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This repository has been archived by the owner on Jul 17, 2021. It is now read-only.

Verification Code Hijacking

Critical
Kenny2github published GHSA-99cr-hvf7-85g9 Nov 19, 2020

Package

No package listed

Affected versions

<a603769

Patched versions

a603769

Description

Impact

Potentially affects all users of ScratchVerifier. An attacker can hijack the verification process to log into someone else's account on any site that uses ScratchVerifier for logins:

  1. User starts login process
  2. Attacker attempts login for user, and is given the same verification code
  3. User comments code as part of their normal login
  4. Before user can, attacker completes the login process now that the code is commented
  5. User gets a failed login and attacker now has control of the account

Patches

Since commit a603769 starting a login twice will generate different verification codes, causing both user and attacker login to fail.

Workarounds

For those that use the official host, none necessary once ScratchVerifier is updated.
For clients that rely on a clone of ScratchVerifier not hosted by the developers, their users may attempt to finish the login process as soon as possible after commenting the code. There is no reliable way for the attacker to know before the user can finish the process that the user has commented the code, so this vulnerability only really affects those who comment the code and then take several seconds before finishing the login.

Severity

Critical

CVE ID

CVE-2020-26236

Weaknesses

No CWEs

Credits