The Five Cyber-Security Controls Every Accounting Firm Needs

Accounting firms are a prime target for cybercriminals, handling sensitive financial data, dealing with high-value transactions, and having the trust of their clients. That combination makes you valuable to attackers – and vulnerable, if your security’s not up to scratch.

The good news is that the vast majority of cyberattacks are opportunistic rather than sophisticated. They rely on weak passwords, untrained staff, and systems with obvious gaps. Close those gaps and you significantly reduce your risk. The five controls below are not theoretical best practice – they are the practical measures that can prevent incidents in firms like yours.

1. Multi-factor authentication

Multi-factor authentication (MFA), adds an extra layer of defence to your systems and should be utilised across critical access points – i.e. any point where you're accessing sensitive data via an online service. This includes email, tax software, and everywhere your client data is stored.

MFA is one of the most effective security measures you can take, with some studies suggesting it can prevent more than 99% of attacks. Hackers may gain access to your passwords, but it is much harder for them to simultaneously intercept authentication codes. Particularly effective are systems that require biometrics or security keys. Least effective are SMS or email-based MFA, which are more vulnerable to interception – leading some experts to suggest the security factor of those kinds of MFA only increase security by 30 - 50%. However, that's still a significant boost compared to password-only protection.

2. Email authentication and filtering

Phishing emails – messages designed to trick you into handing over login credentials or click malicious links – are one of the most common entry points for cyberattacks on accounting firms, and they're getting harder to spot. Modern phishing attempts can convincingly mimic trusted contacts, HMRC, or even your own colleagues.

The first line of defence is technical: email authentication protocols and advanced filtering work behind the scenes to verify that emails come from legitimate sources and screen out suspicious content before it reaches anyone's inbox. Ask your IT provider whether these are properly configured – many smaller firms find they aren't.

But technology alone won't catch everything. A well-crafted phishing email will occasionally get through, which is why your second line of defence is a team that knows what to look for.

3. Security awareness training

Untrained staff are an attacker’s best accomplices. They click phishing links, download malware, reuse passwords, share credentials, leave systems unlocked, and don't report suspicious activity. Attackers often target specific employees with carefully crafted phishing emails – a technique known as spear phishing – precisely because people are far easier to compromise than technology.

Your best defence is ongoing security training, and the most effective form is simulated phishing attacks. These involve sending your team realistic but fake phishing emails to see who clicks on the links, and then using the results to target training where it's most needed. If it sounds sneaky, remind yourself it’s far better to identify vulnerabilities internally than to discover them after a real attack.

Security awareness training is increasingly a compliance requirement, but more than that it shores up the human foundations of your security position and demonstrates to clients that you take your responsibility for their data seriously. Also unlike most security controls, it gets more effective over time.

4. Regularly tested backups

If your server went up in flames, would your immediate response be total panic or mere annoyance? Accountancy firms with backups that are regularly tested and stored separately from their primary systems would face a short disruption before resuming work. For everyone else, the outage could be catastrophic: prolonged downtime, data loss, or worse – a cyberattack where data isn't just lost but stolen or held hostage.

Best practice is the 3-2-1 rule: three copies of your data, on two different types of storage, with one stored offsite or in the cloud, completely separate from your primary environment, and therefore out of reach to anyone who gains access to your network.

Backups also need to be tested regularly. An untested backup is a little like an unread insurance policy – you assume it'll protect you until the moment you actually need it. Hosted desktop providers automate this entire process, with backups running continuously, stored separately, and tested as a matter of routine.

5. Access controls

Limiting access to sensitive data is a surefire way to limit access opportunities for hackers. Rather than giving your entire staff access to everything, limit access and privileges by role. That way, if an attacker gets through, they can't instantly access everything in your network.

This principle – known as 'least privilege' – means a member of staff processing payroll has no reason to access client tax records, and a client portal login has no route into your internal systems. If you picture your network as a maze of rooms, least privilege determines who has which keys.

Virtual desktop infrastructure makes this significantly easier to manage, with all access, permissions and privileges controlled from a single centralised console. A specialist accountancy provider will know which roles typically require which permissions, how to structure access around the way a practice actually works, and how to spot anomalies — and when a staff member leaves or changes role, access can be revoked immediately and comprehensively.

Protect your systems with the right partner

None of these controls are beyond the reach of a small or mid-sized accountancy firm – but implementing and maintaining them consistently is easier with the right infrastructure and the right partner. A hosted desktop solution handles the heaviest lifting: automating backups, centralising access controls, and enforcing MFA across your entire environment as standard.

What makes the difference, though, isn't just the technology. It's working with a provider who understands the specific risks facing accountancy firms – the data you hold, the clients you serve, and the compliance landscape you operate in. If you'd like to talk through what that looks like in practice, get in touch.

If you'd like to talk through what that looks like in practice, get in touch at hello@cloud2me.co.uk or book a meeting here.