drop tcp $EXTERNAL_NET any -> $HOME_NET $SMTP_PORT (msg:"[SENDMAIL] EXPN command - [not rejected]"; content:"expn "; content:!"rejected"; nocase; fwsam: src, 1 day; classtype: attempted-recon; flowbits: set, recon, 86400; program: sm-mta|sendmail; reference: url,wiki.quadrantsec.com/bin/view/Main/5000035; parse_src_ip: 1; reference:arachnids,31; reference:cve,1999-0531; reference:nessus,10249; sid: 5000223; rev:8;)

-- Main.Sagan-Wiki-Add - 2015-10-21

New revisions of 5000223 will be below...

drop any $EXTERNAL_NET any -> $HOME_NET any (msg:"[SENDMAIL] EXPN command - [not rejected]"; content:"expn "; content:!"rejected"; nocase; default_proto: tcp; default_dst_port: $SMTP_PORT; classtype: attempted-recon; xbits: set,recon,track ip_src, expire 86400; program: sm-mta|sendmail; reference: url,wiki.quadrantsec.com/bin/view/Main/5000035; parse_src_ip: 1; reference:arachnids,31; reference:cve,1999-0531; reference:nessus,10249; sid: 5000223; rev:11;)

-- Main.Sagan-Wiki-Add - 2021-4-12