alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Arid Viper APT Possible User-Agent (Skype)"; flow:established,to_server; http.user_agent; bsize:5; content:"Skype"; nocase; fast_pattern; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; content:"|0d 0a|remote_user|0d 0a|"; reference:url,trendmicro.com/cloud-content/us/pdfs/security-intelligence/white-papers/wp-operation-arid-viper.pdf; classtype:targeted-activity; sid:2020442; rev:6; metadata:created_at 2015_02_17, confidence Medium, signature_severity Major, updated_at 2024_04_29;)