Exposed .env File Leads To API Key Leak & Financial Impact

Exposed .env File Leads To API Key Leak & Financial Impact | by 1sherlok - Freedium Milestone: 20GB Reached We’ve reached 20GB of stored data — thank you for helping us grow! Patreon Ko-fi Liberapay Close < Go to the original Exposed .env File Leads To API Key Leak & Financial Impact Hello everyone, I'm Sherlok, and today I'd like to share how I discovered an exposed .env file that led to leaked API credentials and real… 1sherlok Follow ~3 min read · April 3, 2026 (Updated: April 3, 2026) · Free: Yes Hello everyone, I'm Sherlok, and today I'd like to share how I discovered an exposed .env file that led to leaked API credentials and real financial impact. Twitter: https://x.com/sherl8k Let's begin: Let me quickly mention a browser extension I regularly use that helps identify vulnerabilities with zero interaction: https://github.com/davtur19/DotGit It runs in the background and alerts you when it detects: .git/.svn/.hg folders .env files .DS_Store It was precisely because of this that I was able to find the vulnerability we'll be discussing today Open /.env While browsing some websites, I saw a notification about an open .env file and immediately decided to check it out. I was very pleased with what I saw, as I noticed the following API keys there: At this point, it was clear that these credentials could potentially be used to interact with external services. The next step was to verify whether they were valid. Well then, let's see if they work: I used the following curl commands: 1. Successful authenticated request: This confirmed that the credentials were active and usable. 2. Access to account balance I then tested whether I could access account-related data: At this point, it became clear that the exposed credentials were not only valid -but also tied to a billing account. Impact This kind of issue might look simple, but it has serious implications. An attacker could: Consume the company's API balance (financial loss) Automate large-scale API usage Exhaust quota and cause denial of service Use the API for unauthorized data enrichment Integrate the stolen API into their own tools or services And the most important part - no authentication to the application itself was required . Everything was possible using only the leaked .env file. Why Exposing .env Is Dangerous The .env file is one of the most sensitive files in any application. It usually contains: API keys Secrets Database credentials Internal service endpoints Tokens and private configuration Exposing it is essentially the same as giving an attacker direct access to the application's internal secrets . Unlike typical vulnerabilities, this does not require exploitation- the data is simply handed over. Root Cause (in plain terms) This was not a complex vulnerability - just a classic misconfiguration: Sensitive .env file exposed publicly No server-side restriction on access Secrets stored in plaintext No additional protection (IP restriction, rotation, etc.) Basically, the server allowed direct access to a file that should never be public. Fix / Recommendation To properly address this issue, the backend should: Block access to .env files at the web server level Store secrets outside of the web root Rotate all leaked credentials immediately Monitor usage for abuse Issues like this are a good reminder that security doesn't always fail in complex ways — sometimes it's just one exposed file. The issue was responsibly disclosed to the company. All credentials were rotated after the report. Anyway, that's it for this one. Happy hacking 👾 #bug-bounty #bug-bounty-tips #bug-bounty-writeup #cybersecurity #pentesting Reporting a Problem Sometimes we have problems displaying some Medium posts. If you have a problem that some images aren't loading - try using VPN. Probably you have problem with access to Medium CDN (or fucking Cloudflare's bot detection algorithms are blocking you).