alert http1 $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Kriptovor External IP Lookup checkip.dyndns.org"; flow:established,to_server; urilen:1; http.method; content:"GET"; http.host; bsize:18; content:"checkip.dyndns.org"; fast_pattern; http.user_agent; content:"Mozilla/5.0 (Windows|3b 20|U|3b 20|Windows NT 5.1|3b 20|en-US|3b 20|rv:x.xx) Gecko/20030504 Mozilla Firebird/0.6"; startswith; http.header_names; content:!"|0d 0a|Referer|0d 0a|"; content:!"|0d 0a|Connection|0d 0a|"; content:"|0d 0a|Host|0d 0a|"; startswith; reference:url,fireeye.com/blog/threat-research/2015/04/analysis_of_kriptovo.html; reference:md5,00e3b69b18bfad7980c1621256ee10fa; classtype:external-ip-check; sid:2020886; rev:11; metadata:attack_target Client_Endpoint, created_at 2015_04_09, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, updated_at 2024_11_26, mitre_tactic_id TA0007, mitre_tactic_name Discovery, mitre_technique_id T1614, mitre_technique_name System_Location_Discovery;)