On 02/22/2018 04:40 PM, John Hardin wrote:
On Thu, 22 Feb 2018, David Jones wrote:
On 02/22/2018 03:49 PM, John Hardin wrote:
On Thu, 22 Feb 2018, David Jones wrote:
My SA filters just received 45 unsolicited junk emails from Office
365 that hit ENCRYPTED_MESSAGE which subtracted a point. Looking at
72_active.cf, the description for this rule is:
"Message is encrypted, not likely to be spam"
The body of the email was a MIME attachment of
application/pkcs7-mime so SA didn't have access to it for body
content rules.
I am seriously thinking about changing the score on this rule
locally to 1.0 or 2.0 to add points if SA can't do any body checks.
I'd recommend against that. It would be better to do offsetting
scores in a meta rule...
Good idea.
Outlook and Outlook Web was able to display the email
automatically. This may be a new feature that we are about to see
more often to hide spam from SA.
It also hit BAYES_00 (not much can be done to change that),
DCC_CHECK, PYZOR_CHECK, and FSL_BULK_SIG to score 2.88.
...e.g. ENCRYPTED_MESSAGE && (DCC_CHECK || PYZOR_CHECK ||
FSL_BULK_SIG) as bulk encrypted mail seems unlikely
...or possibly ENCRYPTED_MESSAGE && FREEMAIL_FROM
This is not hitting FREEMAIL* rules but I have started treating
anything coming from Google and Office 365 with local meta rules like
this:
header __RCVD_GOOGLE Received =~ /\.google\.com \[/
Is that accurately freemail? Wouldn't that also hit Google corporate
emails?
header __RCVD_OFFICE365 Received =~
/\.outbound\.protection\.outlook\.com \[/
You might want to drop that in your sandbox so that it gets published...
meta __RCVD_FREEMAIL (__RCVD_GOOGLE || __RCVD_OFFICE365)
meta ENA_FREEMAIL (FREEMAIL_FROM || FREEMAIL_REPLYTO ||
FREEMAIL_FORGED_REPLYTO || __RCVD_FREEMAIL)
meta ENA_FREEMAIL_ENCRYPTED_MESSAGE ENCRYPTED_MESSAGE && ENA_FREEMAIL
score ENA_FREEMAIL_ENCRYPTED_MESSAGE 3.0
That above would end up being a net score of +2.0 for freemail sources
of email.
That sounds a lot safer. The rule *was* added with a negative score for
a specific reason, after all...
Sure. The description doesn't sound like a very solid reason to assume
that most encrypted email is ham when we can't do any body checks. :)
Sometimes the passing of time with new spam techniques from software
changes (i.e. Office 365 now auto handling of encrypted email) can allow
this to be abused and need changing. I am just trying to bring this up
in case others may be seeing the same thing in their logs and not
noticed it yet.
I will put it in my sandbox and see how it goes. Thanks
--
David Jones
