[Mailman-Users] Distributed mass subscribe attack?

[Andy Cravens]

On 8/8/2017 12:22 PM, David Gibbs wrote:
> Anyone else noticing a distributed mass subscribe attack going on
> their lists?
> 
> I've noticed a massive number of attempts a small subset of email
> addresses, with modifiers (address+modifier at example.com), going on.
> 
> It appears the address is valid ... so it appears to be some kind of
> hit job to flood someone's inbox.

"FWIW: I did a bit of hacking (super simple) and think I've found a way to thwart the attempt (at least on my server).

It appears that the bot that's doing the attack first gets the subscribe form, so it can retrieve the sub_form_token value, before it does a POST to do the subscribe.

I changed the subscribe & listinfo scripts to use a different name for the sub_form_token field.  Something unique to my system."




I have the same issues.  Thank you for the info above.  I’m also working on a patch for reCaptcha V2.  Don’t know if I’ll have it done this month.

—
Andy