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Sensible brute force threshold before alerting?

asked by hgunter 28 days ago

Five failures a minute catches everyone who fat fingers their password. What do people actually use?

2 answers

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aklaha 13 points 28 days ago

Thresholds alone are always either noisy or useless. What helps more is what happens next.

Failures followed by a success from the same source is the alert worth waking somebody for. Failures on their own are background radiation on anything internet facing.

If you want a number, 30 in a minute from one source catches automation without catching humans. Tune per service though, SSH on a public address and an internal app should not share a threshold.

gerald (Gerald) 1 point 15 days ago

Also worth alerting when a single source hits many different usernames, regardless of count. Ten failures against ten accounts is more interesting than a hundred against one.

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