Bug Bounty ShortsHow I Found Pre-Account Takeover Vulnerabilities
This bug involved an Authentication Bypass through insufficient input validation of URL parameters, enabling Account Takeover (ATO). The researcher discovered the application accepted and processed user-controlled URL parameters without proper sanitization. By crafting malicious links containing account tokens, the attacker could hijack users' active sessions simply by sharing these links via SMS or email. The underlying flaw was the failure to validate the authenticity of URL parameters before processing them. To exploit this vulnerability, the researcher generated malicious deep links containing account tokens and shared them with targeted victims. Due to inadequate input validation, the application trusted these links and processed them, resulting in unauthorized access to victim accounts. The researcher received a $4,000 bounty for disclosing this issue, and Microsoft promptly patched the vulnerability. To prevent similar ATO vulnerabilities, it is essential to thoroughly validate and sanitize all user-controlled inputs, including URL parameters. Key lesson: Always verify the authenticity of user-supplied data before processing it. #BugBounty #Cybersecurity #AuthenticationTakeover #InputValidation #Infosec
