# Phase 21 (Track M.3) — Rack/Rails middleware vuln fixture. # # `AuditMiddleware#call(env)` splices `env['nyx.payload']` into a shell # command — classic Rack-middleware cmdi shape. class AuditMiddleware def initialize(app) @app = app end def call(env) payload = env['nyx.payload'] || env['QUERY_STRING'].to_s # SINK: tainted env value concatenated into shell command. system("echo " + payload.to_s) @app.call(env) end end