alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Ixeshe/Mecklow Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:!"&"; content:"."; content:"sp?"; distance:1; within:3; pcre:"/\/[A-Z0-9]+\.[aj]sp\?[a-zA-Z0-9+/\x20=]+$/"; http.user_agent; content:"MSIE 5.01|3b 20|Windows NT 5.0|29|"; fast_pattern; http.header_names; content:!"Accept"; content:!"Referer"; reference:url,www.microsoft.com/security/portal/Threat/Encyclopedia/Entry.aspx?Name=Backdoor%3aWin32%2fMecklow.A&ThreatID=-2147325849; reference:md5,3422e76cf4c99ec1091f8c342a3aedaa; reference:url,www.kahusecurity.com/2011/apec-spearphish-2/; classtype:command-and-control; sid:2018379; rev:12; metadata:created_at 2011_04_26, signature_severity Major, updated_at 2020_08_17;)