alert dns $HOME_NET any -> any any (msg:"ET MALWARE Suckfly/Nidiran Backdoor DNS Lookup"; dns.query; content:"microsoft-security-center.com"; startswith; nocase; endswith; fast_pattern; reference:url,symantec.com/security_response/earthlink_writeup.jsp?docid=2015-120123-5521-99; classtype:trojan-activity; sid:2022626; rev:6; metadata:created_at 2016_03_16, confidence Medium, signature_severity Major, updated_at 2024_04_13;)