alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MOBILE_MALWARE XX-Net VPN Client CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/imsi.html?phone="; startswith; fast_pattern; pcre:"/^(?:[0-9]{15})$/R"; http.user_agent; content:"Android"; reference:md5,5faa868d9bbb1f253f9b968ad620604b; classtype:pup-activity; sid:2038903; rev:1; metadata:affected_product Android, attack_target Mobile_Client, created_at 2022_09_19, deployment Perimeter, confidence High, signature_severity Minor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_09_19;)