CVE-2026-0421 联想ThinkPad BIOS Secure Boot绕过漏洞

// CVE-2026-0421 PoC Concept - BIOS Secure Boot Bypass // Note: This is a conceptual proof of concept for educational purposes only // Actual exploitation requires physical access and specialized firmware tools /* #include <stdio.h> #include <stdlib.h> #include <stdint.h> // Conceptual representation of Secure Boot bypass int check_secure_boot_status() { // Read Secure Boot configuration from BIOS uint32_t secure_boot_flag = read_bios_register(0x1234); // Normal check - should return 1 if Secure Boot is enabled if (secure_boot_flag & SECURE_BOOT_ENABLED) { return 1; // Secure Boot is ON } return 0; // Secure Boot is OFF } // Vulnerable implementation int vulnerable_secure_boot_check() { uint32_t sb_config = read_bios_nvram(SB_CONFIG_OFFSET); // The vulnerability exists here: // Attack can manipulate sb_config before this check // Even if BIOS shows "On", the actual check can be bypassed if (sb_config & USER_MODE_FLAG) { // Only affects User Mode - this is the vulnerable path // An attacker can modify this logic to disable SB return bypass_secure_boot(sb_config); // VULNERABLE } return SECURE_BOOT_ENFORCED; } // Mitigation: Verify Secure Boot state through multiple mechanisms void verify_secure_boot_integrity() { uint32_t primary_check = read_bios_register(PRIMARY_SB_FLAG); uint32_t secondary_check = read_uefi_variable(SB_VAR_NAME); uint32_t hardware_check = read_platform_register(HW_SB_FLAG); // All checks must be consistent if (primary_check != secondary_check || secondary_check != hardware_check) { // Inconsistency detected - potential attack trigger_security_alert(); halt_system(); } } */ # Python script to check Secure Boot status (for verification only) def check_secure_boot_status(): """ Check Secure Boot status via Windows PowerShell Note: This is for status verification, not exploitation """ import subprocess try: result = subprocess.run( ['powershell', '-Command', 'Confirm-SecureBootUEFI'], capture_output=True, text=True ) if result.returncode == 0: return "Secure Boot is ENABLED" else: return "Secure Boot is DISABLED or not supported" except Exception as e: return f"Error checking Secure Boot: {e}"