Debra Cairns
As legal firms continue to digitise their operations, the risks to client confidentiality and organisational integrity are greater than ever.
In a sector where trust, reputation and data security are critical, a single cyber breach can have far-reaching consequences beyond the initial disruption or financial loss.
While insider threats remain a significant concern, recent legal cases highlight that the most common cyber attacks are external.
From ransomware and data theft to email compromise and extortion attempts, attackers are constantly evolving their strategies to exploit even the most well-established businesses.
In this article, we will discuss three high-profile incidents affecting UK-based law firms, exploring the most common methods used by attackers, the impact on those involved and, most importantly, how your firm can strengthen its defences to avoid similar incidents.
Case 1: Allen & Overy
Type of attack: Ransomware
The first case we will explore involves Allen & Overy, one of the UK’s most prominent ‘magic circle’ law firms. In November 2023, the firm confirmed it had fallen victim to a ransomware attack affecting a ‘small number’ of its storage servers.
The incident, while limited in technical scope, quickly drew attention due to the nature of the threat and the high-profile status of the firm.
Although there was no initial evidence of data exfiltration, ransomware group LockBit reportedly claimed responsibility for the breach and threatened to publish stolen data, escalating concerns over the incident.
The firm responded swiftly, launching a thorough investigation supported by third-party cyber experts to manage forensics, remediation and client communications. The incident underlined how even well-resourced global organisations with strong reputations are not immune to sophisticated cyber threats.
While the exact entry point for the malware has not been made public, attacks of this nature are commonly initiated through phishing emails, compromised login credentials or the exploitation of unpatched software vulnerabilities. These are among the most common cyber attacks vectors affecting the legal sector.
Once access is gained, attackers typically encrypt critical files and demand payment in exchange for decryption keys, often coupled with extortion threats involving stolen data, as in this case.
This case highlights the legal sector’s particular vulnerability to ransomware. Law firms are attractive targets due to the sensitive nature of the information they hold, the business-critical need to maintain uninterrupted service, and their reliance on external IT service providers.
Effective data loss protection measures would include:
- Real-time monitoring to detect suspicious or anomalous behaviours before ransomware encryption can occur
- Endpoint Detection and Response (EDR) tools to contain threats at the device level
- A well-documented and rehearsed ransomware response plan to guide swift, coordinated action
- Regular, secured backups with offsite or cloud-based storage to ensure recoverability
- Vulnerability management to apply critical patches and close known security gaps promptly
Case 2: Ward Hadaway
Type of attack: Data theft and extortion
Our second case involves Ward Hadaway, a top 100 UK law firm operating across the North of England. In 2022, the firm was targeted in a cyber attack that led to unauthorised access to part of its internal network. The attacker claimed to have downloaded confidential documents and issued a blackmail demand, threatening to publish the data unless a ransom was paid in Bitcoin.
The ransom demand began at $3 million (£2.23 million), doubling to $6 million (£4.46 million) if payment was not received within a week. This method, known as double extortion, applies additional pressure on victims by not only encrypting systems but also
threatening public exposure of stolen data, amplifying legal, financial and reputational consequences.
Ward Hadaway responded rapidly, containing the breach and launching a full-scale investigation alongside external forensic experts. The firm notified the Information Commissioner’s Office (ICO), the Solicitors Regulation Authority (SRA), and law enforcement.
The firm also obtained an injunction from the High Court against ‘persons unknown’ to prevent use or publication of the stolen material, asserting a strong claim for breach of confidence under the Computer Misuse Act 1990.
Justice Johnson, who granted the injunction, emphasised the sensitivity of the material held by the firm, which includes medical reports and personal data linked to cases such as clinical negligence and Court of Protection proceedings.
Although the firm stated that its file management system was unaffected and that operations continued without disruption, the incident underscored the critical importance of proactive cyber security and rapid response.
This case reinforces the growing threat to law firms from cybercriminals seeking to exploit their access to confidential, high-value data. It also illustrates how attackers increasingly rely on anonymity and cryptocurrency to evade detection and complicate legal recourse.
Effective data loss prevention and incident response measures include:
- Data Loss Prevention (DLP) tools to flag and block unauthorised file transfers
- Endpoint monitoring to detect suspicious behaviours such as mass file access or cloud uploads
- Multi-factor authentication (MFA) and strict identity and access controls
- Security Information and Event Management (SIEM) systems for real-time threat detection and log analysis
- Encryption of sensitive files, ensuring that even stolen data remains unreadable without authorised decryption
Case 3: DPP Law
Type of attack: Email compromise and data leak
Our final case involves DPP Law, a Merseyside-based firm that specialises in criminal law and claims against the police. In 2022, the firm suffered a serious cyber attack that led to the theft of over 32GB of client data, including court bundles, police bodycam footage and other highly sensitive material, some of which later appeared on the dark web.
The attack began when a rarely used administrator account associated with an out-of-date case management system was compromised via a remote desktop connection. The firm initially experienced email server failure and network access issues, which were later linked to a ransomware attack. However, no ransom demand was issued, and the true scope of the breach was only revealed when the National Crime Agency informed DPP that stolen data had been published online.
The ICO investigation found significant flaws in DPP’s security controls, including a failure to implement multi-factor authentication, properly assess third-party IT risks or restrict admin-level access. Critically, DPP delayed reporting the breach for 43 days, well beyond the 72-hour legal window, due to a misjudgement over whether the incident qualified as a personal data breach.
As a result, the firm was fined £60,000 in early 2024. The ICO stated that the case should act as a warning to all organisations that data protection is a legal obligation, not an optional safeguard. DPP is appealing the decision but has since migrated its systems to a new provider and begun implementing stronger security controls.
This case demonstrates how legacy systems, poor oversight of third-party IT providers and weak access controls can result in damaging breaches, particularly for legal practices dealing with sensitive client information.
Effective data loss protection measures would include:
- Multi-factor authentication (MFA) as a mandatory control across all accounts
- Email filtering and anti-phishing tools to block malicious links and attachments
- Dark web monitoring to detect exposed credentials
- Ongoing security training to help employees recognise phishing attempts
- Role-based access controls to limit data exposure
How can legal firms detect and respond to external cyber threats?
Most common cyber attacks on law firms begin silently, with a malicious email, compromised login or unnoticed system vulnerability. These initial access points may appear to be minor, but if not identified and addressed immediately, they can lead to serious breaches.
Many of these threats can emerge over time. Attackers may quietly observe systems, move laterally across networks or exfiltrate data in small batches to avoid detection. That’s why early identification is critical.
Common indicators of external compromise include:
- Unexpected file encryption or the sudden appearance of ransom notes
- Unusual login activity, such as attempts from foreign IP addresses or outside working hours
- Surges in outbound data transfers, particularly to unrecognised destinations
- Reports from employees of suspicious pop-ups, email attachments or unexplained account changes
- Disabled security tools, deactivated logs or unapproved software installations
To stay ahead of these threats, your firm should invest in continuous monitoring and intelligent alerting systems that detect abnormal behaviour across endpoints, networks and user accounts. These should be backed by a well-defined incident response plan that outlines roles, communication protocols and recovery steps in the event of a breach.
Additionally, threat detection should be supported by:
· Threat intelligence feeds that provide real-time insights on emerging risks
· Network segmentation to prevent attackers from moving freely between systems
· Regular log audits to spot patterns that automated systems might miss
· Simulated attack exercises to test detection and response capabilities under pressure
Your firm must move beyond basic defences. Proactive detection, layered security architecture and well-rehearsed response protocols are essential, not just for safeguarding sensitive data, but also for maintaining client trust and regulatory compliance.
How Net-Defence can help protect your legal firm from cyber threats
At Net-Defence, we understand that the legal sector faces unique challenges when it comes to cyber security. We provide a range of tailored services that support your firm in strengthening its cyber resilience, including:
Cyber Essentials
As an IASME certifying body, we can guide your firm through the entire process of achieving Cyber Essentials or Cyber Essentials Plus, government-backed certifications that demonstrate your commitment to cyber security.
These frameworks help protect against the most common cyber attacks, such as phishing, malware and unauthorised access, providing a strong foundation for further security measures.
Security Operations Centre (SOC)
Our 24/7 Security Operations Centre offers real-time system monitoring, rapid threat detection and immediate incident response. With our team of analysts on hand around the clock, your firm can detect, analyse and contain cyber threats as they happen, minimising potential damage and downtime.
Cyber security & resilience bundles
Designed with legal firms in mind, our bundled services combine essential certifications like Cyber Essentials with IASME Cyber Assurance, giving you layered protection across people, processes, and technology.
These cost-effective packages are ideal for firms seeking practical support with limited in-house IT or cyber experience.
Cyber Risk Assurance
Using a risk-based approach aligned with the IASME Cyber Assurance standard, we help legal practices identify vulnerabilities, strengthen controls and demonstrate accountability.
From risk assessments to policy reviews, we work with you to build a security posture that aligns with your operational needs and compliance obligations.
ISO 27001 certification
For firms looking to formalise their approach to information security, we provide hands-on support in implementing ISO 27001, the globally recognised standard for Information Security Management Systems (ISMS).
Achieving certification not only enhances your security, but also strengthens your standing with clients, regulators and stakeholders.
Phishing simulations & compliance testing
Human error remains a leading cause of breaches. Our phishing simulations test employee responses to realistic attack scenarios, helping to identify weak points and raise awareness.
Combined with compliance testing, we make sure your team is trained, alert and ready to respond to evolving threats.
CIS Benchmarking & PCI DSS
We help you harden your systems against attack by aligning with CIS benchmarks, industry best practices for securing cloud environments, servers and networks.
If your firm processes or stores payment data, we also provide guidance and auditing support for PCI DSS compliance to safeguard client payment information.
Ready to secure your practice? Get in touch today and discover how we can help your firm stay protected in a fast-changing threat landscape.
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