alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Bitter APT Backdoor Related Activity"; flow:established,to_server; dsize:3; content:"|03 00 dc|"; fast_pattern; threshold:type both, count 2, seconds 5, track by_src; reference:md5,bd054c4f43808ef37352f36129bf0c3d; reference:md5,06a7eccd74a6aa5aa12755cd48829f90; reference:md5,532345089619a1881176588a587d3cf1; reference:url,ShadowChasing1/status/1504833720489951234; classtype:trojan-activity; sid:2035533; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_03_18, deployment Perimeter, malware_family Bitter, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_03_18;)