http://issues.apache.org/SpamAssassin/show_bug.cgi?id=5644





------- Additional Comments From [EMAIL PROTECTED]  2007-11-13 00:53 -------
(In reply to comment #4)
> On a general note: I'm observing occasional similar degenarete cases
> (as are also reported on a mailing list from time to time) ever since
> the change was made from one-line-at-a-time rule application, to
> per-paragraph rule application. Such cases are not frequent, but when
> they hit, it is not unusual they cause a massive disruption in mail flow,
> mostly because such mail comes in multiple similar instances at about
> the same period. Admittedly it is often the mainstream SARE rules that
> take the worst hit, but the problem is not exclusive to SARE rules.
> 
> When SpamAssassin takes more then a period a client is willing
> to wait (depending on a setup), a timed-out mail may stay in a
> MTA queue for a retry, aggreviating the situation.
> 
> The situation is quite unfortunate. If someone should want to cause
> a DoS, it should not be too hard to target a couple of problematic
> rules and devise a crafted message to purposely cause lengthy regexp
> evaluation. I wonder if this is a good situation for a reputation of
> a service that more and more folks depend upon to run mostly unattended.
> 
> Apart from reverting to per-line regexps (at the expense of accuracy),
> I don't have a good solution. Perhaps limiting paragraphs in size,
> maybe compressing spans of 3+ occurrences of same characters before
> applying rules, ... ?

I think we should discuss reverting back to per-line regexps, as
I agree with your thoughts regarding reliability etc. 

Shall I open a bug?



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