Category Archives: python

A Quick AWS Lambda Reverse Shell

Let’s say you’re doing a pentest, and you run across access to AWS Lambda. I recently learned you can get a persistent shell (for 15 minutes, at least) via Lambda, which seemed odd to me because always just considered Lambda a repeatable, but ephemeral thing.

Anyway, first create lambda_function.py with the following code. Note that you’ll need a hostname to connect to. In my case, I used pizzapower.me.

Lambda reverse shell python code.

Next, zip this up into shell.zip.

Creating shell.zip that contains our reverse shell function.

Now we are going to create a Lambda function and upload our shell.zip with the following command

aws lambda create-function --function-name test --runtime python3.9 --handler lambda_function.lambda_handler --timeout 900 --zip-file fileb://shell.zip --role <The Amazon Resource Name (ARN) of the function's execution role>
Creating our function and uploading the code.

Don’t forget to start your listener, and when you are ready, trigger the function!

And catch the shell.

According to the docs, “a Lambda function always runs inside a VPC owned by the Lambda service.” But you can attach your function to your own VPC, so depending on how the victim’s AWS environment is configured, you may be able to pivot around and exploit some more stuff.

Python Caesar Cipher in 15 Minutes

READER BEWARE: The code in this post is horrible.

Ever been asked to write a Caesar Cipher in Python in 15 minutes? No? Neither have I.

Anyway, here is what I accomplished. It is far from optimal. It does not take a lot into account e.g. punctuation, uppercase chars, non integer keys, negative keys, etc. But I was in a hurry.

It takes the message variable and shifts each letter to the ‘right’ by the value of the current key in keys.

#!/usr/bin/env python3

from string import ascii_lowercase

# lowercase letters
CHARACTERS = list(ascii_lowercase)

# for char in CHARACTERS:
#     print(ord(char))

message = "i cannot do this under duress"

keys = [1, 6, 9, 4, 2, 0]

# convert to unicode
message_ord = [ord(x) for x in list(message)]

for key in keys:
    new_message = ""
    for letter in message:
        # I did take care of spaces. 
        if letter == " ":
            new_message += " "
        elif ord(letter) + key > 122:
 #should prob mod something somewhere
            offset = (ord(letter) + key) - 123
            new_letter = 97 + offset
            new_message += chr(new_letter)
        else:
            new_letter = ord(letter) + key
            new_message += chr(new_letter)

    print(f"For key: '{key}' the message is '{new_message}'")

This took me 15 minutes and 36 seconds.

Tesla Solar, Powerwalls, Docker, Python, and Crypto Mining

I had Tesla solar panels and Powerwalls installed several weeks ago. I currently don’t have permission to operate (PTO) from my electricity provider, which means I can’t ship any of my surplus power back to the grid. So, after my batteries fill up for the day, I usually have power production that is going to waste. What can I do with that power?

Mine crypto, that’s what I can do! Those of you that know me IRL, know that I’ve been involved in crypto for a decade. Mining isn’t new to me, but I mostly gave up on it in 2012/2013 when I was only mining a few of Bitcoin a month and it wasn’t worth it to me anymore. Talk about a wrong decision…

I digress. I’m sitting here now producing extra power. Mining crypto with a graphics card that I already have will make me around $50-100/month and give me a chance to whip up a script in Python, which is what I truly enjoy in life. I haven’t done the actual math on it, but I think mining crypto is more profitable that selling my power back to my utility provider. It is also more fun to mine, lol.

My workstation that I’ll be mining on has a sole Gigabyte 1080 TI. It’s a little old, but they’re still going for $700 on eBay these days. I’m running Ubuntu 20.04, and I’ve decided to mine with a docker container and pointing my card at an ethash endpoint from NiceHash. I need to do some research to see if there are better options – which I assume exist.

My overall strategy for this operation will be pretty simple to start off. I’m just going to mine when my batteries are charged above a certain threshold. I set this threshold in the variable BATTERY_CHARGE_TO_START_MINING in the code. Yeah, I like long variable names.

Fortunately, Tesla provides an API to gather information from the Powerwall and there is a Python package to query it. To install this package use the following command:

pip3 install tesla_powerwall

And since I use this docker image to run the Trex Miner app, we also need to install the docker python package.

pip3 install docker

This script is pretty straightforward. I start a docker client to get the running images. I create a new Miner class with my wallet address and URL. This class has methods to start and stop the miner, as well as check if it is running.

Then, in a while loop I check my battery level and start and stop the miner as appropriate. I repeat this every HOW_OFTEN_TO_CHECK seconds.

Here is the code:

#!/usr/bin/env python3

import os
from tesla_powerwall import Powerwall
import docker
import time

POWERWALL_URL = ""  # PowerWall Gateway address goes here
EMAIL = ""  # email address that you use to login into the gateway
PASSWD = ""  # password that you use to log into the gateway
WALLET_ADDRESS = "35kwhvhyfnVnGdoWdyLqrtaHeY7RYByPfW"  # mining wallet address
MINING_URL = (
    "stratum+tcp://daggerhashimoto.usa-east.nicehash.com:3353"  # Mining url
)
# lowest battery charge where mining will start
BATTERY_CHARGE_TO_START_MINING = 50
# how often to check is battery level allows mining or not in seconds
HOW_OFTEN_TO_CHECK = 1800


def init():
    # initialize powerwall object and api
    powerwall = Powerwall(
        endpoint=POWERWALL_URL,
        timeout=10,
        http_session=None,
        verify_ssl=False,
        disable_insecure_warning=True,
        pin_version=None,
    )
    powerwall.login(PASSWD, EMAIL)

    api = powerwall.get_api()

    return powerwall, api


class Miner:
    def __init__(self, client, wallet_address, mining_url):

        self.wallet_address = wallet_address
        self.mining_url = mining_url
        self.client = client
        return

    def start_miner(self, client):
        env_vars = {
            "WALLET": WALLET_ADDRESS,
            "SERVER": MINING_URL,
            "WORKER": "Rig",
            "ALGO": "ethash",
        }
        try:
            client.containers.run(
                "ptrfrll/nv-docker-trex:cuda11",
                detach=True,
                runtime="nvidia",
                name="trex-miner",
                ports={4067: 4067},
                environment=env_vars,
            )
        except os.error as e:
            client.containers.get("trex-miner").restart()
        return

    def stop_miner(self, client):
        trex = client.containers.get("trex-miner")
        trex.stop()
        return

    def is_running(self):
        try:
            client.containers.get("trex-miner")
            return True
        except os.error:
            return False


if __name__ == "__main__":
    powerwall, api = init()

    client = docker.from_env()

    miner = Miner(client, WALLET_ADDRESS, MINING_URL)

    miner.start_miner(client)

    while True:
        # powerwall charge is satisfactory, start mining
        if not miner.is_running() and (
            api.get_system_status_soe()["percentage"]
            > BATTERY_CHARGE_TO_START_MINING
        ):
            miner.start_miner(client)
            print("miner is running or will be started")
        # powerwall charge is too low, shut off mining
        elif miner.is_running() and (
            api.get_system_status_soe()["percentage"]
            < BATTERY_CHARGE_TO_START_MINING
        ):
            print("stopping miner")
            miner.stop_miner(client)
        # try again
        time.sleep(HOW_OFTEN_TO_CHECK)

You can also find future updates of the code here.

TODO: add more options to start/stop mining e.g. if my panels/batteries are connected to the grid or not, start/stop mining based on the weather, etc.

TODO: rewrite in Golang. Trying to learn Go.

Advanced Web Attacks and Exploits -AWAE – Exam Review

> AWAE Course Overview

For people unfamiliar with this course and exam, here is a link to the Offensive security website. I’ve also written about it before, so you can check my post history. Basically the course is a giant pdf and a bunch of videos that go over web application attacks. You then get access to a lab consisting of 13 machines that are running a wide variety of vulnerable web-apps. In regards to languages/DBs/tech, this course covers VSCode, Visual Studio, JDGui, Javascript, PHP, Node, Python, Java, C#, mysql, and postgres – so it’s pretty thorough.

The exam is a 48 hour long exam where they give you access to two machines running vulnerable web-apps. You have to bypass auth on them to get administrator access and then escalate your attack to full-blown remote code execution. You’ll get two debugging machines that are running the same apps as the exam machines. You get full access to the app source code – this is a white-box course after all. You have to review the code base, and then use these debugging machines to develop ‘one-shot’ exploit script that bypasses auth and trigger RCE. I used python, as do most people, I think.

Oh yeah, and they watch you on camera the whole time.

After the exam time is up, assuming you have enough points to pass, you have another 24 hours to write an exam report documenting what you found and how you exploited it.

> How did it go?

First things first: I had to take this one twice. My power went out twice, briefly, and my father had to go to the hospital (he’s fine) during my first attempt. Even though he lives hours away, and there wasn’t much I could do, I was a little distracted. And it wasn’t like I was in front of the computer for the full 48 hours. I took a break about every 1.5 hours or so and slept 5-6 hours both nights.

Nevertheless, I still managed RCE on one of the boxes, and if I had another hour or so, I would have had an auth bypass on the second box – which would likely have let me pass. I look back and I just kind of laugh at how I failed it. I missed something simple that would have given me enough points to pass. I even knew what I needed – I just overlooked it.

I actually noticed the vulns on both boxes within an hour of looking at them. I then went down some rabbit holes for a bit and got sidetracked – especially on the box that I considered the harder one.

The second time around I crushed the exam in about 8 hours – RCE on both boxes. I had my report turned in at the 20 hour mark or so – and I was lollygagging.

If you don’t know me, my background is this: I’m not a professional developer. I don’t work in IT. I have never worked in IT. I just like computers. If I can pass this exam, so can you.

> Advice and Review

My advice for people that are preparing to take this exam is to just take their time and read the code. You need to know how to get the VSCode debugging going. It is a lifesaver. It is probably hard to pass if you don’t get it working. If you follow the code flow in a debugger, things should pop out at you. With that said, they do throw in a couple curve balls, which I bet throws some people for a loop. Now these curve balls aren’t hard to hit, per se, but someone that hasn’t been in the infosec/CTF/bug bounty world may miss these things.

Another question that I’ve been asked is, “Do you need an OSCP to do this couse?” I’ve changed my mind on this several times, and while I think an OSCP will give you a leg up, you don’t really need to have one – especially if you’re already involved the hacking/bug bounty/CTF world. If you’re coming at it straight from being a developer, it may not hurt to expose yourself to this stuff beforehand.

All in all, I’d say the exam was fair and maybe a little on the easy side. I say that as someone that failed it once, too, haha. But not only that, the exam is also a lot of fun. I love the Offensive Security exams. Some people will probably hate me for saying that, but they are a lot of fun.

Malicious qBittorrent Search Plugin: Feature or Bug?

TLDR: Read the code before you install random qbittorent plug-ins.

qBittorrent has a feature that allows you to install a search plugin to search for torrents on your favorite sites. These plugins are written in Python, and although I haven’t reviewed the qBittorrent source code, it appears as if you can simply execute arbitrary code via these plugins. qBittorrent does not seem to do any sort of sanitization.

I added a reverse shell class to an already existing search plugin. The shell should work on Windows and Linux. Although, qBittorrent seems to have some issues with what version of Python you are using. Nevertheless, be aware that unsanitized code can be ran via the search plugin feature.

Here is a link to the malicious qBittorrent search plugin.