alert udp $EXTERNAL_NET any -> $HOME_NET 69 (msg:"ET EXPLOIT TFTP Invalid Mode in file Get"; content:"|01|"; depth:1; content:"|00|"; distance:1; content:"|00|"; distance:0; content:!"|00|binary|00|"; nocase; content:!"|00|netascii|00|"; nocase; content:!"|00|mail|00|"; nocase; classtype:non-standard-protocol; sid:2003198; rev:4; metadata:created_at 2010_07_30, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)