alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT Related CR4T Dropper Activity M2 (GET)"; flow:established,to_server; urilen:<20; http.method; content:"GET"; http.uri; content:"/inst"; startswith; fast_pattern; content:".xml"; endswith; http.user_agent; pcre:"/^[A-Za-z]{23}$/"; http.header_names; content:"|0d 0a|User-Agent|0d 0a|Host|0d 0a|Cache-Control|0d 0a 0d 0a|"; bsize:37; reference:md5,48c8e8cc189eef04a55ecb021f9e6111; reference:md5,9d20cc7a02121b515fd8f16b576624ef; reference:url,securelist.com/dunequixote/112425/; classtype:trojan-activity; sid:2052241; 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_23, deployment Perimeter, deployment SSLDecrypt, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_23; target:src_ip;)