# exploit_build_format_string

Generate format string exploit payload for arbitrary write. Uses %hn (2-byte) writes for reliability. Returns hex payload and reliability assessment.

Agent View of the PolicyLayer registry record for `exploit_build_format_string`. HTML page: https://policylayer.com/tools/io-github-vmoranv-jshookmcp/exploit-build-format-string

## Facts

- Tool: `exploit_build_format_string`
- Server: Jshookmcp (`@jshookmcp/jshook`) — https://policylayer.com/tools/io-github-vmoranv-jshookmcp.md
- Install: `npx -y @jshookmcp/jshook`
- Homepage: https://github.com/vmoranv/jshookmcp
- Risk category: Execute (High 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": "exploit_build_format_string",
    "arguments": {}
  }
}
```

## Why exploit_build_format_string is rated High

Format string exploits enable arbitrary writes to memory and can lead to code execution, privilege escalation, or system compromise. This tool explicitly builds exploit payloads designed for 'arbitrary write' operations. While the tool itself does not execute the payload, it generates attack code intended to execute arbitrary operations on a target system.

From the tool's own definition: "Tool name explicitly contains 'exploit_build_format_string' and description states it 'Generate[s] format string exploit payload for arbitrary write.' Format string exploits are used to trigger arbitrary code execution or memory corruption by crafting…"

## Use case

AI agents invoke exploit_build_format_string to trigger actions in Jshookmcp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "exploit_build_format_string": {
      "limits": [
        {
          "counter": "exploit_build_format_string_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Jshookmcp (735)

- `adb_uninstall` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/adb-uninstall.md
- `cleanup_artifacts` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/cleanup-artifacts.md
- `clear_all_caches` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/clear-all-caches.md
- `clear_collected_data` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/clear-collected-data.md
- `dart_destroy_session` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/dart-destroy-session.md
- `exploit_cache_clear` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/exploit-cache-clear.md
- `exploit_cache_invalidate` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/exploit-cache-invalidate.md
- `extension_uninstall` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/extension-uninstall.md
- `ghidra_decompile` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/ghidra-decompile.md
- `ida_decompile` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/ida-decompile.md
- `jadx_decompile_apk` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/jadx-decompile-apk.md
- `manual_token_cleanup` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/manual-token-cleanup.md
- `memory_antidetection` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/memory-antidetection.md
- `memory_batch_edit` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/memory-batch-edit.md
- `memory_scan_session` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/memory-scan-session.md
- `memory_unregister_type` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/memory-unregister-type.md
- `nemu_destroy_session` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/nemu-destroy-session.md
- `page_cookies` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/page-cookies.md
- `page_local_storage` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/page-local-storage.md
- `page_session_storage` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/page-session-storage.md
- `proxy_clear_logs` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/proxy-clear-logs.md
- `proxy_clear_rules` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/proxy-clear-rules.md
- `proxy_remove_rule` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/proxy-remove-rule.md
- `reset_token_budget` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/reset-token-budget.md
- `session_progress_clear` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/session-progress-clear.md
- `snapshot_restore` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/snapshot-restore.md
- `tls_keylog_seal` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/tls-keylog-seal.md
- `v8_heap_snapshot_delete` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/v8-heap-snapshot-delete.md
- `webhook` — Destructive — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/webhook.md
- `activate_tools` — Execute — https://policylayer.com/tools/io-github-vmoranv-jshookmcp/activate-tools.md
- …and 705 more: https://policylayer.com/tools/io-github-vmoranv-jshookmcp.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=io-github-vmoranv-jshookmcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-vmoranv-jshookmcp