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Process lifecycle

Tetragon observes by default the process lifecycle via exec and exit

Tetragon observes process creation and termination with default configuration and generates process_exec and process_exit events:

  • The process_exec events include useful information about the execution of binaries and related process information. This includes the binary image that was executed, command-line arguments, the UID context the process was executed with, the process parent information, the capabilities that a process had while executed, the process start time, the Kubernetes Pod, labels and more.
  • The process_exit events, as the process_exec event shows how and when a process started, indicate how and when a process is removed. The information in the event includes the binary image that was executed, command-line arguments, the UID context the process was executed with, process parent information, process start time, the status codes and signals on process exit. Understanding why a process exited and with what status code helps understand the specifics of that exit.

Both these events include Linux-level metadata (UID, parents, capabilities, start time, etc.) but also Kubernetes-level metadata (Kubernetes namespace, labels, name, etc.). This data make the connection between node-level concepts, the processes, and Kubernetes or container environments.

These events enable a full lifecycle view into a process that can aid an incident investigation, for example, we can determine if a suspicious process is still running in a particular environment. For concrete examples of such events, see the next use case on process execution.

1 - Process execution

Monitor process lifecycle with process_exec and process_exit

This first use case is monitoring process execution, which can be observed with the Tetragon process_exec and process_exit JSON events. These events contain the full lifecycle of processes, from fork/exec to exit, including metadata such as:

  • Binary name: Defines the name of an executable file
  • Parent process: Helps to identify process execution anomalies (e.g., if a nodejs app forks a shell, this is suspicious)
  • Command-line argument: Defines the program runtime behavior
  • Current working directory: Helps to identify hidden malware execution from a temporary folder, which is a common pattern used in malwares
  • Kubernetes metadata: Contains pods, labels, and Kubernetes namespaces, which are critical to identify service owners, particularly in a multitenant environments
  • exec_id: A unique process identifier that correlates all recorded activity of a process

As a first step, let’s start monitoring the events from the xwing pod:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents -o compact --namespace default --pod xwing

Then in another terminal, let’s kubectl exec into the xwing pod and execute some example commands:

kubectl exec -it xwing -- /bin/bash
whoami

If you observe, the output in the first terminal should be:

🚀 process default/xwing /bin/bash
🚀 process default/xwing /usr/bin/whoami
💥 exit    default/xwing /usr/bin/whoami 0

Here you can see the binary names along with its arguments, the pod info, and return codes in a compact one-line view of the events.

For more details use the raw JSON events to get detailed information, you can stop the Tetragon CLI by Crl-C and parse the tetragon.log file by executing:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | jq 'select(.process_exec.process.pod.name=="xwing" or .process_exit.process.pod.name=="xwing")'

Example process_exec and process_exit events can be:

Process Exec Event

{
  "process_exec": {
    "process": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjExNDI4NjE1NjM2OTAxOjUxNTgz",
      "pid": 51583,
      "uid": 0,
      "cwd": "/",
      "binary": "/usr/bin/whoami",
      "arguments": "--version",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:54:45.615Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 50
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "refcnt": 1
    },
    "parent": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "pid": 43872,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:15:36.225Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 43
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkxODU5NTMzOTk6NDM4NjE=",
      "refcnt": 1
    }
  },
  "node_name": "kind-control-plane",
  "time": "2022-05-11T12:54:45.615Z"
}

Process Exit Event

{
  "process_exit": {
    "process": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjExNDI4NjE1NjM2OTAxOjUxNTgz",
      "pid": 51583,
      "uid": 0,
      "cwd": "/",
      "binary": "/usr/bin/whoami",
      "arguments": "--version",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:54:45.615Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 50
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI="
    },
    "parent": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "pid": 43872,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:15:36.225Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 43
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkxODU5NTMzOTk6NDM4NjE="
    }
  },
  "node_name": "kind-control-plane",
  "time": "2022-05-11T12:54:45.616Z"
}

2 - Advanced Process execution

Advanced Process Execution monitoring using Tracing Policies

Monitor ELF or Flat binaries execution

Advanced process execution can be performed by using Tracing Policies to monitor the execve system call path.

If we want to monitor execution of Executable and Linkable Format (ELF) or flat binaries before they are actually executed. Then the process-exec-elf-begin tracing policy is a good first choice.

Before going forward, verify that all pods are up and running, ensure you deploy our Demo Application to explore the Security Observability Events:

kubectl create -f https://raw.githubusercontent.com/cilium/cilium/v1.15.3/examples/minikube/http-sw-app.yaml

It might take several seconds for some pods until they satisfy all the dependencies:

kubectl get pods -A

The output should be similar to:

NAMESPACE            NAME                                         READY   STATUS    RESTARTS   AGE
default              deathstar-54bb8475cc-6c6lc                   1/1     Running   0          2m54s
default              deathstar-54bb8475cc-zmfkr                   1/1     Running   0          2m54s
default              tiefighter                                   1/1     Running   0          2m54s
default              xwing                                        1/1     Running   0          2m54s
kube-system          tetragon-sdwv6                               2/2     Running   0          27m

Let’s apply the process-exec-elf-begin Tracing Policy.

kubectl apply -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/process-exec/process-exec-elf-begin.yaml

Then start monitoring events with the tetra CLI:

kubectl exec -it -n kube-system ds/tetragon -c tetragon -- tetra getevents

In another terminal, kubectl exec into the xwing Pod:

kubectl exec -it xwing -- /bin/bash

And execute some commands:

id

The tetra CLI will generate the following ProcessKprobe events:

{
  "process_kprobe": {
    "process": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjE2NjY0MDI4MTA4MzcxOjM2NDk5",
      "pid": 36499,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve",
      "start_time": "2023-08-02T11:58:53.618461573Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://775beeb1a25a95e10dc149d6eb166bf45dd5e6039e8af3b64e8fb4d29669f349",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2023-08-02T07:24:54Z",
          "pid": 13
        },
        "pod_labels": {
          "app.kubernetes.io/name": "xwing",
          "class": "xwing",
          "org": "alliance"
        }
      },
      "docker": "775beeb1a25a95e10dc149d6eb166bf",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjE2NjYyNzg3ODI1MTQ4OjM2NDkz",
      "refcnt": 1,
      "tid": 36499
    },
      "parent": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjE2NjYyNzg3ODI1MTQ4OjM2NDkz",
      "pid": 36493,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve rootcwd clone",
      "start_time": "2023-08-02T11:58:52.378178852Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://775beeb1a25a95e10dc149d6eb166bf45dd5e6039e8af3b64e8fb4d29669f349",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2023-08-02T07:24:54Z",
          "pid": 13
        },
        "pod_labels": {
          "app.kubernetes.io/name": "xwing",
          "class": "xwing",
          "org": "alliance"
        }
      },
      "docker": "775beeb1a25a95e10dc149d6eb166bf",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjE2NjYyNzE2OTU0MjgzOjM2NDg0",
      "tid": 36493
    },
    "function_name": "security_bprm_creds_from_file",
    "args": [
      {
        "file_arg": {
          "path": "/bin/busybox"
        }
      }
    ],
    "action": "KPROBE_ACTION_POST"
  },
  "node_name": "kind-control-plane",
  "time": "2023-08-02T11:58:53.624096751Z"
}

In addition to the Kubernetes Identity and process metadata, ProcessKprobe events contain the binary being executed. In the above case they are:

  • function_name: where we are hooking into the kernel to read the binary that is being executed.
  • file_arg: that includes the path being executed, and here it is /bin/busybox that is the real binary being executed, since on the xwing pod the container is running busybox. The binary /usr/bin/id -> /bin/busybox points to busybox.

To disable the process-exec-elf-being Tracing Policy run:

kubectl delete -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/process-exec/process-exec-elf-begin.yaml

3 - Privileged execution

Monitor process capabilities and kernel namespace access

Tetragon also provides the ability to check process capabilities and kernel namespaces access.

This information would help us determine which process or Kubernetes pod has started or gained access to privileges or host namespaces that it should not have. This would help us answer questions like:

Which Kubernetes pods are running with CAP_SYS_ADMIN in my cluster?

Which Kubernetes pods have host network or pid namespace access in my cluster?

Step 1: Enabling Process Credential and Namespace Monitoring

  • Edit the Tetragon configmap:

    kubectl edit cm -n kube-system tetragon-config

  • Set the following flags from “false” to “true”:

    # enable-process-cred: true
# enable-process-ns: true

  • Save your changes and exit.

  • Restart the Tetragon daemonset:

    kubectl rollout restart -n kube-system ds/tetragon

Step 2: Deploying a Privileged Nginx Pod

  • Create a YAML file (e.g., privileged-nginx.yaml) with the following PodSpec:

    apiVersion: v1
kind: Pod
metadata:
  name: privileged-the-pod
spec:
  hostPID: true
  hostNetwork: true
  containers:
  - name: privileged-the-pod
    image: nginx:latest
    ports:
    - containerPort: 80
    securityContext:
      privileged: true

  • Apply the configuration:

    kubectl apply -f privileged-nginx.yaml

Step 3: Monitoring with Tetragon

  • Start monitoring events from the privileged Nginx pod:

    kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents --namespace default --pod privileged-the-pod

  • You should observe Tetragon generating events similar to these, indicating the privileged container start:

    🚀 process default/privileged-nginx /nginx -g daemon off;  🛑 CAP_SYS_ADMIN