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Bypass subscription

Medium
I
Imgur
Submitted None
Reported by 1a2er3d

Vulnerability Details

Technical details and impact analysis

Business Logic Errors
Hello team! You can bypass avatar subscriptions. Thus, without connecting a subscription - it's free. A list of all avatars is available at the address below, with a GET request: ``` :method: GET :authority: api.imgur.com :scheme: https :path: /account/v1/accounts/me/avatars?client_id=YOU CLIENT ID user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36 dnt: 1 accept: */* origin: https://imgur.com sec-fetch-site: same-site sec-fetch-mode: cors sec-fetch-dest: empty referer: https://imgur.com/ accept-encoding: gzip, deflate, br accept-language: ru,en-US;q=0.9,en;q=0.8,uk;q=0.7 YOU COOKIE ``` But the subscription on the site is paid and without this trick it cannot be bypassed. We use " " - space in front of the icon name and get paid icon for free. Below is the request to send ``` :method: PATCH :authority: api.imgur.com :scheme: https :path: /account/v1/accounts/me?client_id=YOU CLIENT ID accept: application/vnd.imgur.v1+json dnt: 1 user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36 content-type: application/vnd.imgur.v1+json origin: https://imgur.com sec-fetch-site: same-site sec-fetch-mode: cors sec-fetch-dest: empty referer: https://imgur.com/ accept-encoding: gzip, deflate, br accept-language: ru,en-US;q=0.9,en;q=0.8,uk;q=0.7 YOU COOKIE Content-Length: 73 { "avatar_id": " subscription/spooktober-pumpkin", "id": YOU ID } ``` __Small recommendation __ The point is that you use "TRIM" after checking by name. It turns out TRIM strips the space and it bypasses the check. **I think this information will be useful to you.** ## Impact We connect a paid avatar - for free. Thus, we bypass the subscription.

Report Details

Additional information and metadata

State

Closed

Substate

Resolved

Submitted

Weakness

Business Logic Errors