Stateful Windows RPC attack-surface research for AI agents: 22 tools on NtObjectManager.
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π δΈζη
A Model Context Protocol server that gives an AI agent live, stateful access to Windows RPC attack-surface research, built on James Forshaw's NtObjectManager (NtCoreLib).
Three things a generic PowerShell MCP cannot do β and the reason this exists:
RpcServer objects and connected RPC clients alive across tool calls:
rpc_connect once, rpc_call many times (auth handshakes, context-handle
chains, session variables survive).rpc_vm_exec keeps variables and connected RPC clients alive
across calls through a single persistent guest runspace, never a fresh shell
per call (the vmrun fallback is reported as stateful: false).ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
β AI Agent (Claude Code / OpenCode / any MCP client) β
β β MCP (stdio, 24 tools) β
β βΌ β
β server.py ββ snippets.py (PS templates, @@TOKEN@@ + ps_str escape)β
β β β
β βΌ β
β ps_engine.py ββ persistent powershell.exe (base64 + __MCP_DONE__) β
β β state: $RPCMCP = @{ Servers; Clients; vars } β
β βΌ β
β NtObjectManager / NtCoreLib βββΊ RPC runtime (ALPC / pipe / TCP) β
ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
| Tool | Purpose |
|---|---|
rpc_parse(file, symbol_path?) | Parse a PE for RPC servers, cache (keys file_N) |
rpc_state() | Cached servers + live sessions |
rpc_get_interface(key) | Procedures, NDR params, context handles, strictness |
rpc_query_endpoints(ifid?, search_binding?, find_alpc_port?) | EPM query (local or remote) |
rpc_running_servers(pid?/service?) | Live process/service enumeration |
rpc_connect(session, key, binding?, auth?) | Generate + connect client (stateful) |
rpc_methods(session) | Signatures with opnum mapping |
rpc_call(session, method, args_json, store_as?) | Reflection invoke; {"__var__"} passes stored objects |
rpc_disconnect(session) | Drop session |
| Tool | Purpose |
|---|---|
rpc_vm_exec(ps, timeout?, vm?) | Run PowerShell inside a lab VM; state survives across calls (persistent guest runspace) |
rpc_vm_start_listener(vm?) | Deploy/start the persistent guest HTTP engine (vm_listener.ps1) |
| Tool | Methodology source |
|---|---|
rpc_scan_context_handles(paths) | Context-handle type confusion β CVE-2025-48815 pattern (whereisk0shl 2026) |
rpc_inventory(paths?, limit?) | Attack-surface inventory + EPM cross-check β MS-RPC-Fuzzer phase 1 (CVE-2025-26651) |
rpc_fuzz(session, dry_run=True) | Primitive-only default-value fuzzing with ok/denied/error classification β dry-run by default |
rpc_find_hijackable() | Unregistered interfaces of stopped services β EPM poisoning / RPC-Racer (CVE-2025-49760/59200/59230) |
rpc_etw_unreachable(duration, trigger_script?) | Clients calling dead servers β PhantomRPC (Kaspersky 2026), admin required |
rpc_interface_security(key) | ALPC SD / anonymous-ACE audit β MS-NRPC null session (SafeBreach/Securelist 2025) |
rpc_decode_flags(flags) | RpcServerRegisterIf3 flag bitmask decoding |
rpc_format_client(key) | Export generated C# client source (offline grep workflow) |
rpc_new_struct(session, type, store_as) | Build NDR complex types as session vars |
rpc_alpc_squat(name, duration) | ALPC port squat + connection capture (race validation primitive) |
rpc_accessible_tasks() | User-startable tasks (Dark-Elevator chain material, CVE-2026-66804 pattern) |
rpc_vars / rpc_clear_cache | Session-variable and cache management (eviction cap 150) |
Every tool call is appended to output/mcp_audit.log.
| Candidate | Result |
|---|---|
srvsvc.dll 98716d03β¦ flagged HIGH | Identified as XactSrv (XsOpenPrinter/XsClosePrinter/XsAddJob/XsScheduleJob) β single printer-handle type; live probe: non-admin connect OK but XsOpenPrinter β ACCESS_DENIED (authorization gate works). Scanner false-positive mode documented |
ssdpsrv.dll (CVE-2025-48815 original) | All 20 context handles strict β patched state on current builds |
| 51-module sweep | 31 findings, 6 HIGH, all "one producer β many consumers"; NDR layer cannot prove multi-type handles (needs RE) |
| EPM hijack surface | 10 stopped services with unregistered interfaces (AppIDSvc, ClipSVC, dcsvcβ¦) |
| Task chains | 44 user-startable SYSTEM tasks inventoried |
| Verdict | No confirmable exploitable vuln on the tested host β with per-step evidence |
# 1) Prerequisites (one-time)
Install-Module NtObjectManager -Scope CurrentUser -Force
pip install -r requirements.txt # mcp>=1.2.0 (1.x / 2.x compatible)
# 2) Verify β three suites, all green
python tests\smoke_test.py # 17 checks (live MCP stdio round-trip)
python tests\var_test.py # 10 checks (store_as / __var__ mechanics)
python tests\audit.py # 43 checks (edge cases, hostile paths, concurrency)
# 3) Run the server
python server.py # stdio MCP
Claude Code:
claude mcp add ntobjectmanager-rpc -- python C:\path\to\ntobjmanager-mcp\server.py
Any MCP client (e.g. OpenCode opencode.json):
{
"mcp": {
"ntobjectmanager-rpc": {
"type": "local",
"command": ["python", "C:\\path\\to\\ntobjmanager-mcp\\server.py"],
"enabled": true
}
}
}
1. rpc_parse C:\Windows\System32\target.dll [symbol_path optional]
2. rpc_scan_context_handles ["C:\\Windows\\System32\\target.dll"]
3. rpc_get_interface target_0 β producer ([out] ctx) / consumer ([in] ctx) pairs
4. rpc_connect s1 target_0 β auto-discovers binding via EPM
5. rpc_methods s1 β opnum-mapped signatures
6. rpc_call s1 XsOpenPrinter-like args store_as="h" β keep the raw handle object
7. rpc_call s1 XsClosePrinter-like [{"__var__":"h"}] β feed it to the other type
store_as / {"__var__"} is the core chain primitive: RPC return objects flow
between calls without serialization round-trips, which is exactly what
producerβconsumer handle-confusion testing needs.
ntobjmanager-mcp/
βββ server.py # 24 MCP tools + audit logging wrapper
βββ snippets.py # PowerShell templates (@@TOKEN@@ render + ps_str escaping)
βββ ps_engine.py # Persistent engine: base64 cmds + __MCP_DONE__ markers, timeouts
βββ wrapper.ps1 # PS-side loop (state lives in $RPCMCP)
βββ vm_listener.ps1 # Persistent guest HTTP bridge (stateful VM exec)
βββ tests/
β βββ smoke_test.py # 17 checks β live stdio end-to-end
β βββ var_test.py # 10 checks β store_as/__var__ object passing
β βββ audit.py # 43 checks β hostile inputs, concurrency, engine kill/restart
β βββ hunt.py # Full dogfood hunting round (safe policy)
β βββ hunt2_static.py # Deep-dive: symbols + producer/consumer map
β βββ hunt2_wide.py # 51-module sweep
β βββ hunt2_probe.py # Safe runtime probes (exposure / task cross-ref)
βββ ARCHITECTURE.md # Engine protocol + design decisions
βββ CHANGELOG.md # Decision history (R1βR13)
βββ SECURITY.md # Authorized-use policy + MSRC disclosure
βββ CONTRIBUTING.md # Development invariants
βββ LICENSE # MIT
| Claim | Status |
|---|---|
| Stateful clients across tool calls | Yes β persistent engine + $RPCMCP |
| Stateful execution inside a lab VM | Yes β one persistent guest runspace (rpc_vm_exec); the vmrun fallback is stateless |
| Context-handle chaining (producer β consumer) | Yes β store_as / __var__ raw-object passing |
| Auto-confirm type confusion | No β NDR cannot prove distinct handle types; verify via RE (see XactSrv case) |
| Full rogue-RPC hosting | No β NtObjectManager 2.0.1 ships no server builder; rpc_alpc_squat covers race-capture only |
| ETW tracing / ALPC SDDL | Requires admin (logman / SeDebugPrivilege) |
| Symbol-resolved procedure names | Environment-dependent (symsrv chain); heuristic fallback names otherwise |
| Runs anywhere but Windows PS 5.1 | Not yet (pwsh 7 untested) |
For lawful security research, education, and authorized testing only.
rpc_call invokes real RPC methods and can crash services β run it against an
isolated VM, never a production or daily-driver host. Vulnerabilities found
through this tool must follow responsible disclosure (MSRC).
MIT β Copyright (c) 2026 ntobjmanager-mcp Contributors