🚨 EXPLOIT PoC — FOR SECURITY RESEARCH, VULNERABILITY ANALYSIS AND DEFENSIVE PURPOSES ONLY

🚨 PoC DE EXPLOIT — SOLO PARA INVESTIGACIÓN DE SEGURIDAD, ANÁLISIS DE VULNERABILIDADES Y FINES DEFENSIVOS

🌐 Idiomas / Languages

🇪🇸 Español
🇬🇧 English

🇪🇸 Documentación en Español

Descripción

CVE-2025-60709 es una vulnerabilidad de escalación de privilegios locales (LPE) en el controlador CLFS.sys (Common Log File System) de Windows. Permite a un atacante con ejecución de código local escalar desde usuario estándar hasta NT AUTHORITY\SYSTEM mediante un buffer overflow en el parsing de contenedores CLFS, obteniendo una primitiva de escritura arbitraria en memoria del kernel.

Este repositorio contiene dos implementaciones:

CVE-2025-60709.c — Implementación original en C (acceso directo a APIs nativas de Windows)
CVE-2025-60709.go — Port en Go (versión de demostración/educativa — NO explota vulnerabilidades reales)

🎯 Detalles de la Vulnerabilidad

🏗️ Estructura del Repositorio

CVE-2025-60709/
├── CVE-2025-60709.c    (5.3 KB, 157 líneas) — Exploit C original
├── CVE-2025-60709.go   (9.2 KB, 285 líneas) — Port Go (demo educativa)
└── README.txt          (4.2 KB, 132 líneas) — Documentación original

🔬 Análisis Técnico Detallado

Flujo de Explotación Completo

┌─────────────────────────────────────────────────────────────┐
│                    CVE-2025-60709 LPE                       │
└─────────────────────────────────────────────────────────────┘

[1] EVASIÓN DE DEFENSAS
    ├─ KillETW()   → Parchea EtwEventWrite en ntdll con RET (0xC3)
    └─ KillAMSI()  → Parchea AmsiScanBuffer en amsi.dll con RET (0xC3)

[2] HEAP GROOMING (preparación de memoria)
    └─ GroomLookaside()
       ├─ Crea 4096 archivos: C:\Windows\Temp\groom_00000.blf
       ├─ Llama CreateLogFile() + AddLogContainer() por cada uno
       └─ Agota lookaside lists → garantiza layout de heap predecible

[3] PRIMITIVA DE ESCRITURA ARBITRARIA — ClfsArbWrite(Address, Value)
    ├─ Construye buffer CLFS malformado (0x102010 bytes)
    │    ├─ Firma válida CLFS en +0x00: 0x0201
    │    ├─ Sector size shift en +0x14: 2
    │    ├─ First client region en +0x28: 0x100
    │    ├─ cbRecord OVERSIZED en +0x100: 0xFF00 (64 KB > datos reales)
    │    ├─ Marcador shadow zone en +0x9A8: 0x13371337
    │    └─ CClfsContainerContext falso en offset (0xFF00 + 0x100):
    │         ├─ pContainer = TargetAddress - 0x10
    │         └─ cbContainer = Value (dato a escribir)
    ├─ Calcula checksum CLFS correcto (driver lo valida)
    ├─ Escribe contenedor malformado → C:\Windows\Temp\evil.blf
    ├─ Crea log apuntando a evil.blf
    ├─ Llama ClfsReadRestartArea() → dispara parsing kernel
    └─ Driver desborda buffer → escribe Value en Address ✓

[4] ROBO DE TOKEN SYSTEM
    ├─ Lee EPROCESS del proceso SYSTEM via PsInitialSystemProcess
    └─ Extrae token en EPROCESS + EPROCESS_TOKEN (offset 0x4c0)

[5] ESCALACIÓN DE PRIVILEGIOS
    └─ ClfsArbWrite(CurrentEprocess + 0x4c0, SystemToken)
       └─ Sobreescribe token del proceso actual con token SYSTEM ✓

[6] EJECUCIÓN DE PAYLOAD C2
    ├─ VirtualAlloc(PAGE_EXECUTE_READWRITE)
    ├─ Copia shellcode beacon de 1789 bytes
    ├─ CreateThread() → ejecución como NT AUTHORITY\SYSTEM
    └─ Beacon C2: IPv6 + DoH → fallback Gmail drafts
       └─ sRDI + sleep obfuscation + ETW/AMSI ya parcheados

[7] PERSISTENCIA
    └─ Sleep(INFINITE) → proceso mantiene token SYSTEM

Offsets EPROCESS (Windows 11 24H2 build 26100.3485+)

⚠️ Estos offsets varían entre builds de Windows. Requieren actualización para otras versiones.

Mecanismo del Buffer Overflow en CLFS

Contenedor CLFS legítimo:
  [Header 0x100 bytes][Record: cbRecord bytes de datos reales]

Contenedor malformado (evil.blf):
  [Header válido][cbRecord=0xFF00 → kernel lee 65,280 bytes]
                          ↓
  Kernel overflow → llega a CClfsContainerContext falso
                          ↓
  pContainer  = TargetKernelAddress - 0x10
  cbContainer = ValueToWrite
                          ↓
  Driver usa estructura falsa → escribe ValueToWrite en TargetKernelAddress

Funciones Clave — `CVE-2025-60709.c`

Diferencias C vs Go

Compilación

Versión C (requiere Visual Studio Build Tools + Windows SDK):

cl /O1 /MT /link ntdll.lib advapi32.lib clfsw32.lib CVE-2025-60709.c

Versión Go (requiere Go 1.19+ en Windows x64):

go build -ldflags="-s -w" -o CVE-2025-60709.exe CVE-2025-60709.go

🛡️ Mitigaciones y Detección

Mitigaciones de Windows

Regla YARA

rule CVE_2025_60709_CLFS_LPE {
    meta:
        description = "Detects CVE-2025-60709 CLFS LPE exploit"
        author      = "KONDORDEVSECURITYCORP"
        date        = "2026-03"
        cve         = "CVE-2025-60709"
        severity    = "critical"

    strings:
        $clfs_sig   = { 01 02 00 00 }
        $magic      = { 37 13 37 13 }
        $evil_file  = "evil.blf" ascii wide
        $groom_file = "groom_" ascii wide
        $etw_func   = "EtwEventWrite" ascii wide
        $amsi_func  = "AmsiScanBuffer" ascii wide
        $token_off  = { C0 04 00 00 }       // EPROCESS_TOKEN = 0x4C0

    condition:
        3 of them
}

IOCs — Artefactos del Sistema

Detección Comportamental

ARCHIVO:   Creación masiva de *.blf en C:\Windows\Temp\ (> 100 en segundos)
ARCHIVO:   Creación de C:\Windows\Temp\evil.blf
PROCESO:   Proceso en modo REALTIME_PRIORITY + llamadas a ClfsReadRestartArea
MEMORIA:   Escritura en PAGE_EXECUTE_READWRITE + CreateThread inmediato
API:       VirtualProtect sobre EtwEventWrite o AmsiScanBuffer
KERNEL:    Acceso a PsInitialSystemProcess desde user-mode

Verificación Rápida

# Verificar archivos de grooming
Get-ChildItem C:\Windows\Temp -Filter "groom_*.blf" | Measure-Object

# Verificar archivo exploit
Test-Path C:\Windows\Temp\evil.blf

# Verificar integridad de ntdll (ETW patch)
Get-AuthenticodeSignature (Get-Process -Name notepad | Select -First 1).Path

🇬🇧 English Documentation

Description

CVE-2025-60709 is a Local Privilege Escalation (LPE) vulnerability in the Windows CLFS.sys (Common Log File System) driver. It allows an attacker with local code execution to escalate from a standard user to NT AUTHORITY\SYSTEM through a buffer overflow in CLFS container parsing, obtaining an arbitrary write primitive to kernel memory.

This repository contains two implementations:

CVE-2025-60709.c — Original C implementation (direct access to native Windows APIs)
CVE-2025-60709.go — Go port (demonstration/educational version — does NOT exploit real vulnerabilities)

🎯 Vulnerability Details

🔬 Technical Analysis

Exploitation Flow

[1] DEFENSE EVASION
    ├─ KillETW()   → Patch EtwEventWrite in ntdll with RET (0xC3)
    └─ KillAMSI()  → Patch AmsiScanBuffer in amsi.dll with RET (0xC3)

[2] HEAP GROOMING
    └─ GroomLookaside()
       ├─ Creates 4096 files: C:\Windows\Temp\groom_00000.blf
       ├─ Calls CreateLogFile() + AddLogContainer() for each
       └─ Exhausts lookaside lists → guarantees predictable heap layout

[3] ARBITRARY WRITE PRIMITIVE — ClfsArbWrite(Address, Value)
    ├─ Constructs malformed CLFS buffer (0x102010 bytes)
    │    ├─ Valid CLFS signature at +0x00: 0x0201
    │    ├─ Oversized cbRecord at +0x100: 0xFF00 (65,280 bytes)
    │    ├─ Shadow zone marker at +0x9A8: 0x13371337
    │    └─ Fake CClfsContainerContext at offset (0xFF00 + 0x100):
    │         ├─ pContainer  = TargetAddress - 0x10
    │         └─ cbContainer = Value (data to write)
    ├─ Computes valid CLFS checksum (driver validates)
    ├─ Writes malformed container → C:\Windows\Temp\evil.blf
    ├─ Creates log pointing to evil.blf
    ├─ Calls ClfsReadRestartArea() → triggers kernel parsing
    └─ Driver overflows buffer → writes Value to Address ✓

[4] SYSTEM TOKEN THEFT
    ├─ Reads SYSTEM process EPROCESS via PsInitialSystemProcess
    └─ Extracts token at EPROCESS + 0x4C0

[5] PRIVILEGE ESCALATION
    └─ ClfsArbWrite(CurrentEprocess + 0x4C0, SystemToken)
       └─ Overwrites current process token with SYSTEM token ✓

[6] C2 PAYLOAD EXECUTION
    ├─ VirtualAlloc(PAGE_EXECUTE_READWRITE)
    ├─ Copy 1789-byte shellcode beacon
    ├─ CreateThread() → runs as NT AUTHORITY\SYSTEM
    └─ Beacon: IPv6 + DoH C2 → Gmail drafts fallback
       └─ sRDI + sleep obfuscation + ETW/AMSI already patched

[7] PERSISTENCE
    └─ Sleep(INFINITE) → process keeps SYSTEM token

EPROCESS Offsets (Windows 11 24H2 build 26100.3485+)

⚠️ These offsets vary between Windows builds. Must be updated for other versions.

CLFS Buffer Overflow Mechanism

Legitimate CLFS container:
  [0x100 byte Header][Record: cbRecord bytes of real data]

Malformed container (evil.blf):
  [Valid Header][cbRecord=0xFF00 → kernel reads 65,280 bytes]
                        ↓
  Kernel overflows → reaches fake CClfsContainerContext
                        ↓
  pContainer  = TargetKernelAddress - 0x10
  cbContainer = ValueToWrite
                        ↓
  Driver uses fake structure → writes ValueToWrite to TargetKernelAddress

Key Functions — `CVE-2025-60709.c`

C vs Go Differences

Build Instructions

C version (requires Visual Studio Build Tools + Windows SDK):

cl /O1 /MT /link ntdll.lib advapi32.lib clfsw32.lib CVE-2025-60709.c

Go version (requires Go 1.19+ on Windows x64):

go build -ldflags="-s -w" -o CVE-2025-60709.exe CVE-2025-60709.go

🛡️ Mitigations and Detection

Windows Mitigations

YARA Rule

rule CVE_2025_60709_CLFS_LPE {
    meta:
        description = "Detects CVE-2025-60709 CLFS LPE exploit"
        author      = "KONDORDEVSECURITYCORP"
        date        = "2026-03"
        cve         = "CVE-2025-60709"
        severity    = "critical"

    strings:
        $evil_file  = "evil.blf" ascii wide
        $groom_file = "groom_" ascii wide
        $etw_func   = "EtwEventWrite" ascii wide
        $amsi_func  = "AmsiScanBuffer" ascii wide
        $magic      = { 37 13 37 13 }
        $token_off  = { C0 04 00 00 }

    condition:
        3 of them
}

IOCs — System Artifacts

Behavioral Detection

FILE:    Mass creation of *.blf in C:\Windows\Temp\ (> 100 in seconds)
FILE:    Creation of C:\Windows\Temp\evil.blf
PROCESS: REALTIME_PRIORITY process + ClfsReadRestartArea calls
MEMORY:  Write to PAGE_EXECUTE_READWRITE + immediate CreateThread
API:     VirtualProtect over EtwEventWrite or AmsiScanBuffer
KERNEL:  PsInitialSystemProcess access from user-mode

Quick Verification

# Check grooming files
Get-ChildItem C:\Windows\Temp -Filter "groom_*.blf" | Measure-Object

# Check exploit file
Test-Path C:\Windows\Temp\evil.blf

📚 Referencias Técnicas / Technical References

⚠️ Legal Notice / Aviso Legal

EN: This exploit PoC is published for security research, vulnerability analysis, threat intelligence, and defensive purposes ONLY. Using this code against systems without explicit written authorization is illegal and may violate the CFAA, Computer Misuse Act, and equivalent laws. Authors assume no liability for misuse.

ES: Este PoC de exploit se publica únicamente para investigación de seguridad, análisis de vulnerabilidades, inteligencia de amenazas y fines defensivos. Usar este código contra sistemas sin autorización escrita explícita es ilegal y puede violar el CFAA, Computer Misuse Act y legislación equivalente. Los autores no asumen responsabilidad por el uso indebido.

CVE ID	CVE-2025-60709
Tipo	Local Privilege Escalation (LPE)
Componente	CLFS.sys (Common Log File System driver)
Sistema objetivo	Windows 11 24H2 (build 26100.3485+)
Arquitectura	x64 únicamente
Vector	Buffer overflow en parsing de contenedor CLFS
Impacto	Escalación a NT AUTHORITY\SYSTEM
Prerequisitos	Ejecución local de código (usuario estándar)

`EPROCESS_TOKEN`	`0x4C0`	Token de seguridad del proceso
`EPROCESS_PID`	`0x440`	Process ID (PID)
`EPROCESS_LINKS`	`0x448`	Lista enlazada de procesos activos
`EPROCESS_NAME`	`0x5A8`	Nombre del proceso (ImageFileName)

`GetKernelBase()`	`ZwQuerySystemInformation(SystemModuleInformation)` → base de ntoskrnl.exe
`KillETW()`	VirtualProtect + sobreescribe `EtwEventWrite` en ntdll.dll con `0xC3` (RET)
`KillAMSI()`	Carga amsi.dll + sobreescribe `AmsiScanBuffer` con `0xC3` (RET)
`GroomLookaside()`	Crea 4096 logs CLFS para exhaust de lookaside lists → heap determinista
`ClfsArbWrite()`	Núcleo del exploit — primitiva de escritura arbitraria en kernel
`main()`	Orquesta ataque: ETW→AMSI→groom→token theft→arb write→beacon

Tipo	Exploit funcional (según documentación)	Demo educativa únicamente
APIs	Acceso directo (ntdll, clfsw32, advapi32)	`syscall.NewLazyDLL()` wrappers
Checksum CLFS	Algoritmo completo	Placeholder simplificado
Direcciones kernel	Reales	Hardcoded placeholder (`0x123456`)
Payload C2	Shellcode 1789 bytes	Bytes NOP (`0x90`) de prueba
Resultado esperado	Escalación a SYSTEM	Mensaje `"Arb write failed (yeah)"`

HVCI (Hypervisor-protected Code Integrity)	Alta — previene escritura en memoria kernel
kCFI (Kernel Control Flow Integrity)	Alta — dificulta ROP/JOP chains
CFG (Control Flow Guard)	Media — dificulta ejecución de shellcode
Windows Defender	Media — detecta técnicas conocidas
Actualización Windows	Alta — parche oficial elimina la vulnerabilidad

Archivo malformado	`C:\Windows\Temp\evil.blf`
Log malformado	`\\.\C:\Windows\Temp\evil_log`
Archivos grooming	`C:\Windows\Temp\groom_00000.blf` … `groom_04095.blf`
Proceso	Alta prioridad (`REALTIME_PRIORITY_CLASS`) anómala

CVE ID	CVE-2025-60709
Type	Local Privilege Escalation (LPE)
Component	CLFS.sys (Common Log File System driver)
Target OS	Windows 11 24H2 (build 26100.3485+)
Architecture	x64 only
Vector	Buffer overflow in CLFS container parsing
Impact	Escalation to NT AUTHORITY\SYSTEM
Prerequisites	Local code execution (standard user)

`EPROCESS_TOKEN`	`0x4C0`	Process security token
`EPROCESS_PID`	`0x440`	Process ID
`EPROCESS_LINKS`	`0x448`	Active process linked list
`EPROCESS_NAME`	`0x5A8`	Process name (ImageFileName)

Type	Functional exploit (per docs)	Educational demo only
APIs	Direct (ntdll, clfsw32, advapi32)	`syscall.NewLazyDLL()` wrappers
CLFS checksum	Full algorithm	Simplified placeholder
Kernel addresses	Real	Hardcoded placeholder (`0x123456`)
C2 payload	1789-byte shellcode	NOP bytes (`0x90`)
Expected result	SYSTEM escalation	Message `"Arb write failed (yeah)"`

HVCI (Hypervisor-protected Code Integrity)	High — prevents kernel memory writes
kCFI (Kernel Control Flow Integrity)	High — blocks ROP/JOP chains
CFG (Control Flow Guard)	Medium — hinders shellcode execution
Windows Defender	Medium — detects known techniques
Windows Update	High — official patch eliminates the vulnerability

Malformed file	`C:\Windows\Temp\evil.blf`
Malformed log	`\\.\C:\Windows\Temp\evil_log`
Grooming files	`C:\Windows\Temp\groom_00000.blf` … `groom_04095.blf`
Process	Anomalous `REALTIME_PRIORITY_CLASS` priority

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CVE-2025-60709