TL;DR: Uber was vulnerable to subdomain takeover on saostatic.uber.com via Amazon CloudFront CDN. Moreover, Uber’s recently deployed Single Sign-On (SSO) system at auth.uber.com, which is based on shared cookies between all *.uber.com subdomains, was found vulnerable to session cookie theft by any compromised *.uber.com subdomain. Therefore, the impact of the subdomain takeover could be increased to Authentication Bypass of Uber’s full SSO system, yielding access to all *.uber.com subdomains protected by it (e.g. vault.uber.com, partners.uber.com, riders.uber.com, etc). Uber resolved the subdomain takeover vulnerability and granted a $5.000 bounty for the two combined issues.
I publicly disclosed a vulnerability that I responsibly disclosed to Ubiquity via the HackerOne platform. It concerned a subdomain takeover issue via Amazon Cloudfront (ping.ubnt.com) in combination with shared session cookies between subdomains on *.ubnt.com, which ultimately lead to a complete Authentication Bypass of their SSO system (sso.ubnt.com). It can be found here.