alert tcp $EXTERNAL_NET any -> $HOME_NET 53 (msg:"GPL DNS named overflow attempt"; flow:to_server,established; content:"|CD 80 E8 D7 FF FF FF|/bin/sh"; reference:url,www.cert.org/advisories/CA-1998-05.html; classtype:attempted-admin; sid:2100261; rev:7; metadata:created_at 2010_09_23, confidence Medium, signature_severity Informational, updated_at 2019_07_26;)