alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET WEB_CLIENT pshell dl/execute primitives in wideb64 4"; flow:established,to_client; file_data; content:"U3RhcnQtUHJvY2Vzc"; content:"RG93bmxvYWRGaWxl"; content:"V2ViQ2xpZW50"; content:"aW8uRmlsZ"; reference:url,securingtomorrow.mcafee.com/mcafee-labs/apt28-threat-group-adopts-dde-technique-nyc-attack-theme-in-latest-campaign/; classtype:trojan-activity; sid:2024974; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_11_07, deployment Perimeter, signature_severity Major, tag Web_Client_Attacks, updated_at 2019_07_26;)