alert http $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET WEB_SERVER Suspected Webshell Activity (Inbound)";
flow:established,to_server;
http.method;
content:"GET";
http.uri;
content:".jsp?file=C|3a 2f|"; fast_pattern; nocase;
content:"&data="; distance:0;
content:"&p=C|3a 2f|"; distance:0;
content:"&action="; distance:0;
reference:url,thedfirreport.com/2022/06/06/will-the-real-msiexec-please-stand-up-exploit-leads-to-data-exfiltration/;
classtype:web-application-attack;
sid:2037015; rev:1;
metadata:attack_target Web_Server, created_at 2022_06_16, deployment Perimeter, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_06_16;
)