alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Suspected Kapeka/ICYWELL Backdoor Server Response (write to file)"; flow:established,to_client; file_data; content:"|3a 20 22|Write|20|to|20|file|22|,"; fast_pattern; content:"|3a 20 22|C|3a 2f 2f|"; distance:0; reference:url,labs.withsecure.com/content/dam/labs/docs/WithSecure-Research-Kapeka.pdf; reference:url,services.google.com/fh/files/misc/apt44-unearthing-sandworm.pdf; classtype:trojan-activity; sid:2052174; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2024_04_19, deployment Perimeter, deployment SSLDecrypt, malware_family SANDWORM, malware_family APT44, confidence Medium, signature_severity Major, tag RAT, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_19; target:dest_ip;)