SKILL: Modern Initial Access

Metadata

• Skill Name: initial-access
• Folder: offensive-initial-access
• Source: https://github.com/SnailSploit/offensive-checklist/blob/main/initial-access.md

Description

Initial access techniques checklist: phishing (spear/smishing), credential stuffing, exposed service exploitation, supply chain attacks, watering hole, VPN/RDP brute force, public-facing application exploitation. Maps to MITRE ATT&CK TA0001. Use when planning initial access phases of red team engagements.

Trigger Phrases

Use this skill when the conversation involves any of: initial access, phishing, spear phishing, credential stuffing, exposed service, supply chain, watering hole, VPN brute force, RDP attack, MITRE TA0001, initial foothold

Instructions for Claude

When this skill is active:

1. Load and apply the full methodology below as your operational checklist
2. Follow steps in order unless the user specifies otherwise
3. For each technique, consider applicability to the current target/context
4. Track which checklist items have been completed
5. Suggest next steps based on findings

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Full Methodology

Modern Initial Access

Introduction

Typical Initial Access Vectors

• Email with malware attached/linked
  • Most attacks using attached malware won't work
  • Out of the box protection may not cover PDF, ISO, IMG, HTML, SVG, PPTM, PPSM, ACCDE
  • Most URL-based attacks do work
  • domain's reputation, age, category should be sound
  • domain should use https
  • limit number of GET elements and their names
  • use HTML Smuggling to evade
  • get your domain warmed up (send some legitimate emails first with no attachment and links)
  • Advanced attacks may involve delivering backdoored trusted applications (e.g., older Electron apps with V8 exploits) via phishing to bypass application control like WDAC.
• Spear-phishing/ phishing / stealing valid credentials
  • Check your mail with Phishious before sending it to your victim
  • use decode-spam-headers to analyze returned SMTP headers
  • Be aware that default Microsoft Office settings now block macros in files downloaded from the internet (marked with MOTW). Success often requires significant social engineering to convince users to bypass these protections or using alternative delivery methods (e.g., containers that don't propagate MOTW, signed add-ins).
  • images and link increase spam score, be wary of it
  • don't use no-reply like usernames
  • send through GoPhis -> AWS SOCAT :587 -> smtp.gmail.com -> @target.com
  • link to websites on trusted domains, like cloud-facing resources
  • make sure your webserver blocks automated bots
• Deep‑fake voice or video social‑engineering calls (help‑desk or executive impersonation) to obtain password resets or approve MFA prompts. Generative‑AI tools make cloning voices trivial.
• Business Email Compromise (BEC) / OAuth consent phishing that targets finance or vendor‑portal users, yielding cloud‑token access even where MFA is enabled.
• Malicious OneNote .one attachments and OneDrive "Add to Shortcut" abuse: embedded HTA/JS payloads bypass Office macro blocking and spread via cloud sync.
• Excel blocks untrusted Internet-origin XLL add-ins by default (M365, 2023+). Smuggled XLLs inside containers may still be blocked once MOTW propagates.
• Malicious browser extensions (Chrome, Edge, Firefox) delivered through fake Web Store listings; hijack session cookies or inject scripts into authenticated SaaS sessions.
• attackers register malicious cloud apps and trick users into granting scopes, giving token-based access that bypasses MFA
• Reusing stolen credentials against external single factor VPN, gateways, etc
• Password Spraying against Office365, custom login pages, VPN gateways
• Exposed RDP with weak credentials and lacking controls
• Unpatched known vulnerable perimeter device, application bugs, default credentials, etc
• Rarely HID-emulating USB sticks
• WiFi Evil Twin -> Route WPA2 Enterprise -> NetNTLMv2 hash cracking -> authenticated network access -> Responder
• Plugging into on-premises LAN -> Responder/mitm6/Ldaprelayx
• SEO poisoning / paid‑search malvertising (e.g., fake PuTTY & WinSCP ads, dominant loader delivery 2024–25) and "quishing" PDFs whose QR codes redirect victims to mobile OAuth login pages
• Consent‑/token‑phishing and Adversary‑in‑the‑Middle (AiTM) proxy kits that steal OAuth session cookies or proxy MFA (e.g., EvilProxy, Tycoon, Dadsec). These vectors bypass MFA by tricking users into granting access to rogue Azure AD / Google Workspace apps.
• Supply‑chain compromise of developer ecosystems:
  • malicious NPM / PyPI typosquat packages
  • poisoned GitHub Actions or CI/CD secrets exfiltration
  • container‑registry deception (imageless Docker Hub repos or curl | bash installers).
  • First contact often occurs on developer workstations.
• Mass‑exploited perimeter and edge‑device zero‑days (e.g., Ivanti Connect Secure (such as CVE-2023-46805, CVE-2024-21887), MOVEit Transfer (such as CVE-2023-34362), Citrix Bleed) enabling unauthenticated remote code execution before credentials come into play. Maintain a live "current CVEs exploited‑in‑the‑wild" table and apply virtual patching/WAF rules where upgrades lag.
• Cloud & Kubernetes misconfigurations:
  • exposed S3 buckets allowing upload‑then‑execute objects
  • SSRF into EC2 IMDSv1 or GCP metadata to steal instance credentials
  • open Kubernetes API/Argo CD dashboards, and leaked Azure SAS tokens that grant cross‑tenant data extraction.
  • OIDC Workload Identity Federation exposed: stolen GKE/EKS service‑account tokens grant cross‑cluster privilege escalation.
  • AWS STS credentials embedded in shareable URLs (GetFederationToken, presigned S3, etc.) leak temporary keys to attackers.
• Mobile initial‑access vectors:
  • smishing or WhatsApp/Telegram lures
  • QR‑code invoice/resumé phishing that lands on mobile browsers
  • rogue Mobile Device Management (MDM) enrolment profiles granting full device admin.
  • Passkey/WebAuthn phishing pages that spoof the biometric prompt to hijack FIDO sessions.
  • Sideload invitations via fake Apple TestFlight or Test Fairy links deliver malicious iOS/Android apps outside official store review.
• Collaboration‑app abuse:
  • malicious Microsoft Teams/Slack/Discord apps with overbroad OAuth scopes
  • slash‑command token vacuum
  • SharePoint Framework (SPFx) app sideloading
  • Discord/Telegram CDN links hosting first‑stage binaries.
• If WinRM over HTTPS (WinRMS, port 5986) is enabled (it's not by default) and its Channel Binding setting remains at the default "Relaxed", it becomes vulnerable to NTLM relay attacks. Relayed credentials (e.g., from coerced HTTP/SMB/LDAP) can grant RCE. Ironically, enabling WinRMS to "harden" a system by disabling HTTP WinRM (port 5985, which is relay-resistant due to internal encryption) can introduce this vulnerability. Key technical details:
  • Standard WinRM (port 5985) uses HTTP with SPNEGO; channel binding is enabled by default, so NTLM relay fails unless the attacker controls TLS.
  • WinRMS (port 5986) runs over HTTPS; if CbtHardeningLevel is not set to Strict, credentials can still be relayed despite TLS.
  • Channel Binding (CBT) can be set to None (disabled), Relaxed (optional), or Strict (required)
  • Mitigation: winrm set winrm/config/service/auth '@{CbtHardeningLevel="Strict"}'
  • Prefer Kerberos or certificate-based auth for WinRM; monitor and reduce NTLM usage.
• Exploiting misconfigured Power Platform services (e.g., Power Apps with overly permissive shared connections or abusing Power Query for native SQL execution against on-prem data gateways).

Command & Control

• Use a two-stage Mythic C2 as our command and control
• Stage one should be lean and hard to detect, it would be used for situational awareness
  • Merlin for Linux (no upstream commits since 2023, still functional)
  • Poseidon + Apfell for macOS
  • Apollo in shellcode form for Windows
    • to get rid of apollo console
    • open it via detect-it-easy, select pe and uncheck readonly
    • then select WINDOWS_GUI in Subsystem inside IMAGE_OPTIONAL_HEADER
    • also notice apollo is a 32-bit executable
  • also checkout Nimplant or others
  • Nighthawk
• Stage two should be in-memory, inline-execute and feature reach
  • Nighthawk, Cobalt Strike, etc

Exec/DLL to SHELLCODE

For detailed information on converting executables and DLLs to shellcode, including:

• Embedding shellcode into loaders
• Backdooring legitimate PE executables
• Tools like Donut, sRDI, Pe2shc and Amber
• Open-source shellcode loaders like ScareCrow and NimPackt-v1

See the Shellcode documentation.

EDR Evasion Techniques

For detailed information on EDR evasion techniques, including:

• Malware Virtualization
• API Unhooking
• Early Cascade Injection
• Killing Bit techniques
• Call Stack Obfuscation
• Sleep Obfuscation

See the EDR Evasion documentation

Modern CyberDefense Stack

• Secure Email Gateway / Email Security
  • FireEye MX
  • Cisco Email Security
  • TrendMicro for Email
  • MS Defender for Office365
• Secure Web Gateway
  • Symantec BlueCoat
  • PaloAlto Proxy
  • Zscaler
  • FireEye NX
• Secure DNS
  • Cisco Umbrella
  • DNSFilter
  • Akamai Enterprise Threat Protector
• AntiVirus
  • McAfee
  • ESET
  • Symantec
  • BitDefender
  • Kaspersky
• EDR
  • CrowdStrike Falcon
  • MS Defender for Endpoint
  • SentinelOne
  • VMware Carbon Black

Defensive quick‑wins

• Email/web controls
  • Enable Microsoft Defender for Office 365 Safe Links and Safe Attach (or vendor equivalent).
  • Block direct download of executable formats; detonate unknowns in sandbox.
• Office hardening
  • Keep "Block macros from the Internet (MOTW)" enforced; prefer trusted locations.
  • Block XLL add‑ins, unsigned COM add‑ins, and legacy Excel 4.0 macros
  • ASR rules: Block Office child processes; Block Win32 API calls from Office; Block executable content from email and webmail; Block credential stealing from LSASS.
• Browser/extension control
  • Enforce extension allowlists (Chrome/Edge/Firefox policy); disable developer mode on managed devices.
• Identity & auth
  • Enforce MFA; restrict OAuth app consent (publisher verification + admin consent workflows); tenant restrictions.
  • Prefer phishing‑resistant MFA (FIDO2/CTAP); block legacy/basic auth; monitor device‑code flow abuse.
• Endpoint policies
  • WDAC/Smart App Control or application allow‑listing for untrusted installers (MSI/MSIX/ClickOnce).
  • Monitor and restrict PowerShell Constrained Language Mode exceptions; log script block.
  • For WinRM: prefer Kerberos/certificate auth; set WinRMS channel binding to Strict: winrm set winrm/config/service/auth '@{CbtHardeningLevel="Strict"}'.

Security Controls Evasion

Perimeter Defense Evasion

Secure Web Gateway

• sensitive on
  • Domain characteristics
  • URL-fetched contents (HTML, body, javascript)
  • MIME types (where file type is allowed or not)
• can be evaded via
  • high reputation servers (cloud instances)
  • HTML smuggling

Secure DNS

• sensitive on
  • Domain categorisation, maturity, whois examination
  • Presence on real-time blocking lists, threat intelligence feeds, virustotal-alike databases
  • SSL/TLS certificate contents
• can be evaded via
  • high reputation domains (Domain fronting CDN like azure edge CDN, Cloud-based resources like AWS lambda or azure blob storage, personal cloud drives)
  • use Talos Intelligence to check reputation
  • AWS is dumber than Azure, use it

Endpoint Defense Evasion

Antivirus

• sensitive on
  • static signatures
  • heuristic signatures
  • behavioural signatures
  • trigger events on-demand -> on-write -> on-access -> on-execute -> real-time
  • proactive protection of them is weaker due to low false-positive, low impact and high stability requirements
    • before-exec: mainly cloud-reputation based examination
    • before-exec: machine learning evaluation focusing on hand-picked characteristics
    • on-exec: simulating entry point and first N instructions
    • on-exec: memory scanner sweeping process virtual memory allocations for presence of signatured threats
  • steps
    • static analysis
    • heuristic analysis
    • cloud reputation analysis + automated sandboxing / detonation
    • ML analysis
    • emulation
    • behavioural analysis
• can be evaded via
  • static analysis by writing custom malware
  • heuristic analysis by smartly blending-in with our payload
  • cloud reputation by backdooring legitimate binaries, devising malware in containers (PDF, Office docs), sticking to DLLs
  • automated sandboxing by environmental keying (only execute if something)
  • ML analysis by trial and error, hard to combat
  • emulation by time-delaying, environmental keying
  • behavioural analysis by
    • avoiding suspicious WinAPI calls
    • acting low-and-slow instead of all-at-once
    • unhooking/direct syscalls may work

EDR Evasion Techniques

For detailed information on EDR evasion techniques, including:

• Malware Virtualization
• API Unhooking
• Early Cascade Injection
• Killing Bit techniques
• Call Stack Obfuscation
• Sleep Obfuscation
• Telemetry obfuscation
• Persistence strategies
• Event correlation evasion

See the EDR Evasion documentation.

Windows Defender Bypass Techniques

For detailed information on Windows Defender bypass techniques, including ASR bypasses and custom detection rules evasion, see the EDR Evasion documentation.

Hosting Payloads

• Server Hosting our Payload must
  • Look benign, best if commonly used for file hosting
  • Have SSL/TLS certificate signed by trusted authority
  • Hard to be blocked by target (cloud based)
• Example
  • Cloud-based file storage: Office365 OneDrive, SharePoint, AWS S3, MS Azure Storage, Google Drive, FireBase Storage
  • CDN: Azure Edge CDN, StackPath, Fastly, Akamai, Google Cloud AppSpot, HerokuApp
  • Serverless Endpoints: AWS Lambda, CloudFlare Workers, DigitalOcean Apps
• use LOTS Project for help
• use LOLBINS
  • prefer DLL over EXE
  • indirect execution to circumvent EDR/AV
  • DLL Side-Loading / DLL Hijacking / COM Hijacking / XLL
• check Microsoft Block Rules to better circumvent defender

Infection Vectors and Chains

Classic File Infection Vectors

MAC

• initial access is getting harder, for example for MAC you can still bypass
  • Unsigned apps (gets through with few clicks)
  • Office Macros + .SLK Excel4 macros (constrained by gatekeeper)
  • you can use Mystikal
• Use LNK, CHM, CPL, DLL, MSI, HTML, SVG; hold Office w/macros, ISO, VHD, XSL.

Windows Script Host

• VBE, VBS, JSE, JS, XSL, HTA, WSF
• Mostly well detected and subject to AMSI detection. Effectiveness significantly reduced for Office macros due to default security settings blocking macros from the internet (MOTW).
• Viable strategies for WSH scripts (often requiring MOTW bypass or user interaction):
  • File Dropper
    • download a file from internet/ UNC share or unpack from itself
    • save the file onto workstation
    • run the file directly/indirectly via LOLBIN
  • DotNetToJScript / GadgetToJScript
    • a way to deserialize and run .NET executables in-memory
    • use BinaryFormatter to deserialize them
  • XSL TransformNode
    • simple technique to run XSL/XML files in-memory while maintaining low IOC footprint
  • XLAM Dropper
    • Macro-enabled excel add-in file
    • when dropped to %APPDATA%\Microsoft\Excel\XLSTART, they are auto-executed when starting excel
  • Microsoft Compiled Help Messages
    • can be used to run a system command whenever user browses into them
    • some used to run VBS or quietly install MSI
  • LNK
    • EXE/ZIP embedded into LNK
    • can be polyglot-ted with HTA/ISO/PDF/ZIP/RAR/7z
    • use icons to weaponize, inspect with LEcmd to make sure not disclosing MAC & hostname
    • always run through a LOLBIN like conhost.exe
  • HTML Smuggling
    • body onload callback
    • optional setTimeout delay or direct entrypoint call
    • embedded payload footprint
    • actual logic
      • create a JavaScript Blob object holding raw file data
      • if operating on IE use msSaveOrOpenBlob
      • else, create a dynamic <a style="display:none"></a> HTML node
      • invoke URL.createObjectURL() and set <a href="...">
      • set download name via <a>.download
      • programmatically click the anchor to trigger the download
    • use detect-headless to identify sandboxes
    • run anti-headless logic after some time elapses
    • Can bypass most secure gateways, but the downloaded file (e.g., ISO, ZIP, LNK, document) still faces endpoint scrutiny. If the smuggled file relies on macros (e.g., .docm), it will likely be blocked by default Office security unless the user explicitly enables content.
  • COM Hijack
• every VBA strategy requires launcher and often needs to overcome default macro security blocks:
  • WScript.Shell
  • WMI Win32_Process::Create
  • Shell(...)
  • etc

Complex Infection Chains

Containerized Malware

• Files downloaded from internet have Mark of the Web(MOTW) taint flag
• Default Behavior: Office documents having MOTW flag have their macros blocked by default, preventing automatic execution. This is a major mitigation against traditional macro-based attacks.
• You can download it from intranet or trusted locations to circumvent this (less common for initial access).
• Some container file formats do not propagate MOTW flag to inner files when extracted, providing a potential bypass:
  • ISO / IMG
  • 7zip
  • CAB
  • VHD / VHDX
  • WIM
  • check MOTW Comparison to make sure

[!Note] (Windows 11 22H2+): ISOs opened via double-click in Explorer inherit MOTW. Using Mount-DiskImage via PowerShell typically avoids propagation; validate on your build.

Chains Recipe

• In‑the‑wild sample
  • Spear-Phishing
  • Link in mail or Link in PDF
  • HTML Smuggling drops ISO or ZIP
  • ZIP contains RTLO‑tricked .EXE disguised as .PDF being legit 7‑Zip executable
    • .PDF.EXE when clicked, sideloads benign vcruntime140.dll that imports evil 7za.dll
  • ISO contains LNK + DLL
    • .LNK runs rundll32 evil.dll,SomeExport
• Delivery - convey your chain (HTML smuggling drop in drive-by download fashion)
• Container - archive bundling all infection files
  • ISO/IMG/ZIP can contain hidden files
• Trigger - some way to run our payload (LNK/CHM)
• Payload - our malware
  • Note: Macro-enabled office documents (.docm, .xlsm) are less reliable for initial execution due to MOTW blocks unless combined with social engineering or specific bypasses.
  • can be macro-enabled office document with MOTW stripped (e.g., delivered inside a container like ISO/VHD)
  • DLL/CPL/XLL to be loaded by trigger directly or indirectly with LOLBIN (XLLs also subject to MOTW blocking if downloaded directly)
  • XLAM to be copied to XLSTART for persistence & abusing office trusted path
  • MSI/MSP to run during silent installation (MOTW stripped)
  • VbaProject.OTM for outlook persistence
  • .EXE + .DLL executing through side-loading attack
• Decoy - keep your victim happy by displaying some interesting stuff

Successful Strategies

# plant evil.xlam to %APPDATA%\Microsoft\Excel\XLSTART so that next time user opens up Excel it will get loaded
cmd /c echo f | xcopy /Q/R/S/Y/H/G/I evil.ini %APPDATA%\Microsoft\Excel\XLSTART | decoy.pdf

# Plant VbaProject.otm to %APPDATA%\Microsoft\Outlook\VbaProject.OTM and alter registry so upon outlook restart VBA will be loaded and act on every new email arrived
cmd /c reg add hkcu\software\micorosft\office\16.0\outlook\security /f /v Level /t reg_dword /d 1 | echo f | xcopy /Q/R/S/Y/H/G/I evil.xlam %APPDATA%\Microsoft\Outlook\VbaProject.OTM | decoy.pdf
# corrected HKCU path
cmd /c reg add hkcu\software\microsoft\office\16.0\outlook\security /f /v Level /t reg_dword /d 1 | echo f | xcopy /Q/R/S/Y/H/G/I evil.xlam %APPDATA%\Microsoft\Outlook\VbaProject.OTM | decoy.pdf

# your ZIP/ISO/IMG will contain signed executable prone to DLL Hijacking/side-loading and appropriate malicious DLL
cmd /c DISM.exe | decoy.pdf

# load .DLL through LOLBIN
cmd /c rundll32 evil.dll,Infect | decoy.pdf

# LNK/CHM that runs PowerShell to locate own .ZIP, then unpacks ZIP contents elsewhere then changes dir into there, then registers .XLL (having stripped MOTW)

# ClickOnce deployment requires several local files; bundle into ZIP/ISO, hide them, then deploy ClickOnce followed by opening decoy.pdf

# PowerShell might use Unblock-File on .MSI and then silently install it
powershell Unblock-File evil.msi; msiexec /q /i .\evil.msi ; .\decoy.pdf

# install signed MSI and apply an unsigned MST
powershell msiexec /q /i .\Zoom-signed-installer.msi TRANSFORMS=evil.mst ; .\decoy.pdf

# run WSH script
cmd /c wscript evil.wsf | decoy.pdf

# LNK/CHM that runs PowerShell to locate its own ZIP, then unpacks ZIP contents elsewhere, changes directory and runs tasks (e.g., deploy ClickOnce)

VBA Infection Strategies

• Important Note: The effectiveness of traditional VBA macro execution on document open (AutoOpen, Document_Open) is significantly diminished due to Microsoft's default security policy blocking macros in files downloaded from the internet (MOTW). Successful execution often requires social engineering to have the user explicitly trust the document/location or alternative execution methods (like COM hijacking triggered later, Add-Ins, etc.).
• Alt+F11IM - quickly inserts VBA module into a document
• abuse path
  • execute
  • file dropper
  • COM hijack
  • DotNetToJScript
• use of WinAPI is strongly inadvisable due to detection
• GetUserNameA might be fine but things like CreateProcessA is a big no-no
• AutoOpen,Document_Open, etc can be used to auto-run our script

Attack Surface Reduction Rules

• Set of policies enforced by Microsoft Defender Exploit Guard attempting to contain malicious activities
• Defender ASR Rules
• ExtractedDefender
• commial ASR

Execute

• Most basic strategy is to simply run some command with LOLBIN. Subject to macro execution policies.
• Avoid running immediately; prefer persistence. Consider COM/DLL hijacking and always use LOLBINs.
• useful ones
  • Wscript.Shell.Exec - prefix with obf_ to facilitate later obfuscation
  • InvokeVerbEx - evades detection but sometimes doesn't work with LOLBIN
  • RDS.DataSpace - supposed to be obsolete, but still works
• use AMSITools to review AMSI events

# ev