Imagine receiving a phone call where the voice sounds exactly like your CEO, matching their accent and cadence. They claim an urgent invoice must be paid immediately to secure a time-sensitive acquisition and ask you to authorise an emergency transfer.
Although the call sounds authentic, it’s not your CEO. Instead, an attacker is using generative AI to clone their voice in real time from a remote location.
This scenario is now a real threat. Phone-based social engineering has advanced quickly, outpacing traditional security controls. To protect your organisation, it’s essential to understand how vishing works today, how attackers operate, and what steps you can take to prevent these attacks.
What is Vishing in Cyber Security?
Vishing, short for voice phishing, is a phone-based attack in which criminals use voice calls to trick individuals into handing over sensitive information, granting unauthorised access or transferring funds.
Vishing leverages AI voice tools to create fraudulent deepfakes. With just one video interview, social post, or podcast, attackers can generate a convincing voice clone. These methods are significantly more effective than traditional vishing, which relied on impersonation and extensive research.
Attackers exploit psychological triggers such as urgency, fear, curiosity, and trust. People are often more likely to trust a familiar voice on the phone than an unverified email.
Vishing Vs Phishing and Smishing
Social engineering attacks typically fall into three categories based on the communication channel:
- Vishing involves voice calls
- Phishing uses email
- Smishing targets victims through text messages or SMS.
Although each method uses a different channel, attackers often combine them in multi-stage operations. For example, a victim may receive a fraudulent text about a locked account, followed by a vishing call from someone offering assistance.
How Common is Vishing?
Vishing has grown rapidly across all sectors, driven by accessible AI tools and inexpensive VoIP infrastructure. Industry research shows social engineering remains a leading initial access vector for corporate breaches, with voice-based attacks increasing sharply each year.
Financial institutions, technology providers, and corporate finance departments are primary targets, but any organisation that handles sensitive data or processes transactions is at risk. Scammers now target help desks, HR managers, and finance executives to bypass technical security controls, rather than focusing solely on individuals’ bank details.
What's The Most Common Tactic in Vishing Attacks?
Scammers combine the authority of the impersonated individual with a manufactured sense of urgency. They create scenarios that pressure victims to act immediately to prevent a disaster or seize an opportunity.
By impersonating high-ranking executives, IT support staff, bank fraud department personnel, or regulatory officials, attackers use their authority to bypass standard procedures. Their goal is to override critical thinking and prompt immediate action, bypassing established protocols.
What's an Example of a Vishing Attack?
A classic corporate example is the IT help desk reset scam.
An attacker calls an employee, claiming to be a senior IT engineer. They state that an urgent security patch is required or that suspicious activity has been detected on the employee’s account.
To proceed, the attacker instructs the employee to visit a fake login portal or provide a multi-factor authentication code sent to their device. Once the code is shared, the attacker gains immediate, authenticated access to the corporate network, bypassing technical controls.
Identifying the Red Flags of a Vishing Call
The primary red flag for a vishing attack is any unsolicited caller requesting sensitive credentials, approval of a push notification, or a bypass of established security procedures.
Legitimate organisations, internal IT teams, and financial providers will not contact you unexpectedly to request your password, MFA token, or a transfer to an unverified account. Any request that violates standard corporate policy should raise immediate concern.
What is One Key Sign of a Vishing Attack?
Be alert to resistance when you request further verification. Legitimate colleagues or vendors will not object if you insist on calling them back using an official, pre-verified company number.
Attackers, however, will try to keep you on the line. They may claim that hanging up will result in immediate system failure, account termination, or disciplinary action.
Additional indicators to watch for include:
- Unsolicited requests for sensitive data, access tokens or financial transfers.
- Caller ID manipulation (number spoofing) designed to look like an internal extension or local bank.
- Voice anomalies such as awkward pauses, unexpected robotic tones or odd responses to interruptions.
- High-pressure tactics designed to make you feel uncomfortable verifying the request.
How To Protect Your Business from Vishing Attacks?
Despite these threats, you can take effective steps to protect yourself and your business from vishing. We recommend the following actions:
Establish clear out-of-band verification protocols.
For all communications, especially those involving finances or access credentials, establish a clear policy for verifying requests. Use a separate, pre-approved communication channel to reduce attackers’ access to your systems.
If a manager requests an urgent payment, inform them you will call back using their official phone number or contact them through internal messaging systems.
Implement multi-factor authentication (MFA)
Ensure your organisation transitions away from legacy MFA methods that are vulnerable to phone-based attacks. One-time passcodes sent via SMS or voice call can be easily obtained by attackers during a vishing attempt.
Adopting FIDO2 hardware keys or domain-bound, phishing-resistant authentication methods significantly reduces the risk of credential theft, even if an employee is deceived during a call.
Deliver continuous security training.
As cyberattack techniques evolve, your awareness and training must also adapt to address the latest threats.
Providing tailored, interactive cybersecurity training helps employees recognise voice manipulation tactics, understand psychological coercion, and gain the confidence to challenge unexpected requests without fear of reprisal.
Evaluate your security posture regularly.
Technical controls should be tested regularly to ensure effectiveness. Conducting penetration tests, maturity assessments, and strategic reviews helps identify technical gaps and process weaknesses before attackers exploit them.
Structured reviews, such as a Cyber MOT, enable organisations to benchmark security maturity, identify access management vulnerabilities, and develop a clear, prioritised improvement roadmap.
Monitor and share intelligence.
Staying ahead of emerging social engineering trends requires active threat intelligence. Subscribing to regular security updates and encouraging staff to report suspicious calls helps your security team adapt defences quickly.
For daily updates on emerging threats, vulnerability alerts, and industry insights, follow our Daily Cyber Briefing to keep your security team informed and prepared for the evolving threat landscape.
Building long-term resilience against vishing
If your company operates from an office, the simplest way to verify requests is to arrange a face-to-face meeting to confirm their legitimacy.
As voice deepfakes and generative AI advance, distinguishing between real and fake communications will become increasingly difficult. Relying only on technical filters is no longer sufficient to protect your organisation from voice-based social engineering.
By implementing strict verification controls, fostering a culture where staff are empowered to double-check unusual requests, and working with experienced security professionals, you can build a resilient defence that protects your people, data, and reputation.
Don’t wait until cyber risks catch up with you. Our team specialises in compromise assessments for acquisitions, SIEM consolidation for acquired companies, and comprehensive monitoring and threat detection for mergers. Get in touch today to learn about our approach to cyber security in mergers and acquisitions to protect your new assets and ensure a smooth, secure integration.
Call us on +44 20 8133 0660 or fill out our contact form and we’ll help you get it sorted.
