One of the biggest risks inside law firms is not always an outside attacker. It is uncontrolled internal access to sensitive information.

Microsoft 365 gives firms flexible options for document storage through SharePoint and OneDrive, but that flexibility only helps if it is structured intentionally. Files should be stored in the right places, permissions should be based on role or matter, and access should be reviewed regularly.

Without that structure, it becomes far too easy for everyone to have access to everything. That creates unnecessary exposure around client confidentiality, case materials, internal financial information, and firm-wide risk.

Microsoft’s own SharePoint security planning guidance is a helpful external resource here, but most firms still need practical help applying those settings in a way that works for a real legal environment.

Many firms assume that because they are using Microsoft 365, their email is already secure. That is only partially true.

Email encryption must be configured properly and be simple enough for attorneys and staff to actually use. External sharing should be controlled, and additional email protection should sit on top of Microsoft’s native tools to help reduce impersonation, malicious attachments, and account takeover attempts.

This matters because attorneys and support staff are busy. They are often moving quickly between deadlines, client requests, court communications, and opposing counsel. Attackers know that and take advantage of it.

CISA’s guidance on business email compromise is a strong reminder that trusted-looking email remains one of the easiest ways for bad actors to get into a professional services environment.

Many law firms are not actively monitoring login activity in Microsoft 365. Attackers know this, and account takeover remains one of the most common ways they gain access to business systems.

For a law firm, an account takeover is not just a login problem. Once a bad actor gains access to a mailbox or user account, they may be able to read confidential email, review stored documents, harvest client data, set up forwarding rules, impersonate attorneys or staff, and use that trusted account to widen their access across the environment.

The consequences can be serious. A compromised Microsoft 365 account can lead to data exposure, operational disruption, reputational damage, client trust issues, and potentially legal or regulatory fallout if sensitive information is accessed, stolen, or misused. In a law firm, that can quickly become far more than a technical inconvenience.

At a minimum, firms should have multi-factor authentication enforced, alerts configured for suspicious sign-ins, and regular review of sign-in logs and risky-user activity. More mature environments add 24/7 SOC monitoring and automated response so suspicious logins can be investigated and contained before they turn into something bigger.

Microsoft’s guidance on risk-based sign-in protection in Microsoft Entra ID is a useful external resource here and helps show why monitoring user behavior matters just as much as enforcing strong passwords and MFA.

Microsoft protects their platform. They do not fully protect your data.

Law firms should have third-party backups for email, SharePoint, and OneDrive. That protects against accidental deletion, malicious activity, retention gaps, and ransomware-related data loss.

If you cannot confidently restore a mailbox, document library, or individual file, then you do not really have a backup strategy. You have an assumption.

Microsoft’s retention documentation is helpful here because it explains the difference between retention and true backup. Those are not the same thing, and many firms do not realize that until they need to recover something important.

The biggest risk to your firm is not technology alone. It is people operating under pressure.

Not because they are careless, but because they are busy. Attorneys and staff are often focused on deadlines, court requirements, client demands, and getting through a packed day as efficiently as possible. That is exactly the kind of environment attackers love.

That is why phishing awareness training and regular testing are so important. A strong program helps users slow down, recognize suspicious behavior, and build better instincts over time.

CISA’s Secure Our World initiative is a helpful public resource, but law firms typically benefit most from ongoing training and simulation tied directly to how their teams actually work.