alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Backdoor.Graphon Checkin Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/api/Values_V1/AuthAsyncComplete_V1?Identity="; fast_pattern; startswith; http.uri.raw; content:"=%3E"; http.header_names; content:"|0d 0a|Accept|0d 0a|Host|0d 0a|Connection|0d 0a 0d 0a|"; bsize:30; reference:url,symantec-enterprise-blogs.security.com/blogs/threat-intelligence/harvester-new-apt-attacks-asia; reference:md5,ff81a65150e318c1ffbeaba7a56bb09f; classtype:command-and-control; sid:2034224; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_10_18, deployment Perimeter, deployment SSLDecrypt, malware_family Win32_Backdoor_Graphon, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_10_18;)