Cisco PIX Firewall Mailguard Feature SMTP Content Filter Bypass
High Nessus Plugin ID 10520
SynopsisThe remote service is vulnerable to an access control breach.
DescriptionThe remote SMTP server seems to be protected by a content filtering firewall probably Cisco's PIX.
However, an attacker may bypass this content filtering by issuing a DATA command before a MAIL command, that allows him to directly communicate with the real SMTP daemon.