alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET HUNTING Suspicious csrss.exe in URI"; flow:established,to_server; urilen:<100; http.method; content:"GET"; http.uri; content:"/csrss.exe"; nocase; fast_pattern; endswith; reference:md5,21a069667a6dba38f06765e414e48824; classtype:bad-unknown; sid:2016702; rev:15; metadata:created_at 2013_04_02, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_17;)