alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MOBILE_MALWARE iOS/Xsser checking library version"; flow:to_server,established; urilen:18; http.method; content:"GET"; nocase; http.uri; content:"/CheckLibrary.aspx"; http.header_names; content:!"Referer|0d 0a|"; reference:md5,2cba795aff750259a2fc447cdd6ea1c7; reference:url,lacoon.com/lacoon-discovers-xsser-mrat-first-advanced-ios-trojan/; classtype:trojan-activity; sid:2019334; rev:3; metadata:attack_target Mobile_Client, created_at 2014_10_01, signature_severity Major, updated_at 2020_05_12, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)