How to Detect and Kill Unauthorized Access to Your Company Accounts

How do you spot unauthorized access in your stack?

A single compromised employee account can expose your entire production database, leak proprietary code, or drain your corporate treasury. Security breaches do not always start with a massive system outage. Instead, they often begin with quiet, unauthorized access to a single communication tool, cloud console, or email account.

The most obvious sign of intrusion is an active session from an unfamiliar IP address or device. Identity providers like Okta, Google Workspace, and AWS IAM log every login attempt, but these logs are useless if nobody is watching them. You must regularly audit the active devices list and look for operating systems or locations that do not align with your team's profile.

Look for "impossible travel" alerts in your access logs. If a developer logs in from New York and then logs in from Frankfurt two hours later, you are dealing with a compromised credential or a leaked session token. Attackers frequently use virtual private networks to mask their location, but they rarely match the exact geographic footprint of your legitimate team.

Unexpected multi-factor authentication (MFA) push notifications are another clear warning sign. When an employee receives a prompt to approve a login they did not initiate, it means the attacker already possesses the correct username and password. This tactic, known as MFA fatigue, relies on spamming the user until they accidentally tap approve just to stop the notifications.

Check your OAuth integrations and authorized third-party applications regularly. Attackers who gain brief access to an account will often authorize a malicious third-party app to maintain access even after the primary password is changed. This allows them to bypass traditional login checks entirely by using persistent API tokens.

Changes to recovery details, such as backup emails, phone numbers, or security questions, are silent indicators of a takeover. Attackers modify these settings immediately to ensure they can regain access if the legitimate owner attempts a password reset. Any modification to these fields should trigger an instant notification to your security or IT administrator.

What should you do immediately when an account is compromised?

Your first action must be to terminate all active sessions globally. Changing the password is not enough because active session cookies can remain valid for days or weeks. Most modern SaaS platforms and cloud providers have a "revoke all sessions" button that invalidates current JSON Web Tokens (JWTs) and forces every device to re-authenticate.

Force a password reset immediately after killing the sessions. Use a secure, randomly generated passphrase and update the credentials in your team's password manager. If the compromised account shared credentials with other platforms, you must treat those secondary platforms as compromised and rotate their keys as well.

Audit the account's API keys, SSH keys, and personal access tokens next. Attackers frequently generate new credentials during their window of access to establish persistence. If you find any keys created around the time of the suspicious activity, delete them immediately and investigate which resources those keys accessed.

Review the account's forwarding rules and email filters. In email systems like Outlook or Gmail, attackers often set up silent forwarding rules that send all incoming messages containing keywords like "invoice," "password," or "wire" to an external inbox. This allows them to monitor business operations without ever logging back into the primary account.

Re-verify all recovery methods to ensure the attacker did not leave a backdoor. Remove any secondary email addresses, phone numbers, or authenticator apps that you do not explicitly recognize. Once the account is clean, document the timeline of the breach to understand what data might have been accessed or exfiltrated.

How do you prevent credential hijacking across your team?

Moving away from basic passwords is the most effective defense against credential theft. Password-based authentication is highly susceptible to phishing, credential stuffing, and brute-force attacks. Transition your team to passwordless authentication or enforce the use of hardware security keys like YubiKeys for all critical systems.

Implement strict session lifetime limits for admin consoles and production environments. Do not allow sessions to persist indefinitely on employee laptops. Forcing re-authentication every 12 to 24 hours for sensitive tools significantly reduces the utility of stolen session cookies.

Centralize your authentication through a single identity provider (IdP) with strict conditional access policies. This allows you to enforce security rules globally, such as blocking logins from outside specific countries or requiring managed devices to access company resources. It also simplifies offboarding, allowing you to disable access to all tools with one click.

Educate your team on social engineering tactics that bypass modern security controls. Attackers frequently impersonate IT support staff to convince employees to read out MFA codes or install remote access software. A culture where employees feel comfortable verifying unusual requests through a secondary channel, like a direct phone call, is your best defense.

Monitor your access logs using automated tools that flag anomalous behavior. Set up alerts for rapid API key creation, mass data downloads, or logins from unmanaged devices. Catching an intrusion within minutes rather than weeks is the difference between a minor incident and a company-ending data breach.