Justus Perlwitz

2025-04-23 • bandit overthewire

The article contains a walkthrough for all 34 levels of the Bandit wargame on OverTheWire. It provides instructions on how to solve each level and includes links to each level. The author also encourages readers to donate to OverT...

2025-03-11 • python mathematics resources math capture the flag 2023 nclib

The text is a writeup for the Fetch The Flag 2023 Quick Maths challenge. The author made a program to improve math grades, but it had the opposite effect. The challenge server prompts users to solve math challenges and times them ...

2025-03-07 • automotive industry rtos ecu erika enterprise autosar

The text discusses the use of Real-Time Operating Systems (RTOS) in Electronic Control Units (ECUs) in cars to ensure safety and efficiency. It mentions the development of ERIKA Enterprise, an AUTOSAR compatible OS, and provides l...

2025-02-07 • linux gcc nixos and nix package management embedded systems gdb ghidra memory management mips

The text discusses how to compile static gdbserver for MIPS with Nix, and the issues faced when running gdbserver on embedded devices. It also explains the process memory issues and how to fix them.

2025-01-24 • technology ios and ipados development apple web browsers safari wi-fi standards and technologies mozilla firefox nfc akihabara

The text discusses the use of adhesive Near-Field Communication (NFC) tags, specifically the AD Bullseye NFC NTAG213 from Avery Dennison Smartrac. It provides details about the product, including the purchase quantity and cost. Th...

2025-01-11 • cybersecurity linux networking nixos and nix package management linpeas

The text provides various techniques for post-exploit Linux, including adding yourself to the current user's authorized SSH keys, using reverse shell, LinPEAS, and compiling and bundling with Nix.

2025-01-08 • cybersecurity networking email security and infrastructure ssl/tls network ports

The text discusses the Simple Mail Transfer Protocol (SMTP) and the three different ports used for it. It explains the confusion around the ports, the issues with port 25, and the security measures to mitigate spam-related problem...

2025-01-07 • cybersecurity digital dns and domain name services network services

The article explains how to run a full DNS request for a domain using dig. It describes the sequence of queries that dig performs and the information it retrieves. It also explains the recursive nature of DNS name resolution and t...

2024-12-26 • cybersecurity cryptography weak rsa hack the box

The article contains a writeup for the retired Hack The Box Weak RSA challenge. It explains how to decrypt the message and get the flag by unpacking the challenge archive file, decoding the public key, deriving the private key, an...

2024-12-22 • computer science finite field mathematics resources diffie-hellman

The text explains how to derive p and g used in Finite Field Diffie-Hellman. It shows how to derive the order of g and how to find the order of every integer below the prime number. It also provides a convenience function that ret...

2024-12-21 • macos dns and domain name services anki

The author describes how to fix mDNS on macOS Sequoia after upgrading to the new version. The author's MacBook stopped responding when pinging its host name lithium.local, and the Anki sync server running on it became unreachable....

2024-12-11 • cybersecurity standardized testing japanese

The Information Security Management Examination in Japan is a multiple-choice exam administered by the Information-technology Promotion Agency (IPA) and covers basic knowledge and Information Security Management System (ISMS) rela...

2024-11-21 • japan cybersecurity malware computer virus

The Ministry of Economy, Trade, and Industry (METI) of Japan published a guideline on preventing computer systems from getting infected with malware and what to do when they’re infected. The guide was first published in 1995 and l...

2024-09-18 • web development cross-site scripting content security policy sekai ctf tagless

The article is a writeup for the SekaiCTF 2024 Tagless challenge. It discusses the vulnerabilities in the app, including HTTP error handler, MIME types, and untrusted user input. It also provides recommended measures for system ad...

2024-09-17 • cybersecurity penetration testing hack the box shocker shellshock

The text is a writeup for the retired Hack The Box Shocker machine, which is vulnerable to the Shellshock bug. The machine's IP address is 10.10.10.56, and the time required to complete it is 3 hours. The solution involves exploit...

2024-09-17 • docker race condition /proc filesystem local file inclusion starliner python exploit sekai ctf funny lfr app.py

The text is a writeup for the SekaiCTF 2024 Funny lfr machine. It includes the challenge address, category, time required, date solved, and notes. The author provides a solution summary and steps to solve the challenge. The text a...