false alarms by real secure

[danton () INEXO COM BR (Danton Nunes)]

Real secure traps incoming packets on tcp/25 containing certain strings
that suggest a message being directed to a program (to:|something). It
seems not to distinguish between message headers and message contents and
sounds a false alarm when a message or an attachment to a message contains
something like 'mailbox:/c|/some/funny/place'.

it is possible to launch a DoS attack against firewalls with realsecure
just sending a number of e-mails containing the offending pattern. The
message is not delivered, returning to sendmail w/ I/O error. sendmail
requeues and tries again later, making the alarm ring over and over again.

I don't understand why realsecure mistakes normal e-mail text for an
attack against sendmail (most versions are not vulnerable anyway). Amazingly,
this behaviour is documented as a 'feature'.


--
Danton Nunes      |Informática, Consultoria e Serviços de Acesso à Internet
InterNexo Ltda.   |  http://www.inexo.com.br/  mailto:danton () inexo com br
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