alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET HUNTING Suspicious Windows Installer UA for non-MSI"; flow:established,to_server; http.method; content:"GET"; http.uri; content:!".msi"; endswith; http.user_agent; content:"Windows Installer"; depth:17; endswith; fast_pattern; http.header_names; content:!"Referer"; reference:md5,8000f557f5e8e256b6bd66c82e02aced; classtype:policy-violation; sid:2038809; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_09_14, deployment Perimeter, performance_impact Moderate, confidence Medium, signature_severity Major, updated_at 2022_09_13;)