83%. That’s the percentage of organizations that suffered at least one account takeover in the past 12 months, according to the 2024 Abnormal State of Cloud Account Takeover Attacks. Let that number sink in.
Now pair that with another sobering stat: Cyberattacks on accounting firms have surged 300% since 2020. You face a growing yearly threat if you manage sensitive financial data such as tax filings, payroll details, audits, and client PII.
Accounting firms aren’t just financial advisors anymore. They’re data vaults. And threat actors? They’ve upgraded from crowbars to state-sponsored hacking kits.
The 2025 Threat Landscape: Why Financial Firms Are Prime Targets
Attackers prioritize financial gains, and accounting firms strategically position themselves at the nexus of high-value data and high-trust client relationships. From tax returns to payroll files, the information flowing through your systems is a jackpot for cybercriminals.
What’s more, most small to mid-sized firms lack the security infrastructure of big banks, making them soft targets. Maintaining a competitive edge is increasingly crucial as regulatory pressure intensifies and threat actors undergo rapid evolution.
Let’s break down the top 5 cybersecurity threats for accounting firms in 2025, why they’re evolving fast, and what innovative firms are doing to stay ahead.
1. Phishing Goes AI: Why Your Inbox is a War Zone
Phishing is nothing new. What’s changed is precision. In 2025, AI powers phishing attacks with near-perfect grammar, personalized context, and real-time data scraped from public sources. These aren’t the typical emails you receive from a Nigerian prince.
Now, attackers pose IRS agents with accurate client employer identification numbers (EIN) or mimic vendor invoices with surgical accuracy. For accounting firms swimming in compliance documents and vendor interactions, it’s an effortless snare.
This new breed of phishing attacks in 2025 doesn’t just dupe interns. Partners, CFOs, and even IT staff fall for them. All it takes is one click.
If your email security only detects obvious spam, you’re at risk. Layered detection systems, employee training, and active phishing simulations are now basic hygiene for IT security for certified public accountants (CPAs).
2. Ransomware Reloaded: Accounting Firms in the Crosshairs
In 2024, 65% of financial services organizations fell victim to ransomware. What is the average cost of recovery? The average cost of recovery was a staggering $2.73 million. These are flashing sirens for what’s already here.
Ransomware in accounting has gone beyond basic encryption. Attackers steal the data first, then lock systems, and extort again by threatening public exposure. This approach is called a double extortion scheme. Indeed, hackers can easily access client data.
What’s so great about accounting firms? Data with structures. Hackers don’t have to look for things. They know the place where enticing reports are kept. They understand what “QBO_Backup” means. They also see the firm’s tax-season timeline when downtime is most painful.
Endpoint detection, offline backups, and 24/7 monitoring are survival mechanisms for firms that are serious about IT security for accounting firms.
3. Credential Stuffing and Account Takeovers Skyrocket
Reused passwords and poor MFA adoption are becoming increasingly problematic, as 83% of organizations have experienced at least one account takeover. Especially vulnerable are financial firms with remote staff, seasonal workers, or contractors.
Credential stuffing attacks use bots to force logins across tax software, client portals, and accounting platforms. Once in, attackers quietly redirect payments, exfiltrate data, or impersonate users for internal fraud.
What’s scarier? Most of these breaches have been undetected for months.
It’s not just about MFA. Firms need login behavioral monitoring, dark web scanning for leaked credentials, and proactive IT management to shut down risks before they snowball into full-blown accounting data breaches.
4. Third-Party Vendor Risk: The Hidden Backdoor
That cloud-based time-tracking tool you integrated last year? Or that e-signature platform your clients love? Should those vendors experience a breach, it will also affect you.
Cybersecurity risks in finance are silently eliminated by third-party breaches. Attackers exploit the weakest link in the vendor chain. Accounting firms, with dozens of integrations and plug-ins, often lack visibility into these risks.
Cybercriminals are effectively taking advantage of firms that rely on unmanaged tools, unvetted add-ons, or generic admin accounts.
Vet every vendor. Enforce zero trust policies. Invest in third-party risk assessments to prevent association compromise.
5. Data Exposure from Within: Not Every Threat Wears a Hoodie
Sometimes, the most significant cybersecurity threats for accounting firms in 2025 come from the inside. Internal data mishandling, whether from an over-permissioned junior staffer or a simple misclick, contributes significantly to accounting data breaches.
The AICPA has repeatedly flagged insider threats as a growing concern, especially as firms increase remote work and shared cloud access.
Unsecured Dropbox folders, emailed spreadsheets, or the “Final_Final_Client_Return_v6.xls” floating around in a shared drive are all potential security risks. Each is a breach waiting to happen.
Implement strict data governance. Use file-level encryption. And educate your team, as if your future depends on it.
The Smart Play: Partnering with a Security-First IT Firm
You can’t patch your way out of this problem. Accounting firms need a comprehensive strategy, not just software solutions. That’s where firms like Plexus Technology come in with day-to-day, ground-level visibility into what’s happening inside your network.
For over 17 years, Plexus has delivered expert IT support to financial firms across the greater Phoenix area, combining over 35 years of IT expertise. Their team isn’t just on call—they’re on top of it. That means prompt response times, zero-downtime protection, and battle-tested insight that aligns perfectly with how CPAs and financial professionals work.
Don’t Wait for a Breach to Take Cybersecurity Seriously
Here’s the top cybersecurity threats for accounting firms in 2025: they don’t knock. They walk right in through a missed patch or an innocent email click.
In 2025, the firms that are already preparing for a breach and implementing appropriate security measures will prosper.
If you’re ready to protect your data, your clients, and your firm’s reputation, it’s time to schedule a consultation with Plexus Technology. Let’s make your IT work for you, not against you.
