Enhanced Session Recording with BPF

Teleport's default SSH and Kubernetes session recording feature captures what is echoed to a terminal.

This has inherent advantages, for example, because no input is captured, Teleport session recordings typically do not contain passwords that were entered into a terminal.

The disadvantage is that session recordings can be bypassed using several techniques:

• Obfuscation. For example, even though the command echo Y3VybCBodHRwOi8vd3d3LmV4YW1wbGUuY29tCg== | base64 --decode | sh does not contain curl http://www.example.com, when decoded, that is what is run.
• Shell scripts. For example, if a user uploads and executes a script, the commands run within the script are not captured, simply the output.
• Terminal controls. Terminals support a wide variety of controls including the ability for users to disable terminal echo. This is frequently used when requesting credentials. Disabling terminal echo allows commands to be run without being captured.

Furthermore, due to their unstructured nature, session recordings are difficult to ingest and perform monitoring/alerting on.

Teleport Enhanced Session Recording mitigates all three concerns by providing advanced security, greater logging capabilities, and better correlates a user with their activities.

Prerequisites

Teleport 7.0+ with Enhanced Session Recording requires Linux kernel 5.8 (or above).

You can check your kernel version using the uname command. The output should look something like the following.

uname -r
5.8.17

Linux distributions and supported kernels

Step 1/3. Install and configure Teleport node

Follow our installation instructions to install Teleport Auth, Proxy and Nodes.

Set up the Teleport node with this etc/teleport.yaml. See our configuration file setup for more instructions.

# Example config to be saved as etc/teleport.yaml
teleport:
  nodename: graviton-node
  auth_token: exampletoken
  auth_servers:
  # Replace with IP of Teleport Auth server.
  - 127.0.0.1:3025
  data_dir: /var/lib/teleport
proxy_service:
  enabled: false
auth_service:
  enabled: false
ssh_service:
  enabled: true
  enhanced_recording:
    # Enable or disable enhanced auditing for this node. Default value: false.
    enabled: true

    # Optional: command_buffer_size is optional with a default value of 8 pages.
    command_buffer_size: 8

    # Optional: disk_buffer_size is optional with default value of 128 pages.
    disk_buffer_size: 128

    # Optional: network_buffer_size is optional with default value of 8 pages.
    network_buffer_size: 8

    # Optional: Controls where cgroupv2 hierarchy is mounted. Default value:
    # /cgroup2.
    cgroup_path: /cgroup2

Step 2/3. Test by logging into node via Teleport

Session with Enhanced Session Recording will be marked as 'true' in the logs.

{
  "code": "T2004I",
  "ei": 23,
  "enhanced_recording": true,
  "event": "session.end",
  "interactive": true,
  "namespace": "default",
  "participants": [
    "benarent"
  ],
  "server_id": "585fc225-5cf9-4e9f-8ff6-1b0fd6885b09",
  "sid": "ca82b98d-1d30-11ea-8244-cafde5327a6c",
  "time": "2019-12-12T22:44:46.218Z",
  "uid": "83e67464-a93a-4c7c-8ce6-5a3d8802c3b2",
  "user": "benarent"
}

Step 3/3. Inspect logs

The resulting enhanced session recording will be shown in Teleport's Audit Log.

teleport-auth ~:  tree /var/lib/teleport/log
/var/lib/teleport/log
├── 1048a649-8f3f-4431-9529-0c53339b65a5
│   ├── 2020-01-13.00:00:00.log
│   └── sessions
│       └── default
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.chunks.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.events.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.session.command-events.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.session.network-events.gz
│           └── fad07202-35bb-11ea-83aa-125400432324.index
├── events.log -> /var/lib/teleport/log/1048a649-8f3f-4431-9529-0c53339b65a5/2020-01-13.00:00:00.log
├── playbacks
│   └── sessions
│       └── default
└── upload
└── sessions
└── default

To quickly check the status of the audit log, you can simply tail the logs with tail -f /var/lib/teleport/log/events.log, the resulting capture from Teleport will be a JSON log for each command and network request.

{"argv":["google.com"],"cgroup_id":4294968064,"code":"T4000I","ei":5,"event":"session.command","login":"root","namespace":"default","path":"/bin/ping","pid":2653,"ppid":2660,"program":"ping","return_code":0,"server_id":"96f2bed2-ebd1-494a-945c-2fd57de41644","sid":"44c6cea8-362f-11ea-83aa-125400432324","time":"2020-01-13T18:05:53.919Z","uid":"734930bb-00e6-4ee6-8798-37f1e9473fac","user":"benarent"}