list?

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