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Posted to users@spamassassin.apache.org by David Jones <dj...@ena.com> on 2018/01/23 21:52:56 UTC

Pretty good spoof of AmEx

Here is a good example of a spoof that might get user clicks.  It didn't 
have good SPF or DKIM but it could have pretty easily making it look 
pretty clean in a default SA installation.

https://pastebin.com/GTG8K56a

Need to get this IP off of the HostKarma and dnswl.org whitelists if 
anyone from there is on this list.

On the other hand, here is a legit AmEx email that looks nearly 
identical.  I challenge everyone to run these through your SA instances 
by saving them to your servers as a file then running "spamassassin -D < 
file" and see how they score.

https://pastebin.com/KLQyaZrJ

I will be adding this entry to 60_whitelist_auth.cf soon so in less than 
a week the authentic AmEx emails will be scoring very low for everyone 
that is running sa-update regularly:

def_whitelist_auth *@*.aexp.com

Kevin already had something similar to this in KAM.cf checking for 
SPF_FAIL from aexp.com but it wouldn't help with that spoofed one at the 
top with the "m" in the domain.

-- 
David Jones

Re: Pretty good spoof of AmEx

Posted by RW <rw...@googlemail.com>.
On Thu, 25 Jan 2018 01:05:48 +0000
RW wrote:

> On Wed, 24 Jan 2018 03:07:48 -0500
> Rupert Gallagher wrote:
> 
> > To: address matches Reply-To: address.  
> 
> 
> From: Rupert Gallagher <ru...@protonmail.com>
> Reply-To: Rupert Gallagher <ru...@protonmail.com>

Sorry I misread that.

Re: Pretty good spoof of AmEx

Posted by RW <rw...@googlemail.com>.
On Wed, 24 Jan 2018 03:07:48 -0500
Rupert Gallagher wrote:

> To: address matches Reply-To: address.


From: Rupert Gallagher <ru...@protonmail.com>
Reply-To: Rupert Gallagher <ru...@protonmail.com>

Re: Pretty good spoof of AmEx

Posted by Rupert Gallagher <ru...@protonmail.com>.
To: address matches Reply-To: address.

Sent from ProtonMail Mobile

Re: Pretty good spoof of AmEx

Posted by John Hardin <jh...@impsec.org>.
On Tue, 23 Jan 2018, David Jones wrote:

> Here is a good example of a spoof that might get user clicks.  It didn't have 
> good SPF or DKIM but it could have pretty easily making it look pretty clean 
> in a default SA installation.
>
> https://pastebin.com/GTG8K56a

Possible spam sign: multiple instances of "http:///" (three slashes) 
followed by something that does not look even remotely like a FDQN.


-- 
  John Hardin KA7OHZ                    http://www.impsec.org/~jhardin/
  jhardin@impsec.org    FALaholic #11174     pgpk -a jhardin@impsec.org
  key: 0xB8732E79 -- 2D8C 34F4 6411 F507 136C  AF76 D822 E6E6 B873 2E79
-----------------------------------------------------------------------
   [People] are socialists because they are blinded by
   envy and ignorance.       -- economist Ludwig von Mises (1881-1973)
-----------------------------------------------------------------------
  Today: John Moses Browning's 163rd Birthday

Re: Pretty good spoof of AmEx

Posted by Tobi <ja...@gmx.ch>.
Not 100% sure about 168.100.1.4 ip but the 168.100.1.3 ip is used by the official postfix mailinglist. Pretty sure they should not be removed from dnswl :-)


----- Originale Nachricht -----
Von: David Jones <dj...@ena.com>
Gesendet: 24.01.18 - 03:26
An: users@spamassassin.apache.org
Betreff: Re: Pretty good spoof of AmEx

> On 01/23/2018 07:11 PM, Alex wrote:
>> Hi,
>> 
>> On Tue, Jan 23, 2018 at 4:52 PM, David Jones <dj...@ena.com> wrote:
>>> Here is a good example of a spoof that might get user clicks.  It didn't
>>> have good SPF or DKIM but it could have pretty easily making it look pretty
>>> clean in a default SA installation.
>>>
>>> https://pastebin.com/GTG8K56a
>>>
>>> Need to get this IP off of the HostKarma and dnswl.org whitelists if anyone
>>> from there is on this list.
>> 
> 
> Sounds like this is a shared IP with some good senders so this may need 
> to be reported to cloud9.net so they can find the source of this abuse 
> of their server.
> 
>> This appears to have hit on your side. Is this just an FYI?
>> 
> 
> Do you mean my SA (MailScanner) blocked it?  Yes it did.  Mostly due to 
> properly trained Bayes DB, DCC, Pyzor, and a local rules.  Just trying 
> to show my strategy for detecting and blocking spoofing as SPF, DKIM, 
> and DMARC are being properly implemented by companies that are common 
> targets of spoofing.
> 
> Safely whitelist_auth the Envelope-From domain and then setup 
> header/body rules to block the spoofing text.
> 
>> X-ENA-MailScanner-SpamCheck: not spam (whitelisted), SpamAssassin (cached,
>> score=17.85, required 4, BAYES_99 5.20, BAYES_999 0.20,
>> 
>> Yeah, not good.
>> -2.5 RCVD_IN_HOSTKARMA_W    RBL: Sender listed in HOSTKARMA-WHITE
>>                           [168.100.1.4 listed in hostkarma.junkemailfilter.com]
>> -2.3 RCVD_IN_DNSWL_MED      RBL: Sender listed at http://www.dnswl.org/, medium
>>                               trust [168.100.1.4 listed in list.dnswl.org]
>> 
>> Were there no EnvelopeFrom or Return-Path header?
>> 
> 
> EnvelopeFrom domain was welcome.aexp.com as you can see in the 
> Authentication-Results added by my MTA with OpenDMARC.  The legit email 
> has perfect DMARC alignment on both SPF and DKIM and they run with p=reject.
> 
> No Return-Path header in the original.
> 
>> This hits a local rule involving undisclosed-recips and/or not to my
>> domain and "urgent" messages. It also now hits pyzor and dcc
>> 
> 
> Is this Bcc'd recipients?  That can be helpful information but probably 
> not a high scoring rule unless you are combining it in a meta with other 
> hits.
> 
>> I also have a rule that adds 1.2 points to emails that hit hostkarma
>> with no domain security.
>> 
> 
> How is this a sign of spam?  Have you noticed a pattern?  I will search 
> my logs (actually run a SQL query) for this to see if you are onto 
> something here.
> 
>>> Kevin already had something similar to this in KAM.cf checking for SPF_FAIL
>>> from aexp.com but it wouldn't help with that spoofed one at the top with the
>>> "m" in the domain.
>> 
>> Should we try to do something about "american express" with a faked
>> domain (amexp.com)?
>> 
> 
> We could setup a 60_blacklist_from.cf file in the SA ruleset for 
> definite bad domains but that's probably not the best place to maintain 
> that.  It really should be in major DBLs that SA already knows to check.
> 
> -- 
> David Jones


Re: Pretty good spoof of AmEx

Posted by Bill Cole <sa...@billmail.scconsult.com>.
On 23 Jan 2018, at 21:26 (-0500), David Jones wrote:

> We could setup a 60_blacklist_from.cf file in the SA ruleset for 
> definite bad domains but that's probably not the best place to 
> maintain that.  It really should be in major DBLs that SA already 
> knows to check.

+1

Unsurprisingly, running a derogatory reputation service is a toxic 
quagmire that the Apache SpamAssassin Project should not dive into. I 
have nothing but awe and respect for Steve Linford & his team at 
Spamhaus, precisely because they have figured out how to survive while 
publicly saying blatantly unflattering things about many people who have 
little respect for law or basic human decency. Doing that requires human 
and technical infrastructure that I would not expect the ASF or 
independent benefactors to be able or willing to provide. IMHO it is 
risky enough that we essentially bless a subset of a restricted class of 
senders via the "default whitelist" subsystem and we don't need the 
headache of distributing a list of "bad guys" that would need constant 
diligent maintenance to avoid being de facto defamatory. After all, 
domain registrations do expire and people do blindly re-register 
"burner" domains that spammers have had their fill of and let expire.

-- 
Bill Cole
bill@scconsult.com or billcole@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Currently Seeking Steady Work: https://linkedin.com/in/billcole

Re: Pretty good spoof of AmEx

Posted by David Jones <dj...@ena.com>.
On 01/23/2018 07:11 PM, Alex wrote:
> Hi,
> 
> On Tue, Jan 23, 2018 at 4:52 PM, David Jones <dj...@ena.com> wrote:
>> Here is a good example of a spoof that might get user clicks.  It didn't
>> have good SPF or DKIM but it could have pretty easily making it look pretty
>> clean in a default SA installation.
>>
>> https://pastebin.com/GTG8K56a
>>
>> Need to get this IP off of the HostKarma and dnswl.org whitelists if anyone
>> from there is on this list.
> 

Sounds like this is a shared IP with some good senders so this may need 
to be reported to cloud9.net so they can find the source of this abuse 
of their server.

> This appears to have hit on your side. Is this just an FYI?
> 

Do you mean my SA (MailScanner) blocked it?  Yes it did.  Mostly due to 
properly trained Bayes DB, DCC, Pyzor, and a local rules.  Just trying 
to show my strategy for detecting and blocking spoofing as SPF, DKIM, 
and DMARC are being properly implemented by companies that are common 
targets of spoofing.

Safely whitelist_auth the Envelope-From domain and then setup 
header/body rules to block the spoofing text.

> X-ENA-MailScanner-SpamCheck: not spam (whitelisted), SpamAssassin (cached,
> score=17.85, required 4, BAYES_99 5.20, BAYES_999 0.20,
> 
> Yeah, not good.
> -2.5 RCVD_IN_HOSTKARMA_W    RBL: Sender listed in HOSTKARMA-WHITE
>                           [168.100.1.4 listed in hostkarma.junkemailfilter.com]
> -2.3 RCVD_IN_DNSWL_MED      RBL: Sender listed at http://www.dnswl.org/, medium
>                               trust [168.100.1.4 listed in list.dnswl.org]
> 
> Were there no EnvelopeFrom or Return-Path header?
> 

EnvelopeFrom domain was welcome.aexp.com as you can see in the 
Authentication-Results added by my MTA with OpenDMARC.  The legit email 
has perfect DMARC alignment on both SPF and DKIM and they run with p=reject.

No Return-Path header in the original.

> This hits a local rule involving undisclosed-recips and/or not to my
> domain and "urgent" messages. It also now hits pyzor and dcc
> 

Is this Bcc'd recipients?  That can be helpful information but probably 
not a high scoring rule unless you are combining it in a meta with other 
hits.

> I also have a rule that adds 1.2 points to emails that hit hostkarma
> with no domain security.
> 

How is this a sign of spam?  Have you noticed a pattern?  I will search 
my logs (actually run a SQL query) for this to see if you are onto 
something here.

>> Kevin already had something similar to this in KAM.cf checking for SPF_FAIL
>> from aexp.com but it wouldn't help with that spoofed one at the top with the
>> "m" in the domain.
> 
> Should we try to do something about "american express" with a faked
> domain (amexp.com)?
> 

We could setup a 60_blacklist_from.cf file in the SA ruleset for 
definite bad domains but that's probably not the best place to maintain 
that.  It really should be in major DBLs that SA already knows to check.

-- 
David Jones

Re: Pretty good spoof of AmEx

Posted by Alex <my...@gmail.com>.
Hi,

On Tue, Jan 23, 2018 at 4:52 PM, David Jones <dj...@ena.com> wrote:
> Here is a good example of a spoof that might get user clicks.  It didn't
> have good SPF or DKIM but it could have pretty easily making it look pretty
> clean in a default SA installation.
>
> https://pastebin.com/GTG8K56a
>
> Need to get this IP off of the HostKarma and dnswl.org whitelists if anyone
> from there is on this list.

This appears to have hit on your side. Is this just an FYI?

X-ENA-MailScanner-SpamCheck: not spam (whitelisted), SpamAssassin (cached,
score=17.85, required 4, BAYES_99 5.20, BAYES_999 0.20,

Yeah, not good.
-2.5 RCVD_IN_HOSTKARMA_W    RBL: Sender listed in HOSTKARMA-WHITE
                         [168.100.1.4 listed in hostkarma.junkemailfilter.com]
-2.3 RCVD_IN_DNSWL_MED      RBL: Sender listed at http://www.dnswl.org/, medium
                             trust [168.100.1.4 listed in list.dnswl.org]

Were there no EnvelopeFrom or Return-Path header?

This hits a local rule involving undisclosed-recips and/or not to my
domain and "urgent" messages. It also now hits pyzor and dcc

I also have a rule that adds 1.2 points to emails that hit hostkarma
with no domain security.

> Kevin already had something similar to this in KAM.cf checking for SPF_FAIL
> from aexp.com but it wouldn't help with that spoofed one at the top with the
> "m" in the domain.

Should we try to do something about "american express" with a faked
domain (amexp.com)?