Rule History

alert tcp any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET EXPLOIT Apache log4j RCE Attempt - 2021/12/13 Obfuscation Observed (tcp) (CVE-2021-44228)"; flow:established,to_server; content:"%7b"; nocase; fast_pattern; pcre:"/^(j|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)j(\x7d|%7d)|(\x24|%24)(\x7b|%7b)(\x3a|%3a){1,2}\-j(\x7d|%7d))(n|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)n(\x7d|%7d)|(\x24|%24)(\x7b|%7b)(\x3a|%3a){1,2}\-n(\x7d|%7d))/Ri"; content:"|3a|"; distance:0; pcre:"/^(l|r|d|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)(l|r|d)(\x7d|%7d)|(\x24|%24)(\x7b|%7b)(\x3a|%3a){1,2}\-(l|r|d)(\x7d|%7d))(d|n|m|(\x24|%24)(\x7b|%7b)(lower|upper)\x3a(d|n|m)(\x7d|%7d)|(\x24|%24)(\x7b|%7b)(\x3a|%3a){1,2}\-(d|n|m)(\x7d|%7d))(a|i|s|(\x24|%24)(\x7b|%7b)(lower|upper)(\x3a|%3a)(a|i|s)(\x7d|%7d)|(\x24|%24)(\x7b|%7b)(\x3a|%3a){1,2}\-(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:2034671; rev:2; metadata:attack_target Server, created_at 2021_12_12, 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;)