If you suspect an account may be compromised, use the checklist below to ensure that your users' accounts (e.g. compromised/hijacked accounts) are secure. Work with affected users to complete the end-user Gmail Security Checklist.
Temporarily suspend the suspected compromised user account
- Suspend a user to prevent unauthorized access.
- Block access to G Suite by resetting the user's sign-in cookies.
- Investigate the potentially unauthorized activity and restore the account. You may also consider enrolling the domain in 2-step verification.
- Ask the affected user to review their recovery address and complete the Gmail security checklist.
Revoke access to the affected account
- Follow the steps in Reset a user's password.
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Revoke OAuth 2.0 tokens for the user.
Some applications that use the OAuth 2.0 authentication method will stop accessing data after you reset a user's password. The user must login with their account name and new password to receive a new OAuth 2.0 token. - Block access to G Suite by resetting the user's sign-in cookies.
- Remove App passwords that have been created by the user.
For full checklist about administrator security, kindly visit: Administrator security checklist