One of my favorite CTF challenge categories is OSINT. I enjoy the process of gathering information and piecing them together to solve a challenge. Just like when Sherlock Holmes gathers clues to solve a mystery.
Today challenge is called “Authentic Chinese Food” from CSAW CTF 2024. The challenge description is as follows:
Quote
I visited this gourmet restaurant a while back, but I’m worried about the health and safety rating of it. Could you check it for me? Oh, and before I forget, could you tell me when the building was built, as well as the name of the LLC that owns it?
Flag Format: csawctf{HealthGrade_YearBuilt_LLCName} (Name does not include LLC, replace all spaces with underscores)
Grade is the MOST RECENT grade, and does not have to be a letter.
With this detailed image, it does not take long to find the address of the restaurant. Simply ask Google Lens to search for similar images and it will return the address of the restaurant.
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Exact location is: 423 Fulton Street, Brooklyn, NY 11201
Next, I will search for the health and safety rating of the restaurant. I will use yelp.com
About Health Scores
Yelp gets this data from Health Department intelligence (HDI), a leading provider of health department data analytics.
There are many public records about real-estate in USA, especially for this commercial one. Exploring around led me to this website, where I do not have to pay to view the owner of the building. It also included year built “1920”.
Combine everything we got:
csawctf{Grade_Pending_1920_BNN_Fulton_Flushing_Owner}