Peetch – An eBPF Playground
peetch is a collection of tools aimed at experimenting with different aspects of eBPF to bypass TLS protocol protections.
Currently, peetch includes two subcommands. The first called dump aims to sniff network traffic by associating information about the source process with each packet. The second called tls allows to identify processes using OpenSSL to extract cryptographic keys.
Combined, these two commands make it possible to decrypt TLS exchanges recorded in the PCAPng format.
Installation
peetch relies on several dependencies including non-merged modifications of bcc and Scapy. A Docker image can be easily built in order to easily test peetch using the following command:
docker build -t quarkslab/peetch .
Commands Walk Through
The following examples assume that you used the following command to enter the Docker image and launch examples within it:
docker run --privileged --network host --mount type=bind,source=/sys,target=/sys --mount type=bind,source=/proc,target=/proc --rm -it quarkslab/peetch
dump
This sub-command gives you the ability to sniff packets using an eBPF TC classifier and to retrieve the corresponding PID and process names with:
peetch dump
curl/1289291 - Ether / IP / TCP 10.211.55.10:53052 > 208.97.177.124:https S / Padding
curl/1289291 - Ether / IP / TCP 208.97.177.124:https > 10.211.55.10:53052 SA / Padding
curl/1289291 - Ether / IP / TCP 10.211.55.10:53052 > 208.97.177.124:https A / Padding
curl/1289291 - Ether / IP / TCP 10.211.55.10:53052 > 208.97.177.124:https PA / Raw / Padding
curl/1289291 - Ether / IP / TCP 208.97.177.124:https > 10.211.55.10:53052 A / Padding
Note that for demonstration purposes, dump will only capture IPv4 based TCP segments.
For convenience, the captured packets can be store to PCAPng along with process information using --write:
peetch dump --write peetch.pcapng
^C
This PCAPng can easily be manipulated with Wireshark or Scapy:
scapy
>>> l = rdpcap("peetch.pcapng")
>>> l[0]
<Ether dst=00:1c:42:00:00:18 src=00:1c:42:54:f3:34 type=IPv4 |<IP version=4 ihl=5 tos=0x0 len=60 id=11088 flags=DF frag=0 ttl=64 proto=tcp chksum=0x4bb1 src=10.211.55.10 dst=208.97.177.124 |<TCP sport=53054 dport=https seq=631406526 ack=0 dataofs=10 reserved=0 flags=S window=64240 chksum=0xc3e9 urgptr=0 options=[('MSS', 1460), ('SAckOK', b''), ('Timestamp', (1272423534, 0)), ('NOP', None), ('WScale', 7)] |<Padding load='x00x00' |>>>>
>>> l[0].comment
b'curl/1289909'
tls
This sub-command aims at identifying process that uses OpenSSl and makes it is to dump several things like plaintext and secrets.
By default, peetch tls will only display one line per process, the --directions argument makes it possible to display the exchanges messages:
peetch tls --directions
<- curl (1291078) 208.97.177.124/443 TLS1.2 ECDHE-RSA-AES128-GCM-SHA256
> curl (1291078) 208.97.177.124/443 TLS1.-1 ECDHE-RSA-AES128-GCM-SHA256
Displaying OpenSSL buffer content is achieved with --content.
peetch tls --content
<- curl (1290608) 208.97.177.124/443 TLS1.2 ECDHE-RSA-AES128-GCM-SHA256
0000 47 45 54 20 2F 20 48 54 54 50 2F 31 2E 31 0D 0A GET / HTTP/1.1..
0010 48 6F 73 74 3A 20 77 77 77 2E 70 65 72 64 75 2E Host: www.perdu.
0020 63 6F 6D 0D 0A 55 73 65 72 2D 41 67 65 6E 74 3A com..User-Agent:
0030 20 63 75 72 6C 2F 37 2E 36 38 2E 30 0D 0A 41 63 curl/7.68.0..Ac
-> curl (1290608) 208.97.177.124/443 TLS1.-1 ECDHE-RSA-AES128-GCM-SHA256
0000 48 54 54 50 2F 31 2E 31 20 32 30 30 20 4F 4B 0D HTTP/1.1 200 OK.
0010 0A 44 61 74 65 3A 20 54 68 75 2C 20 31 39 20 4D .Date: Thu, 19 M
0020 61 79 20 32 30 32 32 20 31 38 3A 31 36 3A 30 31 ay 2022 18:16:01
0030 20 47 4D 54 0D 0A 53 65 72 76 65 72 3A 20 41 70 GMT..Server: Ap
The --secrets arguments will display TLS Master Secrets extracted from memory. The following example leverages --write to write master secrets to discuss to simplify decruypting TLS messages with Scapy:
$ (sleep 5; curl https://www.perdu.com/?name=highly%20secret%20information --tls-max 1.2 -http1.1) &
# peetch tls --write &
curl (1293232) 208.97.177.124/443 TLS1.2 ECDHE-RSA-AES128-GCM-SHA256
# peetch dump --write traffic.pcapng
^C
# Add the master secret to a PCAPng file
$ editcap --inject-secrets tls,1293232-master_secret.log traffic.pcapng traffic-ms.pcapng
$ scapy
>>> load_layer("tls")
>>> conf.tls_session_enable = True
>>> l = rdpcap("traffic-ms.pcapng")
>>> l[13][TLS].msg
[<TLSApplicationData data='GET /?name=highly%20secret%20information HTTP/1.1rnHost: www.perdu.comrnUser-Agent: curl/7.68.0rnAccept: */*rnrn' |>]
Limitations
By design, peetch only supports OpenSSL and TLS 1.2.
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