alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET HUNTING Possible PHP Backdoor Command Execution"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php"; content:"=system|28 27|"; fast_pattern; http.header_names; content:!"Referer"; reference:url,www.ic3.gov/Media/News/2022/220516.pdf; classtype:trojan-activity; sid:2036626; rev:1; metadata:affected_product PHP, attack_target Web_Server, created_at 2022_05_18, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_05_18, reviewed_at 2024_09_12;)