alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Suspected CHAOS CnC Inbound (keylogger start)"; flow:established,to_client; dsize:21; content:"a2V5bG9nZ2VyX3N0YXJ0|0a|"; reference:url,github.com/tiagorlampert/CHAOS; classtype:command-and-control; sid:2029798; rev:1; metadata:attack_target Client_Endpoint, created_at 2020_04_02, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_02;)