Rule History

alert tcp any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET EXPLOIT Apache log4j RCE Attempt - lower/upper TCP Bypass M1 (CVE-2021-44228)"; flow:established,to_server; content:"%7bjndi%3a"; nocase; fast_pattern; pcre:"/^(l|r|d|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)(l|r|d)(\x7d|%7d))(d|n|m|(\x24|%24)(\x7b|%24)(lower|upper)(\x3a|%3a)(d|n|m)(\x7d|%7d))(a|i|s|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)(a|i|s)(\x7d|%7d))(p|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)p(\x7d|%7d))/Ri"; reference:cve,2021-44228; classtype:attempted-admin; sid:2034659; rev:2; metadata:attack_target Server, created_at 2021_12_11, cve CVE_2021_44228, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag Exploit, tag CISA_KEV, updated_at 2021_12_14, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;)