And then there are the bugs that greet you like an uninvited guest — quietly waiting on a public server, carrying more information than it should.

This story is about the last kind.

While exploring the ConfirmTkt web application under the Ixigo Bug Bounty Program, I came across something unusual: A backup ZIP file named rbooking.zip sitting openly on the production domain.

No authentication. No restrictions. Just a simple download link away.

And as it turned out, that one ZIP file revealed far more about the application's structure than any public site ever should.

🔍 The Discovery — A Backup File in the Wild

I was mapping the application when I noticed the endpoint:

http://www.redacted.com/rbooking.zip

Out of curiosity, I opened it in the browser. Instead of an error or a 403, the file began downloading instantly.

No redirects. No warnings. Just a direct 200 OK.

A whole backup ZIP archive… exposed to the internet.

This was the moment I knew I had stumbled into a classic yet impactful oversight.

📂 What Was Inside the ZIP?

Once extracted, the ZIP revealed a structure of front-end assets:

  • index.html
  • CSS files
  • JavaScript files
  • Layout components
  • Scripts and static assets
  • Other internal structure files

At first glance, it looked harmless — just static content.

But then reality set in.

Backup files often contain more than people realize.

Older versions. Deprecated files. Forgotten logic. Hardcoded URLs. Commented-out API calls. Development artifacts developers never expected anyone outside the team to see.

A single ZIP can tell you how the application thinks.

And that's exactly why attackers love them.

🧠 Why Backup Files Are More Dangerous Than They Look

To many developers, backup files feel harmless — "just an old copy." But to attackers, they're reconnaissance gold.

Here's why:

🔹 1. Revealing the Application's Internal Structure

File paths, directory layout, and naming conventions can expose:

  • hidden routes
  • internal logic flow
  • API architecture
  • endpoints not visible on the live site

🔹 2. Discovery of Deprecated or Unused Code

Older assets often contain:

  • outdated JS functions
  • test endpoints
  • debug logic
  • commented API tokens
  • hardcoded URLs

These are often less secure than the live code.

🔹 3. Sensitive Information Leakage

Sometimes backup ZIPs contain:

  • staging files
  • error logs
  • leftover config files
  • .env-like references
  • prototype modules

Even one misfiled backup can expose critical details.

🔹 4. Laying Groundwork for Future Exploits

Even "non-sensitive" files can reveal:

  • how authentication works
  • how forms validate data
  • hidden parameters in API calls
  • logic flow attackers can manipulate

Attackers rarely need a full exploit — they just need clues.

And this ZIP file offered plenty.

🎯 Reporting the Issue

Once I confirmed the exposure, I documented everything:

  • The direct access link
  • The nature of the files exposed
  • Potential security impact
  • Steps to reproduce
  • Recommended remediation strategies

The triage team reviewed the finding, validated the issue, and closed it after implementing fixes. It's always satisfying to see organizations take security seriously and respond quickly.

🛠️ How I Recommended Fixing It

To ensure the issue wouldn't happen again, I suggested:

🔒 1. Remove the ZIP From the Server

Backup archives should never remain in a public directory.

🚫 2. Block ZIP Access

Server configs can easily deny access:

Apache (.htaccess):

<FilesMatch "\.(zip|rar|tar|gz)$">
    Deny from all
</FilesMatch>

NGINX:

location ~* \.(zip|rar|tar|gz)$ {
    deny all;
}

🔍 3. Review the ZIP Contents Carefully

Look for:

  • leaked tokens
  • debug code
  • unused endpoints
  • outdated logic

🔄 4. Improve CI/CD Hygiene

Ensure builds don't include:

  • backup files
  • temporary archives
  • developer leftovers

This is simple to implement but prevents a surprising number of exposures.

💡 Final Thoughts: The Value of Quiet Vulnerabilities

Not every vulnerability is about advanced exploitation. Sometimes, it's about spotting something that shouldn't be there.

A single ZIP file can reveal:

  • a roadmap of the application
  • deprecated behavior
  • hidden attack surfaces
  • clues attackers can chain

Finding rbooking.zip reminded me of something I've seen again and again:

Security isn't only about blocking attacks — it's about preventing unintentional exposure.

And in the world of bug bounty, those exposures are often hiding in plain sight.

On to the next hunt. 🐞🔍