Thoughts, writeups, and experiments in cybersecurity and coding
mis4nthr0pia Challenge Overview This CTF challenge presents an eBPF-based network firewall that filters TCP traffic for the keyword “flag” and the character ‘%’. The objective is to retrieve a flag from an nginx web server at 35.227.38.232:5000 serving /flag.html. Vulnerability Analysis Firewall Implementation The firewall is implemented as an eBPF program (firewall.c) attached to both ingress and egress TC … Read more
Challenge Overview The challenge presents a scenario where a protest against soaring housing prices (gentrification) occurred in Mexico City in July 2025. We are given a link to a Jiji Press article (referenced as 2025070500264) featuring a photo of a vandalized store. The goal is to identify the store and find its opening date (local time) in YYYY/MM/DD format. Initial Assumptions … Read more
Challenge Overview We are presented with a scenario involving a lattice tower of a communications facility that was damaged during an earthquake in Japan in December 2025. The objective is to identify the official technical name of this facility as a communications hub (its Shuyokyoku or “Accommodation Station” name), which differs from the common name reported in news articles. Initial Assumptions … Read more
Challenge Overview The task is to determine the legal name of the user debeyohiru/furaigo5. We are given access to their public profile page and are instructed to identify the real name in Latin alphabet, ignoring Kanji or Hiragana. Initial Assumptions Investigation Process Step 1: Inspect the Profile Source Step 2: Examine the JavaScript File Key Findings Final Flag … Read more
Challenge Overview The goal of this challenge was to identify the nearest Tokyo Metro station to the workplace of the target, “Lilica”. We were provided with: Initial Assumptions Investigation Process Step 1: Analyzing the Image (The Physical Clue) Step 2: Analyzing Digital Footprints (The Profession) Step 3: Geolocation of the Workplace Step 4: Determining the Station Key … Read more
Challenge overview The objective of this challenge is to determine lilica’s real name using publicly available information. The answer should be in the Latin alphabet (romaji). Flag format: Example (not the solution): Initial assumptions Investigation process Key findings Final flag / answer Notes & takeaways
Challenge overview Lilica hosts a personal website using a third-party hosting service. The website itself is not violating any terms, but the objective is to identify the abuse-reporting email address of the hosting provider. Flag format: Warning: Do not send emails to this address. The task is only to identify it via OSINT. Initial assumptions Investigation process … Read more
Challenge overview Lilica ran a personal website linked from her social media account @twilight_lilica. Your task is to determine when the domain name of her personal website was registered in YYYY/MM/DD format. Flag format: Initial assumptions From lilica’s social media activity, she linked to a domain that appears to be a personal portfolio or profile … Read more
Challenge overview Lilica is also interested in VR, and some activity has been observed in the future. The objective of this challenge is to identify the VRChat user ID which lilica was using as of 2026. VRChat user information can be viewed in a web browser. Flag format: Example (not the solution): Initial assumptions Investigation process … Read more
Challenge Overview An image of Tokyo Station was published on rain’s blog. However, visual inspection suggests that the image is AI-generated rather than a real photograph. The objective of this challenge is to determine which AI tool was used to generate the image, using only lawful OSINT techniques. Flag format: Example (not the solution): Initial … Read more