alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Xunpf.A Retrieving DLL"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/web_"; fast_pattern; content:".jpg"; pcre:"/\/web_[0-9A-F]{12}\.jpg$/"; http.header_names; content:!"Referer|0d 0a|"; reference:md5,dfb7dd8b6975b73dc9c731319a05f86d; classtype:trojan-activity; sid:2020601; rev:4; metadata:created_at 2015_03_04, signature_severity Major, updated_at 2020_09_29;)