MFA is enabled. Your password is strong. But could an attacker still access your account?
Unfortunately, yes.
One increasingly important technique businesses should understand is session hijacking.
When you sign into a website or cloud service, your browser receives a session token that tells the service you’ve already authenticated. This is what keeps you logged in while you move between emails, documents and applications.
If an attacker manages to steal that session token, they may be able to use your existing authenticated session without knowing your password.
Why is this important?
Because MFA primarily protects the login process.
A stolen session can potentially allow an attacker to operate after the legitimate user has already completed MFA.
Session information can be targeted through malware, sophisticated phishing attacks, vulnerable applications and compromised browsers. MITRE ATT&CK specifically tracks the theft of web session cookies as a recognised attack technique.
What should businesses watch for?
Some warning signs include:
🔹 Sign-ins from unusual locations or devices
🔹 Unexpected email activity
🔹 New mailbox forwarding rules
🔹 Unusual access to business applications
🔹 Unexpected MFA or login prompts
🔹 Suspicious browser behaviour
🔹 Account activity that continues after a password reset
None of these automatically means an account has been compromised, but they are signals worth investigating.
How can you reduce the risk?
A strong security strategy should combine:
MFA + Endpoint Protection + Conditional Access + Identity Monitoring + Security Awareness + Incident Response
For Microsoft 365 businesses, this can include using managed devices, Conditional Access policies, phishing-resistant authentication where appropriate, endpoint protection and monitoring for unusual identity activity.
The Takeaway
MFA is essential — but it shouldn’t be the finish line.
Modern account security needs to protect the entire user session, not just the moment someone enters their password.
If your business uses Microsoft 365 or other cloud applications, now is a good time to ask:
“What happens if an attacker gets past the login?”
Credit:
Read our full article to learn how session hijacking works, what warning signs to look for and what businesses can do to reduce their exposure.
Based on the topic covered in Tech Insider’s 2026 article, “How to Detect & Stop Session Hijacking”, with the content independently rewritten for business readers.“