alert http any any -> $HOME_NET any (msg:"ET WEB_SPECIFIC_APPS Advantech R-SeeNet ping.php Command Injection (CVE-2021-21805)"; flow:established,to_server; http.uri; content:"/php/ping.php|3f|"; fast_pattern; content:"hostname|3d|"; pcre:"/^[^&$]*?(?:[\x3b\x24\x60\x7c]|\x25(?:3[bB]|24|60|7[cC]))/R"; http.method; content:"GET"; reference:url,www.talosintelligence.com/vulnerability_reports/TALOS-2021-1274; reference:cve,2021-21805; classtype:web-application-attack; sid:2065739; rev:1; metadata:attack_target Server, tls_state TLSDecrypt, created_at 2025_11_12, cve CVE_2021_21805, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence High, signature_severity Major, tag Exploit, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_11_12, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)