alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/rpc"; bsize:4; fast_pattern; http.header_names; content:"|0d 0a|Host|0d 0a|Accept-Encoding|0d 0a|Accept-Language|0d 0a|User-Agent|0d 0a|"; content:!"Referer"; http.accept_lang; content:"en-GB|3b|q=0.9,|20|*|3b|q=0.7"; bsize:20; reference:md5,f7810878118c08539c0cb0c60e4a23b7; reference:md5,8ccc051bbaf6dc9cb76bfea2bbd8f6d4; reference:url,www.cert.ssi.gouv.fr/uploads/CERTFR-2021-CTI-009.pdf; classtype:trojan-activity; sid:2034402; rev:2; metadata:attack_target Client_Endpoint, created_at 2021_11_10, deployment Perimeter, deployment SSLDecrypt, malware_family Cobalt_Strike, performance_impact Significant, confidence Medium, signature_severity Major, tag c2, updated_at 2024_04_04, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)