How to Execute Command (with Arguments) on Multiple Windows Servers using PowerShell

This PowerShell script is useful when you have access to multiple Windows servers and need to run the same command on all of them. For example, I needed to run an executable that can be found on both nodes (AppNode1, AppNode2) in path C:\scripts\myapp.exe of a multi-node cluster:

How To Catch EBUSY Event on Windows using NodeJS

Introduction During a debugging session of one of our NodeJS microservices misbehaving on a Windows Server 2019 instances, I opened the microservice log to begin investigating the faulty behavior. But when I scrolled down to the timestamp where I was supposed to start investigating, I found out that the log was full of the following

Dotless Emails Regex Validation

Introduction One of our customers recently attempted (for reason unknown to us) to log into our platform using Okta Single Sign On (SSO) and OpenID-Connect with emails missing a top-level domain (TLD) while they could log in just fine with a standard email address. While most of us in the day-to-day use the standard email

Hack The Box ‘Archetype’ Challenge

What is Hack The Box? Hack The Box is a website offering vulnerable machines for practising hacking skills. The goal of the ‘Labs’ are to hack into the system and capture the flag (CTF) which can be found in a text file in the desktop of a regular and an administrator user. On my pursuit

Debugging NodeJS Microservice with Shared Storage on Kubernetes

Introduction One of our largest customer recently had a problem loading a list of resources from our web application. The problem was a blocker for the customer and required to identify the problem and provide a workaround, if possible. I was assigned the task as I was the SME in this area (NodeJS microservices, infrastructure

Installing PiHole On Raspberry Pi 4, MicroK8s running Ubuntu 20.04 (focal)

PiHole, What’s That? The Wikipedia definition should be sufficient in explaining what the software does: Pi-hole or Pihole is a Linux network-level advertisement and Internet tracker blocking application which acts as a DNS sinkhole and optionally a DHCP server, intended for use on a private network https://en.wikipedia.org/wiki/Pi-hole I wanted to deploy it for a few

How to Run a Sequential gulp.js Task using PowerShell

One of our largest and strategic customer recently requested to be able to execute an automated ETL pipeline from one of their Windows multinode cluster in a sequential manner. The ETL pipeline has basically 3-stages: Initialize an import from their many data sources into a consolidated database on master node. After the import step finishes,

How To Trace/Read RabbitMQ Messages

Introduction This week, I needed to debug a production issue where one of the critical ReactJS applications happened to load exactly after 60 seconds. When I opened the browser development tools network tab, I saw that the request was stuck in Pending state indicating that it was waiting for the server to respond. As I

Angstrom CTF2021 | Exploiting Python Pickle in Flask Web App

Recently, I became interested in understanding a bit more about web application exploitation. This interest evolved with my daily work with web applications over the last few years, reviewing already developed web application source code, modifying it at times in order to resolve a customer issue and needing to dive deep and debug customer problems

3-Way Data Migration between Support Systems

The company I work for decided a few months ago that we’ll be moving all customer tickets and assets from two separate systems (one for chat and one for old-school tickets) into a new, integrated system which provides both capabilites. My task was to perform the migration between the systems. Even though I’m not data