## Writeup in 30 seconds
1. goto `/profile/1` to know the target is login as `[email protected]`2. with analyzing you can find the feature that removing `+` in email's name when sending messages    * send to `[email protected]` will actually to `[email protected]`    * is this feature exists when login?2. do port forwarding and use http://127.0.0.1:3000 for connection3. register an account in dropbox.com with email `[email protected]`4. login footbook with dropbox oauth5. you can see the flaaaaaag
## Some interesting things
1. I've tested some oauth providers, only `dropbox.com` gives unauthorized email.    * But Dropbox will say the email is not verified in `extra_info`, don't ignore it!2. You guys are really creative :p, some interesting fake flags posted on Footbook:```hitcon{why_s0_s3ri0u$!!}hitcon{lfi_d03snt_sav3s_ou4_a$$}hitcon{wow_n1c3_lf1}hitcon{1_f00t_3q4l5_1_fl4g}hitcon{CSRF_for_fun_and_pr0f1t!}hitcon{f00t_1n_y0ur_m0uth?}hitcon{f00tb00k_1z_d4_r3al_fB!!!}hitcon{s3xy_f4c3b00k_>_<}hitcon{f00tbook?_flagbook?_2333}```