sslsnoop dumps live session keys from openssh and can also decrypt the traffic on the fly.
- Works if scapy doesn’t drop packets. using pcap instead of SOCK_RAW helps a lot now.
- Works better on interactive traffic with no traffic at the time of the ptrace. It follows the flow, after that.
- Dumps one file by fd in outputs/
- Attaching a process is quickier with –addr 0xb788aa98 as provided by haystack INFO:abouchet:found instance @ 0xb788aa98
- how to get a pickled session_state file : $ sudo haystack –pid `pgrep ssh` sslsnoop.ctypes_openssh.session_state search > ss.pickled
Not all ciphers are implemented.
Workings ciphers: aes128-ctr, aes192-ctr, aes256-ctr, blowfish-cbc, cast128-cbc
Partially workings ciphers (INBOUND only ?!): aes128-cbc, aes192-cbc, aes256-cbc
Non workings ciphers: 3des-cbc, 3des, ssh1-blowfish, arcfour, arcfour1280
It can also dump DSA and RSA keys from ssh-agent or sshd ( or others ).
You can download sslsnoop here:
trolldbois-sslsnoop.zip
HOWTO:
------
$ sudo easy_install sslsnoop
$ mkdir outputs
You really have to. Please.
$ sudo sslsnoop # try ssh, sshd and ssh-agent... for various things
$ sudo sslsnoop-openssh live `pgrep ssh` # dumps SSH decrypted traffic in outputs/
$ sudo sslsnoop-openssh offline --help # dumps SSH decrypted traffic in outputs/ from a pcap file
$ sudo sslsnoop-openssl `pgrep ssh-agent` # dumps RSA and DSA keys
and go and check outputs/.
hints :
-------
a) works if scapy doesn't drop packets. using pcap instead of SOCK_RAW helps a lot now.
b) works better on interactive traffic with no traffic at the time of the ptrace. It follows the flow, after that.
c) Dumps one file by fd in outputs/
d) Attaching a process is quickier with --addr 0xb788aa98 as provided by haystack
INFO:abouchet:found instance <class 'ctypes_openssh.session_state'> @ 0xb788aa98
e) how to get a pickled session_state file :
$ sudo haystack --pid `pgrep ssh` sslsnoop.ctypes_openssh.session_state search > ss.pickled
not so FAQ :
============
What does it do, really ?:
--------------------------
It dumps live session keys from an openssh , and decrypts the traffic on the fly.
Not all ciphers are implemented.
Workings ciphers : aes128-ctr, aes192-ctr, aes256-ctr, blowfish-cbc, cast128-cbc
Partially workings ciphers (INBOUND only ?!): aes128-cbc, aes192-cbc, aes256-cbc
Non workings ciphers : 3des-cbc, 3des, ssh1-blowfish, arcfour, arcfour1280
It can also dump DSA and RSA keys from ssh-agent or sshd ( or others ).
How do it knows that the structures is valid ? :
------------------------------------------------
You add some constraints ( expectedValues ) on the fields. Pointers are also a good start.
Yeah, but you have to be root, so what's the use ? :
----------------------------------------------------
Monitoring ssh traffic on honeypots ?
Monitoring encrypted traffic on honeypots ?
Monitoring encrypted traffic on ... somewhere your are root ?
It does not work on my openssh ? :
-----------------------------------
tested on OpenSSH 5.5.
Should work on most recent version.. I didn't check for structure modification. but that would explain a lot.
It work really good on intereactive session with no traffic at the time of execution. (clean cipher state in memory)
It can work on a busy ssh stream, *IF* a) the cipher state is clean, b) scapy doesn't loose packets (CPU ?).
-> yeah the GIL really sucks
How can i decrypt a pcap file ? :
----------------------------------
Use the offline mode.
Where does the idea comes from ? :
-----------------------------------
use http://www.hsc.fr/ressources/breves/passe-partout.html.fr to get keys
use http://pauldotcom.com/2010/10/tsharkwireshark-ssl-decryption.html
or http://www.rtfm.com/ssldump/ to read streams
use scapy, because it's fun ? but we need IP reassembly .
pynids could be more useful...
dsniff is now in python ?
flowgrep
use python.
What are the dependencies ? :
----------------------------
python-haystack (same author)
python-ptrace
scapy
python-pcap / python-xxxpcap ( recommended for perf issues )
paramiko (for ssh decryption) [ TODO, extract & kill dep. we only need Message and Packetizer ]
python-psutil
Conclusion :
------------
poc done.
Next, `pgrep firefox`.
Biblio
-------
Bringing volatility to Linux
http://dfsforensics.blogspot.com/2011/03/bringing-linux-support-to-volatility.html
Extracting truecrypt keys from memory
http://jessekornblum.com/tools/volatility/cryptoscan.py
python-ptrace ( hey, haypo again)
https://bitbucket.org/haypo/python-ptrace/wiki/Home
https://bitbucket.org/haypo/python-ptrace/wiki/Documentation
from ptrace.debugger.memory_mapping import readProcessMappings
openssl.py is passe-partout.py - OK - 04/03/2011
OpenSSH, testing ciphers
========================
Ciphers
Specifies the ciphers allowed for protocol version 2 in order of preference. Multiple ciphers must be comma-separated. The supported ciphers
are “3des-cbc”, “aes128-cbc”, “aes192-cbc”, “aes256-cbc”, “aes128-ctr”, “aes192-ctr”, “aes256-ctr”, “arcfour128”, “arcfour256”, “arcfour”,
“blowfish-cbc”, and “cast128-cbc”. The default is:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
aes256-cbc,arcfour
force one :
ssh -c aes192-ctr log@host
firefox & NSS
=============
INFO:abouchet:found instance <class 'ctypes_nss_generated.CERTCertificateStr'> @ 0xbfe12c20 => sur la stack
INFO:abouchet:Looking at 0x85f00000-0x86000000 (rw-p)
INFO:abouchet:processed 6465536 bytes
ptrace.debugger.process_error.ProcessError: readBytes(0x84d28ae4, 392) error: [Errno 5] Input/output error
## weird ....
4894720
Architecture
============
openssh creates a OpenSSHLiveDecryptatator which inherits a OpenSSHKeysFinder
OpenSSHLiveDecryptatator :
* connects to/launch a network.Sniffer. (scapy)
* OpenSSHKeysFinder calls haystack to fetch the session_state
- memory capture/ptrace is done in a subprocess
- target process is not under ptrace anymore when openssh runs.
- keys are acquired
* SessionCiphers are created from pickled values from haystack
- one for inbound traffic
- one for outbound traffic
* each SessionCipher is coupled with :
- a socket given by a TCPStream ( Inbound and Outbound TCPstate)
- a paramiko Packetizer which is a ssh protocol handler.
* a cipher engine is used by the paramiko.Packetizer to decrypt data from the TCPStream socket
* the Packetizer uses :
- the socket to read it's data from the 'network'.
- the cipher to decrypt the data
* a SSHStreamToFile is created for each stream and is given the packetizer and the overall context ( cipher, socket )
- the SSHStreamToFile try to process the packetizer's outputs into a file.
* a Supervisor is created to handle traffic ( select on socket )
- both SSHStreamToFile are given to the Supervisor with their respective socket
TODO:
SSHStream uses the packets is orderedQueue and the cipher, to try to find a SSH packet
- algo 1 : copy original cipher state, decrypt first block of packet [0],
if not valid, drop packet and loop to next one (for x packets)
if valid, switch to go-trough mode and queue current + all packets data to socket
- algo 2 : try to find a valid packet, block per block/long by long
if valid, switch to go-trough mode and queue current + all packets data to socket
Or read more
here.
