Writeup: DEF CON SG1 - NTU Sentinels Challenge 2

Writeup: DEF CON SG1 - NTU Sentinels Challenge 2

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Table of Content

Introduction

This is a writeup for the OSINT Challenge on DEFCON Singapore 1: NTU Sentinels Challenge.

Challenge Intro

Deep in an NTU research lab, genius NTU student Sann Tynell shouted “Eureka!” He had finally built his own time machine.  
Before he could react, the device slipped from his hands and activated.

Here is the attached image: Screenshot2026-04-09023416-1775673265626.png

Q1

Question

He opened his eyes in an auditorium. “Where am I?” he muttered, then paused. “…or maybe I should be asking, when am I?”
On stage, Dr Tony Tan was delivering a speech about some NTU book. He looked around and could tell that it was definitely the 90s
As he listened to the speech, something about it felt familiar.
“…I swear I’ve read a transcript of this speech before… somewhere online, maybe in some archive?”

He remembered that the speech mentioned that NTU’s 2nd Phase in its development included the establishment of an engineering institute
“If I am currently in phase 2, I can definitely get more help from the engineering institute”

Q1: According to the speech, what is the time period of Phase II in NTU’s development? (format: YYYY-YYYY)

Solution

  1. Searched google for site:".sg" nanyang development phase and a result with a PDF file shows up (Not the first result). Link at https://www.nas.gov.sg/archivesonline/data/pdfdoc/023-1995-09-25_tt.pdf
  2. Page 2 of the PDF file shows the development phases

Answer: 1986-1995

Q2

Question

The machine glitched again and he stumbled into a computer lab. He checked the date. June 19, 2000. Better. The device was still broken.
He searched the NTU website and found a lab working on powerful embedded systems.
That might fix it.
He dug through the page for contact details and found a number, then rushed to a public phone and called.

Q2: What number did he call? (format: 123-4567)

Solution

  1. Upon searching, the information from the link https://www.ntu.edu.sg/hesl/about-us, states that the Hardware & Embedded Systems Lab was previously known as Centre for High ​Performance Embedded Systems (CHiPES)
  2. Using web archive, browse www.ntu.edu.sg on the Year 2000 (https://web.archive.org/web/20001119182100/http://www.ntu.edu.sg/index_lo.htm).
  3. Navigate to Intranet > Research > Centre for High Performance Embedded Systems and you will be redirected to http://chipes.sas.ntu.edu.sg:8000/
  4. Click on Contacts and you will see the Telephone number.

Answer: 790-6966

Q3

Question

On the way, he stepped on a school newspaper which showed this article.(Download from room file)
The next article showed an Associate Professor demonstrating a satellite to students. That could help with his machine. He went back to the computer room and found the profs fax number, as he was going to type in the last 4 digits on the fax machine, the website crashed.

Q3: What is the last 4 numbers of the fax address?

Solution

  1. Searched google for “Clean sweep at supercomputing contest ntu” and a result with a PDF file shows up (https://www3.ntu.edu.sg/corpcomms2/ntunews/2000/ntunews0100.pdf)
  2. The next page from the provided challenge image shows that Mr. Chua Tai Wei was the professor on the question.
  3. With this, web archive was used again. Browse the Academic Staff Directory of the School of Electrical and Electronic Engineering (https://web.archive.org/web/20001203175700/http://www.ntu.edu.sg/eee/people/staff.htm).
  4. Next is to browse Chua Tai Wei (https://web.archive.org/web/20010107183200/http://www.ntu.edu.sg/eee/eee5/cv/chuataiwei.html). No Fax number was shown on the page.
  5. The page shows publications of Chua Tai Wei which is titled Merlion L & S Band System. With this, search for the publication title on Google.
  6. A PDF file will show up and the PDF file contains the details of the authors.

Answer: 0415

Q4

Question

The device glitched again and he stumbled forward. He pulled out his phone. To his surprise, he had signal.
The year showed 2009.
He then looked up at the building in front of him and frowned.
“This is supposed to be our university clinic…”
Something felt off. The entrance looked different, and there was a large banner stretched across the front that he didn’t recognise.
“If I know what this place was being used for… maybe the people inside can help.”

Q4: What is the name of the building as seen on the banner? (ignore the spelling error)

Solution

  1. Searched Google Maps for NTU Clinic. Multiple results show up but University Health Service is more applicable.
  2. Next, is to use the street view and click See more dates and use 2009.
  3. The banner will show “Welcome to International Student Centre”.

Answer: International Student Centre

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