For the record,it's all of the Azure, Google, AWS Cloud, Tencent and
many other cloud providers that are now abused for BEC Email Compromise,
and dictionary attacks.
Since very few 'servers' are used for email authentication/clients it is
quite effective to block email auth from those providers by default.
MagicMail servers allow blocking AUTH from those ranges by default,
except for allowed exemptions, for the last couple years as it has got
that bad.
There is a difference between an email client, and other devices, so
various fingerprinting and identification tricks in the SMTP and IMAP
servers can help.
But there are edge cases to consider, eg desktop in the cloud, and IMAP
monitoring SaaS tools, but in general.. blocking AUTH from cloud
providers that don't quickly respond to abuse complaints, is the way to
go ;0
Happy New Year All..
On 1/1/24 02:05, Marco Moock via mailop wrote:
Am 01.01.2024 um 01:46:44 Uhr schrieb Randolf Richardson, Postmaster
via mailop:
Is anyone seeing large numbers of dictionary attacks from
20.42.100.251 (which is owned by Microsoft)? I'm curious if they're
engaging in large-scale targeting.
Doesn't have a PTR, so no regular mail server.
I assume it is one of their Azure customers servers that has been
hacked or is rented by an abuser.
P.S.: I don't bother reporting abuse directly to Microsoft anymore
because in the past they just bounced every message sent to their
postmaster@ and abuse@ accounts.
For what reason did the bounce those messages?
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