From Curiosity to CVE: How I Found a CSRF Privilege Escalation Bug
Table of contents
- How I Found the Vulnerability
- Technical Breakdown
- Responsible Disclosure Process
- Why This Matters to Me
- Lessons Learned
- What's Next?
After reading this writeup you should be familiar with a Cross-Site Request Forgery (CSRF) vulnerability in [redacted] discovered during a responsible disclosure program. The vulnerability potentially allowed attackers to [redacted] if a victim clicked a specific URL without prior knowledge.
How I Found the Vulnerability:
During my exploratory review of the login flow, I noticed several elements could introduce cross-site vulnerabilities. This indicated that authentication tokens were being handled in a way that potentially left them exposed to cross-origin requests, leading me to probe deeper.
Technical Breakdown:
- Vulnerability Type: Cross-Site Request Forgery
- Affected Component: Authentication Module
- Root Cause Analysis: Inadequate validation of origin in authentication processes
- Impact: Potential for attackers to perform actions on behalf of authorized users
- Attack Vector: Crafty constructed URLs that victims would click
- Technical Details: The application was not checking if the request originated from a legitimate source, allowing cross-domain requests to succeed.
Responsible Disclosure Process:
- Discovered the vulnerability on [redacted date]
- Created a detailed report with proof-of-concept
- Privately reported to the vendor's disclosure program
- Maintained communication during the patching process
- Received acknowledgment from the vendor on [redacted date]
Why This Matters to Me:
Security vulnerabilities like this highlight the importance of proper validation across all aspects of an application. As ethical hackers, we strive to make the internet a security and privacy-oriented, but durable of importance.
Lessons Learned:
- Always check for proper token validation when testing web applications
- CSRF vulnerabilities can often be hidden in plain sight in basic functionality like login flows
- Understanding the user flow thoroughly helps identify where security controls might be missing
- Documentation is crucial when reporting findings
What's Next?
As vendors implement more robust CSRF protections, I expect that vigilant testing for related variations will continue to be important. Don't be afraid to get creative if you're beginning an exploration of web security - sometimes the simplest tests yield the most interesting results!