Cyber Security for Professional Services Firms
Law firms, accountants and consultancies are trusted with client data that attackers want. Client expectations on security are rising every year.
Why this matters to professional services
Professional services firms sit on highly sensitive client data and are increasingly judged on how they protect it. A serious incident can end a client relationship and trigger regulatory and insurance consequences in the same week.
Most firms now run cloud-first stacks built around Microsoft 365 or Google Workspace, with a long tail of SaaS tools. Securing that estate well requires more than the defaults.
DefendVista helps professional services firms put credible, evidence-based security in place that holds up under client due diligence and regulator scrutiny.
The attacks we see hitting professional services
Business email compromise
Highly targeted attacks against partners and finance leads that lead to wire fraud or client data exposure.
Ransomware with double extortion
Encryption combined with threats to publish client data unless paid.
Insider risk
Departing staff retaining access to client matters and contact lists.
SaaS sprawl
Shadow IT and unmanaged SaaS apps holding client data outside any controlled environment.
Targeted phishing
Sophisticated lures that mimic clients, courts or regulators.
What an incident actually costs you
- Direct financial loss from wire fraud
- Loss of client engagements following a breach
- Regulatory action from the SRA, ICAEW or equivalent bodies
- ICO investigation and notification obligations
- Insurance premium increases or refusal of cover
Where we usually find the gaps
- Default Microsoft 365 configuration with no conditional access
- Partners using personal devices for client data
- Shared admin accounts for IT support
- No documented record of SaaS apps holding client data
- Off-boarding processes that miss SaaS access
What it really costs to wait
For accountants, lawyers and consultancies, data is the product. A cyber incident is not a back office failure, it is a client trust failure. The hidden cost is the conversations with every named partner client who needs to hear about it from you, not from the press.
Regulator engagement is sector-specific. The SRA, ICAEW and FCA each have their own breach notification and supervision regimes, and incidents trigger reviews that outlast the IT recovery by months.
Cyber insurance for professional services has tightened. Underwriters now require evidence of MFA, hardened email, supplier assurance and tested incident plans. Without those, claims are challenged and renewals are refused.
A scenario we have seen
Context
A 40-partner law firm with practice areas across commercial property, family and corporate, using a hosted practice management system and Microsoft 365.
Trigger
A partner mailbox is compromised through a phishing email. The attacker monitors a live property completion email thread for two weeks before sending forged bank details to the buyer.
Consequence
1.2m pounds is paid to a fraudulent account. The SRA is notified, the buyer sues, and the firm faces a difficult conversation with its insurer about what was and was not in place.
With DefendVista
DefendVista programmes enforce MFA on all mailboxes, deploy impersonation protection on email, and require out-of-band verification of any banking details on transactions, the controls that block exactly this attack pattern.
What good looks like 90 days in
- Client data protected by MFA, encryption and clear access boundaries
- Email hardened against impersonation and business email compromise
- Supplier and outsource arrangements assured against your obligations
- Regulator notification process rehearsed and timed
- Cyber Essentials certificate carried as a visible client trust signal
The standards and obligations in play
Regulatory expectations
SRA, ICAEW and equivalent bodies expect proportionate cyber and data protection controls.
Client due diligence
Major clients now run detailed security questionnaires and audits.
UK GDPR
Client personal data is in scope and often special category.
Cyber Essentials
Common baseline for tenders and insurance.
What good looks like in professional services
Hardened cloud tenant
Conditional access, MFA, modern auth and Defender for Office configured to NCSC guidance.
Identity governance
Joiner-mover-leaver process that includes every SaaS app.
Data classification
Simple, usable classification for client matters and supporting controls.
Endpoint management
Managed devices for everyone handling client data, including partners.
Finance controls
Multi-channel verification of any bank or supplier change.
Tested incident plan
Plan that covers regulatory, client and PR communications, rehearsed annually.
Services that fit professional services
Cyber Essentials Support
Pass Cyber Essentials and Cyber Essentials Plus the first time, without the paperwork pain.
Learn more →Virtual CISO Services
Senior security leadership, fractional cost, zero recruitment risk.
Learn more →Incident Response Planning
Know exactly what to do in the first hour. Test it before you need it.
Learn more →GDPR and Compliance Support
Practical UK GDPR compliance that holds up under regulator scrutiny.
Learn more →What professional services leaders ask us
What is the biggest risk for a professional services firm right now?+
Business email compromise. It is the highest-frequency, highest-loss event we see in this sector.
Are the Microsoft 365 defaults enough?+
No. The defaults are a starting point. Conditional access, modern auth enforcement and proper logging all need configuration.
How do we satisfy client security questionnaires?+
We help you build a reusable evidence pack that answers 80 percent of common questions. Most firms see a dramatic drop in tender effort within a quarter.
Can a vCISO attend client meetings?+
Yes. For major clients and regulator interactions, having a senior security voice in the room is valuable.
More for professional services leaders
Threats
The Most Common Cyber Attacks Affecting UK SMEs
What we actually see hitting UK SMEs week by week, and the controls that stop each one.
Read more →Compliance
GDPR and Cyber Security: What Every Business Owner Should Know
How UK GDPR and cyber security overlap, what the ICO actually expects, and the controls that satisfy both at once.
Read more →Insurance
How Cyber Insurance Requirements Are Changing in 2026
What UK insurers now expect SMEs to have in place, and how to renew without unpleasant surprises.
Read more →Free tool
Cyber Readiness Assessment
Get a personalised risk score in two minutes.
Read more →Free tool
Breach Cost Calculator
Model the financial impact of an incident for your business.
Read more →Talk to a specialist who understands professional services.
Book a free 30-minute consultation. No sales pitch, no obligation. Just clear answers about where your business is exposed and what to do first.