# reg_write

Write registry value. Auto-selects client.

Agent View of the PolicyLayer registry record for `reg_write`. HTML page: https://policylayer.com/tools/0xyg3n-claude-c2/reg-write

## Facts

- Tool: `reg_write`
- Server: Claude C2 (`0xyg3n/claude-c2`) — https://policylayer.com/tools/0xyg3n-claude-c2.md
- Homepage: https://github.com/0xyg3n/claude-c2
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "reg_write",
    "arguments": {}
  }
}
```

## Why reg_write is rated Medium

Registry writes are reversible modifications to system configuration that can significantly impact system behavior, security settings, and application functionality. While not irreversible like deletion (Destructive) or involving financial transactions (Financial), and not executing arbitrary code (Execute), this is clearly a Write operation.

From the tool's own definition: "Tool name is 'reg_write' with description 'Write registry value. Auto-selects client.' The function explicitly writes to Windows Registry, a critical system configuration store."

## Use case

AI agents use reg_write to create or update resources in Claude C2, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Claude C2 environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Claude C2:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "reg_write": {
      "limits": [
        {
          "counter": "reg_write_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Claude C2 (93)

- `kill` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/kill.md
- `mv` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/mv.md
- `persist_remove` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/persist-remove.md
- `reg_delete` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/reg-delete.md
- `rm` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/rm.md
- `timestomp` — Destructive — https://policylayer.com/tools/0xyg3n-claude-c2/timestomp.md
- `amsi_bypass` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/amsi-bypass.md
- `bypassuac` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/bypassuac.md
- `defender_exclude` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/defender-exclude.md
- `etw_patch` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/etw-patch.md
- `execute_assembly` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/execute-assembly.md
- `firewall_rule` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/firewall-rule.md
- `generate_payload` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/generate-payload.md
- `get_payload` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/get-payload.md
- `getsystem` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/getsystem.md
- `inject` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/inject.md
- `keylog_start` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/keylog-start.md
- `keylog_stop` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/keylog-stop.md
- `mcp_add_tool` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/mcp-add-tool.md
- `mcp_append_code` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/mcp-append-code.md
- `mcp_restart` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/mcp-restart.md
- `mimikatz` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/mimikatz.md
- `persist_registry` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/persist-registry.md
- `persist_schtask` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/persist-schtask.md
- `persist_service` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/persist-service.md
- `persist_startup` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/persist-startup.md
- `persist_wmi` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/persist-wmi.md
- `portscan` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/portscan.md
- `powershell` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/powershell.md
- `privesc_check` — Execute — https://policylayer.com/tools/0xyg3n-claude-c2/privesc-check.md
- …and 63 more: https://policylayer.com/tools/0xyg3n-claude-c2.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=0xyg3n-claude-c2 · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/0xyg3n-claude-c2