使用 Sysdig Falco 和 Kubernetes 设置运行时容器安全监控

Falco 是一个云原生运行时安全系统，可与容器和原始 Linux 主机一起使用。它由 Sysdig 开发，是 Cloud Native Computing Foundation（云原生计算基金会）的一个沙箱项目。Falco 的工作方式是查看文件更改、网络活动、进程表和其他数据是否存在可疑行为，然后通过可插拔后端发送警报。通过内核模块或扩展的 BPF 探测器在主机的系统调用级别检查事件。Falco 包含一组丰富的规则，您可以编辑这些规则以标记特定的异常行为，并为正常的计算机操作创建允许列表。

在本教程中，您将学习如何在 IBM Cloud 上的 Kubernetes 集群上安装和设置 Falco、如何创建合成安全事件以及如何在 Falco 中查看事件。最后，将 Falco 连接起来，在运行时向 Slack 发送安全警报。本教程适用于标准 Kubernetes 和 Red Hat OpenShift on IBM Cloud。

您需要获取此处的源代码：

git clone https://gitlab.com/nibalizer/falco-iks
cd falco-iks

使用 Kubernetes daemonset配置 Falco

由于 Kubernetes 1.12 环境，本教程使用 k8s-with-rbac 文件。Falco 需要设置几个文件：用于运行 Falco daemonset 的 Kubernetes 配置与针对 daemonset 本身的配置的组合。

1：查看 Falco 文件

 Falco 使用 Kubernetes 中的服务帐户来访问 Kubernetes API。falco-account.yaml 规范设置了一种基于角色的通用访问控制三重方法：ServiceAccount、ClusterRole 和 ClusterRoleBinding。ClusterRole 包含关于所授予的访问权限的信息。如果您在这些文件中没有进行任何更改，那么 Falco 守护进程只能读取和列示，而不能修改 Kubernetes API 中的任何对象。

$ ls -l
total 20
-rw-r--r-- 1 nibz nibz  931 Mar 29 15:46 falco-account.yaml
drwxr-xr-x 2 nibz nibz 4096 Mar 29 15:51 falco-config/
-rw-r--r-- 1 nibz nibz 2138 Mar 29 15:48 falco-daemonset-configmap.yaml
-rw-r--r-- 1 nibz nibz  196 Mar 29 15:45 falco-service.yaml
-rw-r--r-- 1 nibz nibz   13 Mar 29 15:27 Readme.md

2 ：配置基于角色的访问控制 (RBAC)

kubectl apply -f falco-account.yaml
serviceaccount/falco-account created
clusterrole.rbac.authorization.k8s.io/falco-cluster-role created
clusterrolebinding.rbac.authorization.k8s.io/falco-cluster-role-binding created

3：应用 Falco 服务对象

$ kubectl apply -f falco-service.yaml
service/falco-service created

4：创建 falco-config ConfigMap

Falco 的配置被分成几个文件。falco.yaml 是指守护进程配置的细节：输出类型、端口等。其他 *_rules.yaml 文件包含 Falco 会针对其进行触发的检查（正在打开的 shell、正在修改的文件等）。通过将 --from-file 自变量与目录一起使用，将所有这些文件组合到单个 ConfigMap 中： 

 kubectl create configmap falco-config --from-file=falco-config
configmap/falco-config created

5：启动 Falco DaemonSet

 最后，运行 Falco 应用程序。它作为 DaemonSet 运行，使您可以在每个节点上运行一个：

kubectl apply -f falco-daemonset-configmap.yaml
daemonset.extensions/falco-daemonset created

 

6：检查 pod 是否正确启动

kubectl get pod
NAME                    READY   STATUS    RESTARTS   AGE
falco-daemonset-99p8j   1/1     Running   0          26s
falco-daemonset-wf2lf   1/1     Running   0          26s
falco-daemonset-wqrwm   1/1     Running   0          26s

7：检查日志并读取 DKMS 消息

kubectl logs falco-daemonset-wf2lf
* Setting up /usr/src links from host
* Unloading falco-probe, if present
* Running dkms install for falco

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area...
make -j2 KERNELRELEASE=4.4.0-148-generic -C /lib/modules/4.4.0-148-generic/build M=/var/lib/dkms/falco/0.1.2780dev/build....
cleaning build area...

DKMS: build completed.

falco-probe.ko:

Falco 正在运行并且正在记录事件。

查看 Falco 的配置

1：检查 DaemonSet 配置

 运行以下命令，以告知 DaemonSet 使用您先前设置的服务帐户和权限来运行：

cat falco-daemonset-configmap.yaml | grep serviceAcc
serviceAccount: falco-account

查看 falco-account.yaml 以获取详细信息。此配置提供对 Kubernetes API 服务器中几乎所有内容的读取访问权限。

您将许多重要的目录从 Kubernetes 主机安装到 Falco pod 中：

cat falco-daemonset-configmap.yaml | grep -A 11 volumes:
      volumes:
        - name: containerd-socket
          hostPath:
            path: /run/containerd/containerd.sock
        - name: dev-fs
          hostPath:
            path: /dev
        - name: proc-fs
          hostPath:
            path: /proc
        - name: boot-fs
          hostPath:

此步骤使 Falco 可以与容器运行时环境进行交互，以提取容器元数据（例如，容器名称和底层镜像名称），查询主机的进程表以发现进程名称。另需注意，此示例将映射 containerd-socket，而不是 docker-socket。

2 ：检查 Falco 配置文件

ls falco-config/
falco_rules.local.yaml  falco_rules.yaml  falco.yaml  k8s_audit_rules.yaml

3：查看 Falco 值

 该规则监视可能有害的 Netcat 命令，并在发现其处于 WARNING 级别时发出警报。

cat falco-config/falco_rules.yaml | grep -A 12 'Netcat Remote'
- rule: Netcat Remote Code Execution in Container
  desc: Netcat Program runs inside container that allows remote code execution
  condition: >
    spawned_process and container and
    ((proc.name = "nc" and (proc.args contains "-e" or proc.args contains "-c")) or
     (proc.name = "ncat" and (proc.args contains "--sh-exec" or proc.args contains "--exec"))
    )
  output: >
    Netcat runs inside container that allows remote code execution (user=%user.name
    command=%proc.cmdline container_id=%container.id container_name=%container.name image=%container.image.repository:%container.image.tag)
  priority: WARNING
  tags: [network, process]

观察 Falco 的实际应用

现在让我们看看 Falco 的实际应用。您将跟踪一个终端中的日志，然后在另一终端中综合创建一些事件，并观察事件是否记录到日志。

1：跟踪第一个终端中的日志

kubectl get pod
NAME                    READY   STATUS    RESTARTS   AGE
falco-daemonset-99p8j   1/1     Running   0          112m
falco-daemonset-wf2lf   1/1     Running   0          112m
falco-daemonset-wqrwm   1/1     Running   0          112m
$ kubectl logs -f falco-daemonset-99p8j
* Setting up /usr/src links from host
* Unloading falco-probe, if present
* Running dkms install for falco

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area...
make -j2 KERNELRELEASE=4.4.0-148-generic -C /lib/modules/4.4.0-148-generic/build M=/var/lib/dkms/falco/0.1.2780dev/build....
cleaning build area...

DKMS: build completed.

falco-probe.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/4.4.0-148-generic/kernel/extra/
mkdir: cannot create directory '/lib/modules/4.4.0-148-generic/kernel/extra': Read-only file system
cp: cannot create regular file '/lib/modules/4.4.0-148-generic/kernel/extra/falco-probe.ko': No such file or directory

depmod...

DKMS: install completed.
* Trying to load a dkms falco-probe, if present
falco-probe found and loaded in dkms
Wed May 29 14:55:36 2019: Falco initialized with configuration file /etc/falco/falco.yaml
Wed May 29 14:55:36 2019: Loading rules from file /etc/falco/falco_rules.yaml:
Wed May 29 14:55:37 2019: Loading rules from file /etc/falco/falco_rules.local.yaml:
Wed May 29 14:55:37 2019: Loading rules from file /etc/falco/k8s_audit_rules.yaml:
Wed May 29 14:55:38 2019: Starting internal webserver, listening on port 8765
{"output":"00:00:00.020155776: Informational Container with sensitive mount started (user=<NA> command=container:9d56002def78 k8s.ns=<NA> k8s.pod=<NA> container=9d56002def78 image=docker.io/falcosecurity/falco:dev mounts=/run/containerd/containerd.sock:/host/run/containerd/containerd.sock::true:private,/dev:/host/dev::true:private,/proc:/host/proc::false:private,/boot:/host/boot::false:private,/lib/modules:/host/lib/modules::false:private,/usr:/host/usr::false:private,/etc:/host/etc/::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/volumes/kubernetes.io~configmap/falco-config:/etc/falco::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/volumes/kubernetes.io~secret/falco-account-token-jlddc:/var/run/secrets/kubernetes.io/serviceaccount::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/etc-hosts:/etc/hosts::true:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/containers/falco/cb0bed6e:/dev/termination-log::true:private) k8s.ns=<NA> k8s.pod=<NA> container=9d56002def78","priority":"Informational","rule":"Launch Sensitive Mount Container","time":"1970-01-01T00:00:00.020155776Z", "output_fields": {"container.id":"9d56002def78","container.image.repository":"docker.io/falcosecurity/falco","container.image.tag":"dev","container.mounts":"/run/containerd/containerd.sock:/host/run/containerd/containerd.sock::true:private,/dev:/host/dev::true:private,/proc:/host/proc::false:private,/boot:/host/boot::false:private,/lib/modules:/host/lib/modules::false:private,/usr:/host/usr::false:private,/etc:/host/etc/::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/volumes/kubernetes.io~configmap/falco-config:/etc/falco::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/volumes/kubernetes.io~secret/falco-account-token-jlddc:/var/run/secrets/kubernetes.io/serviceaccount::false:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/etc-hosts:/etc/hosts::true:private,/var/data/kubelet/pods/c0a1a131-8221-11e9-b9cf-c68b81a15994/containers/falco/cb0bed6e:/dev/termination-log::true:private","evt.time":20155776,"k8s.ns.name":null,"k8s.pod.name":null,"proc.cmdline":"container:9d56002def78","user.name":null}}

2：在第二个终端中创建安全事件

export KUBECONFIG=/home/nibz/.bluemix/plugins/container-service/clusters/yourcluster.yml
$ kubectl get pod
NAME                    READY   STATUS    RESTARTS   AGE
falco-daemonset-99p8j   1/1     Running   0          3h2m
falco-daemonset-wf2lf   1/1     Running   0          3h2m
falco-daemonset-wqrwm   1/1     Running   0          3h2m
nibz@shockley:~/projects/falco/install-falco-iks/git-repo$ kubectl  exec -it falco-daemonset-99p8j /bin/bash
root@falco-daemonset-99p8j:/# echo "I'm in!"
I'm in!
root@falco-daemonset-99p8j:/#

在第一个终端中，您可以看到事件：

{"output":"17:58:28.064781208: Notice A shell was spawned in a container with an attached terminal (user=root k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78 shell=bash parent=<NA> cmdline=bash terminal=34816) k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78","priority":"Notice","rule":"Terminal shell in container","time":"2019-05-29T17:58:28.064781208Z", "output_fields": {"container.id":"9d56002def78","evt.time":1559152708064781208,"k8s.ns.name":"default","k8s.pod.name":"falco-daemonset-99p8j","proc.cmdline":"bash","proc.name":"bash","proc.pname":null,"proc.tty":34816,"user.name":"root"}}

3：使用 jq 处理事件

 当您使用 jq 处理事件时，Falco 会提供有关安全事件以及事件的完整 Kubernetes 上下文的有用信息，例如 pod 名称和名称空间：

echo '{"output":"17:58:28.064781208: Notice A shell was spawned in a container with an attached terminal (user=root k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78 shell=bash parent=<NA> cmdline=bash terminal=34816) k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78","priority":"Notice","rule":"Terminal shell in container","time":"2019-05-29T17:58:28.064781208Z", "output_fields": {"container.id":"9d56002def78","evt.time":1559152708064781208,"k8s.ns.name":"default","k8s.pod.name":"falco-daemonset-99p8j","proc.cmdline":"bash","proc.name":"bash","proc.pname":null,"proc.tty":34816,"user.name":"root"}}
> ' | jq '.'
{
  "output": "17:58:28.064781208: Notice A shell was spawned in a container with an attached terminal (user=root k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78 shell=bash parent=<NA> cmdline=bash terminal=34816) k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78",
  "priority": "Notice",
  "rule": "Terminal shell in container",
  "time": "2019-05-29T17:58:28.064781208Z",
  "output_fields": {
    "container.id": "9d56002def78",
    "evt.time": 1559152708064781300,
    "k8s.ns.name": "default",
    "k8s.pod.name": "falco-daemonset-99p8j",
    "proc.cmdline": "bash",
    "proc.name": "bash",
    "proc.pname": null,
    "proc.tty": 34816,
    "user.name": "root"
  }
}

现在您可以触发早前显示的 Netcat 规则：

nc -l 4444

kubectl logs falco-daemonset-99p8j
...

{"output":"18:00:41.530249297: Notice Network tool launched in container (user=root command=nc -l 4444 container_id=9d56002def78 container_name=falco image=docker.io/falcosecurity/falco:dev) k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78 k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78","priority":"Notice","rule":"Lauch Suspicious Network Tool in Container","time":"2019-05-29T18:00:41.530249297Z", "output_fields": {"container.id":"9d56002def78","container.image.repository":"docker.io/falcosecurity/falco","container.image.tag":"dev","container.name":"falco","evt.time":1559152841530249297,"k8s.ns.name":"default","k8s.pod.name":"falco-daemonset-99p8j","proc.cmdline":"nc -l 4444","user.name":"root"}}
...
$ echo '{"output":"18:00:41.530249297: Notice Network tool launched in container (user=root command=nc -l 4444 contain    er_id=9d56002def78 container_name=falco image=docker.io/falcosecurity/falco:dev) k8s.ns=default k8s.pod=falco-    daemonset-99p8j container=9d56002def78 k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78","priority":"Notice","rule":"Lauch Suspicious Network Tool in Container","time":"2019-05-29T18:00:41.530249297Z",     "output_fields": {"container.id":"9d56002def78","container.image.repository":"docker.io/falcosecurity/falco",    "container.image.tag":"dev","container.name":"falco","evt.time":1559152841530249297,"k8s.ns.name":"default","k    8s.pod.name":"falco-daemonset-99p8j","proc.cmdline":"nc -l 4444","user.name":"root"}}' | jq '.'
{
  "output": "18:00:41.530249297: Notice Network tool launched in container (user=root command=nc -l 4444 contain    er_id=9d56002def78 container_name=falco image=docker.io/falcosecurity/falco:dev) k8s.ns=default k8s.pod=falco-    daemonset-99p8j container=9d56002def78 k8s.ns=default k8s.pod=falco-daemonset-99p8j container=9d56002def78",
  "priority": "Notice",
  "rule": "Lauch Suspicious Network Tool in Container",
  "time": "2019-05-29T18:00:41.530249297Z",
  "output_fields": {
    "container.id": "9d56002def78",
    "container.image.repository": "docker.io/falcosecurity/falco",
    "container.image.tag": "dev",
    "container.name": "falco",
    "evt.time": 1559152841530249200,
    "k8s.ns.name": "default",
    "k8s.pod.name": "falco-daemonset-99p8j",
    "proc.cmdline": "nc -l 4444",
    "user.name": "root"
  }
}

您已看到 Falco 可以发现什么样的事件以及如何进行配置。

摘自

https://developer.ibm.com/zh/tutorials/installing-and-using-sysdig-falco/