Interesting insight that, in most cases I'd think B and C are likely to be
on the same network, possibly protected by the same spam filtering, meaning
that A's email wouldn't reach B. I know this isn't always the case, just my
thoughts on it.

The above would help reduce the probability of finding a scenario where this
would work, that said securing against social engineering attacks is a tad
challenging :)

Again all of the above just my two cents.

Kind regards.

Hamlesh Motah.
IT Consultant.

tel: +44 (0)709 212 0732
fax: +44 (0)709 212 0732
ema: admin (at) hamlesh (dot) com [email concealed]
web: www.hamlesh.com

Hamlesh Consultants - IT Consultancy - Total Solutions Provider.

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: -----Original Message-----
: From: R Armiento [mailto:rar_bt (at) armiento (dot) se [email concealed]]
: Sent: 16 June 2004 11:26
: To: bugtraq (at) securityfocus (dot) com [email concealed]
: Subject: Is predictable spam filtering a vulnerability?
:
:
:
: During a recent email conversation with several participants,
: we discovered that the email service of one participant
: silently dropped legitimate emails that happened to contain
: certain combinations of words common in spam. I believe this
: sort of filter is common practice, and in fact even in place
: for some of my own email addresses.
:
: However, this experience made me think: isn't predictable
: spam filtering in general a vulnerability that could be used
: as a hoax device? Since most users reply to an email citing
: the complete source email, including filter-offending words,
: it should be possible to keep a reply, forward, or even a
: whole thread, under the radar of specific recipients. If used
: in combination with forged replies from addresses predictably
: dropping emails, I think this may be a dangerous tool for
: social engineering.
:
: For example: attacker 'A' sends 'B' a social engineering
: request for "the secret plans" and says "if you are unsure,
: forward my request to your boss and ask if this is okay". 'B'
: forwards the email to his boss 'C' and asks "Is this okay?".
: However, 'C':s spam filter silently drops the email. 'A'
: forges a reply from 'C' saying: "Sure, no problem, go ahead."
:
: Regards,
: R. Armiento
:

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