AI agents call ownership_block to retrieve information from Open Proxy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool appears designed to retrieve shareholding block information—a read-only query operation. The 'medium' severity reflects that ownership data could inform trading decisions or reveal competitive intelligence, but the tool itself performs no irreversible actions, code execution, or financial transfers. Confidence is 0.7 rather than higher due to the missing description.
From the tool's definition Tool name 'ownership_block' and server context indicate retrieval of ownership/shareholding data for Korean stocks.
Documented attack patterns abuse exactly the kind of access ownership_block gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open Proxy, and nothing reaches the server without passing your rules. This is the rule we recommend for ownership_block:
{
"version": "1",
"default": "deny",
"tools": {
"ownership_block": {}
}
}ownership_block is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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ownership_block. It is categorised as a Read tool in the Open Proxy MCP Server, which means it retrieves data without modifying state.
Register the Open Proxy MCP server in PolicyLayer and add a rule for ownership_block: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Open Proxy. Nothing to install.
ownership_block is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the ownership_block rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for ownership_block. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
ownership_block is provided by the Open Proxy MCP server (marcoyou/open-proxy-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open Proxy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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54 Open Proxy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.