Emerging Threathightest

Log4j RCE CVE-2021-44228 Generic

Detects exploitation attempt against log4j RCE vulnerability reported as CVE-2021-44228 (Log4Shell)

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Florian Roth (Nextron Systems)Created Fri Dec 10Updated Sun Feb 065ea8faa8-db8b-45be-89b0-151b84c827022021

Emerging Threat

Active Threat

Developed to detect an active or emerging threat. Prioritize investigation of any alerts and correlate with threat intelligence.

Log Source

Web Server Log

CategoryWeb Server Log← raw: webserver

HTTP access logs from web servers capturing request paths, methods, and status codes.

Detection Logic

detection:
    keywords:
        - '${jndi:ldap:/'
        - '${jndi:rmi:/'
        - '${jndi:ldaps:/'
        - '${jndi:dns:/'
        - '/$%7bjndi:'
        - '%24%7bjndi:'
        - '$%7Bjndi:'
        - '%2524%257Bjndi'
        - '%2F%252524%25257Bjndi%3A'
        - '${jndi:${lower:'
        - '${::-j}${'
        - '${jndi:nis'
        - '${jndi:nds'
        - '${jndi:corba'
        - '${jndi:iiop'
        - 'Reference Class Name: foo'
        - '${${env:BARFOO:-j}'
        - '${::-l}${::-d}${::-a}${::-p}'
        - '${base64:JHtqbmRp'
        - '${${env:ENV_NAME:-j}ndi${env:ENV_NAME:-:}$'
        - '${${lower:j}ndi:'
        - '${${upper:j}ndi:'
        - '${${::-j}${::-n}${::-d}${::-i}:'
    filter:
        - 'w.nessus.org/nessus'
        - '/nessus}'
    condition: keywords and not filter