/hunt-ntlm-info

name: hunt-ntlm-info
description: "Hunt NTLM/Negotiate information disclosure on internet-reachable IIS/SharePoint/Exchange. Anonymous NTLM Type-2 challenge capture leaks NetBIOS domain, internal DNS forest, computer name, AD timestamp via AV_PAIRS structure. Default Windows-installer hostnames (WIN-XXXXXXXXXXX pattern) signal lazy provisioning. Use when target advertises `WWW-Authenticate: NTLM` or `Negotiate` headers anonymously."
sources: github, authorized-engagement
report_count: 1

Crown Jewel Targets

NTLM info disclosure is a **Medium-severity finding when chained to context** — the leak itself is intentional protocol behavior (RFC-compliant NTLMSSP challenge), but on internet-exposed enterprise infrastructure it provides exact reconnaissance for the next stage of an attack. Highest-value targets:

• **Internet-reachable IIS / SharePoint / Exchange / OWA** with dual-auth (Forms + NTLM, or NTLM + Kerberos)
• **Citrix NetScaler / VMware Horizon View** internet-facing gateways with NTLM-backed AD auth
• **Lync / Skype for Business / Teams On-Prem** edge servers
• **WSUS / Windows Update Services** with NTLM-protected admin paths
• **CIFS-style fileshare proxies** (HCL Sametime, IBM Notes Domino) that proxy NTLM
• **Legacy SharePoint farms** that left NTLM enabled on the public-zone IIS binding

**What makes this pay:**

• Internal AD domain disclosure (parent-forest mapping, e.g. `customer.parent-corp.example` → tenant inside corporate-AD tree)
• Default-Windows-hostname disclosure (`WIN-XXXXXXXXXXX` pattern signals rushed provisioning → likely default service-account passwords)
• Timestamp leak (used in NTLMv2 hash cracking acceleration)
• Direct attack-map enrichment for credential spraying combined with `hunt-auth-bypass` Legacy-Protocol Matrix

---

Attack Surface Signals

**Response headers signaling NTLM availability:**

WWW-Authenticate: NTLM
WWW-Authenticate: Negotiate
WWW-Authenticate: NTLM, Negotiate
WWW-Authenticate: Negotiate, NTLM

**URL patterns where NTLM is commonly exposed:**

/_api/web/CurrentUser                  (SharePoint REST)
/_vti_bin/*.asmx                       (SharePoint legacy SOAP)
/EWS/Exchange.asmx                     (Exchange Web Services)
/Autodiscover/Autodiscover.xml         (Exchange autodiscover)
/owa/                                  (Outlook Web App)
/Microsoft-Server-ActiveSync           (ActiveSync)
/PowerShell                            (Exchange Mgmt Shell over HTTPS)
/api/v3/                               (TeamCity, Atlassian)
/wsus/                                 (Windows Server Update Services)
/manager/html                          (some Tomcat behind IIS)
/iisstart.htm                          (default IIS, sometimes reveals NTLM upstream)

**Tech-stack signals:**

• IIS on the public internet (almost always NTLM-capable, even if Forms is the front)
• SharePoint Web Front End (almost always dual-auth Forms + NTLM)
• Exchange edge transport
• Server header `Microsoft-HTTPAPI/2.0`, `Microsoft-IIS/*`, `IIS/*`

---

Step-by-Step Hunting Methodology

1. **Probe every anonymous endpoint for `WWW-Authenticate: NTLM`.** Send a vanilla GET and inspect response headers. If NTLM is offered, proceed.

2. **Send a valid NTLMSSP Type-1 message anonymously.** The Type-1 base64 below requests NetBIOS-domain and Workstation info from the server:

   Authorization: NTLM TlRMTVNTUAABAAAAB4IIogAAAAAAAAAAAAAAAAAAAAAGAbEdAAAADw==

This is the standard test Type-1 with negotiate flags `NTLMSSP_NEGOTIATE_UNICODE | NTLMSSP_NEGOTIATE_OEM | NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_ALWAYS_SIGN | NTLMSSP_NEGOTIATE_KEY_EXCH | NTLMSSP_NEGOTIATE_56 | NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_TARGET_INFO`. The `OS Version` field (`06 01 B1 1D 00 00 00 0F`) is Windows 7 build 7601 — accepted by virtually every NTLM responder.

3. **Use a keep-alive raw socket, not Python requests / curl one-shot.** Most HTTP libraries close the connection between the Type-1 send and Type-2 reception. Use one of:

• Burp Repeater with `Connection: keep-alive` set explicitly
• Burp `mcp__burp__send_http1_request` (handles keep-alive natively)
• Python raw `socket` + `ssl.wrap_socket` (see Payload section)

4. **Parse the Type-2 challenge from the `WWW-Authenticate: NTLM <base64>` response header.** Base64-decode the value. The structure is NTLMSSP per MS-NLMP:

• Bytes 0-7: literal `NTLMSSP\0`
• Bytes 8-11: MessageType = `\x02\x00\x00\x00`
• Bytes 12-19: TargetName SecurityBuffer (len, alloc, offset)
• Bytes 20-23: NegotiateFlags
• Bytes 24-31: Server Challenge (8 bytes — useful for offline cracking)
• Bytes 40-47: TargetInfo SecurityBuffer (len, alloc, offset)
• TargetInfo body: `AV_PAIRS` array of (AvId u16, AvLen u16, Value)

5. **Decode the AV_PAIRS.** The AvIds you care about:

• `1` = NetBIOS Computer Name
• `2` = NetBIOS Domain Name
• `3` = DNS Computer Name (FQDN of the responding server)
• `4` = DNS Domain Name (the AD domain)
• `5` = DNS Tree Name (the AD forest root)
• `7` = Timestamp (FILETIME, useful for NTLMv2 hash relay / cracking)
• `9` = Target Name (in newer NTLMSSP)

6. **Map findings to severity tier:**

• Internet-exposed + default `WIN-XXXXXXXXXXX` hostname + corporate-AD-tree disclosure → **Medium**
• Internet-exposed + named-server hostname (`SPWEB01.corp.example`) + corporate-AD-tree → **Low-Medium**
• Intranet-only + any disclosure → **Informational**
• Combine with `hunt-auth-bypass` Legacy-Protocol Matrix findings on the same host → **upgrade the auth-bypass finding's severity** since the attacker has UPN/SAM format ready

7. **Check the timestamp.** If `AV[7]` returns a current FILETIME within ~5s of `Date:` header, the system clock is synced — useful intel for Kerberos golden-ticket forging (out of bug-bounty scope but red-team relevant).

8. **Cross-reference with subdomain enum.** The DNS Tree name often reveals the *parent forest* — e.g. `customer.