This article is a part of our Vulnerability Database (back to index)
Cross-Site Request Forgery occurrences in Save-server
save-server (npm package) before version 1.05 is affected by a CSRF vulnerability, as there is no CSRF mitigation (Tokens etc.). The fix introduced in version version 1.05 unintentionally breaks uploading so version v1.0.7 is the fixed version. This is patched by implementing Double submit. The CSRF attack would require you to navigate to a malicious site while you have an active session with Save-Server (Session key stored in cookies). The malicious user would then be able to perform some actions, including uploading/deleting files and adding redirects. If you are logged in as root, this attack is significantly more severe. They can in addition create, delete and update users. If they updated the password of a user, that user's files would then be available. If the root password is updated, all files would be visible if they logged in with the new password. Note that due to the same origin policy malicious actors cannot view the gallery or the response of any of the methods, nor be sure they succeeded. This issue has been patched in version 1.0.7. (2020-08-04, CVE-2020-15135)
Why Cross-Site Request Forgery can be dangerous
The absence of Anti-CSRF tokens may lead to a Cross-Site Request Forgery attack that can result in executing a specific application action as another logged in user, e.g. steal their account by changing their email and password or silently adding a new admin user account when executed from the administrator account.
The attacker may copy one of your web application forms, e.g. email/password change form.
The webpage will contain a form with the exact set of fields as the original application but with input values already provided and the submit button replaced with a Javascript code causing auto-submission. When the page is accessed the form will be immediately submitted and page contents replaced with a valid content or a redirect to your original application.
One of your application users who is already logged in can be then tricked to navigate to such malicious page e.g. by clicking a link in a phishing email, and the pre-populated form content will be submitted to your application like it would be submitted by your user.