> For the complete documentation index, see [llms.txt](https://ctf.zeyu2001.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ctf.zeyu2001.com/2022/nahamcon-ctf-2022/two-for-one.md). # Two For One In this challenge, we had to authenticate as the admin user in a 2FA-enabled environment. The feedback feature of the site had an XSS vulnerability, allowing us to perform a CSRF on the admin to reset their 2FA code. ```markup ``` This allowed us to steal the 2FA token: ```json {"url":"otpauth://totp/Fort%20Knox:admin?secret=POYRTZ7WQMGBJZIX&issuer=Fort%20Knox"} ``` This token can then be used by any authenticator application (e.g. Google Authenticator) to generate the admin 2FA codes. With the 2FA code in hand, we can once again perform a CSRF to steal the admin's secrets: ```markup ``` The flag is contained in the secret. ```bash ~ echo "eyJ2YWx1ZSI6ImZsYWd7OTY3MTBlYTZiZTkxNjMyNmY5NmRlMDAzYzFjYzk3Y2J9In0K" | base64 -d {"value":"flag{96710ea6be916326f96de003c1cc97cb}"} ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://ctf.zeyu2001.com/2022/nahamcon-ctf-2022/two-for-one.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.