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Stealth Access - Points: 125


The team found a web application. Find the flag without creating any logs on the server! The team was able to retrieve the source code at webapp-source.tgz. We also obtained additional information from the last mission at device_id. WARNING: This challenge's flag does not follow the standard ACI{...} format. The flag format is 32 hexadecimal characters, /[0-9a-f]{32}/.


  • Don't be foolish and browse the website carelessly
  • You might need to reset the docker container if you mess up!
  • Study the source to learn the path.


Note: This is an on-demand challenge that spins up a personalized web service for the player.

Based on the description and the hints, the goal of this challenge is to gain some information about device 36D1C3D365409932BF0B42335E661C2C without making it in the application's log. Haphazardly browsing the page, you notice this ID appearing on just about every page with some key piece of information missing. Looking at the well-documented source, you notice a logaccess function with a switch that is responsible for updating the log with your user-agent so your goal is to avoid any link that calls this function. Those links can be found inside the switch:

    case '/shipping':
    case '/quality':
    case '/billing':
    case '/orders':
    case '/sales':
    case '/inventory/cpus':
    case '/inventory/boards':

For the pages that are browsable, you need to look at the various app.get functions:

app.get('/', (req, res) => {
app.get('/shipping', (req, res) => {
app.get('/quality', (req, res) => {
app.get('/assembly', (req, res) => {
app.get('/billing', (req, res) => {
app.get('/orders', (req, res) => {
app.get('/sales', (req, res) => {
app.get('/inventory/cpu', (req, res) => {
app.get('/inventory/boards', (req, res) => {
app.get('/logs', (req, res) => {

Comparing these two, you will notice two links you can visit without being logged, '/assembly' as well as the non-pluralized /inventory/cpu. Visit these two pages, grab the extra provide information in the associated ID fields, and you have your flag.

Flag: 96f81ae1f21ddc6da946adcb0f05f6d3

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