On Tue, 1 Jan 2008, Timo Sirainen wrote:
On Tue, 2008-01-01 at 15:59 -0500, Dean Brooks wrote:
Hi,
Is there a way, or can a way be added, to add an "auth_failed_delay=10s"
style option that would put in an artificial delay after a failed
password attempt?
As it stands now, Dovecot seems highly vulnerable to widescale
brute-force password dictionary scans.
Even if it's not configurable, can a delay be hardcoded to something
like, say, 10 or 15 seconds?
Failed auth requests are put to a queue that's flushed every 2 seconds.
So there is already a delay. I don't think it's a good idea to increase
it up from 2 seconds, it just gets annoying when you type the wrong
password accidentally.
I'd think the increase in effort required for a dictionary attack would
outweigh the infrequent inconvenience to valid users.
Although I suppose I could change the code so that it always waits 2
seconds instead of flushing all of them.
Any reason that '2 seconds' couldn't be configurable (with a default of
2)? In my situation, I'm the only user of my system, and I use reasonably
secure passwords, so brute-force doesn't really scare me. As a sysadmin at
an ISP or company with (too-)lenient password requirements, on the other
hand, it'd be nice to slow an attack by a larger factor.
Best,
Ben
