What Is Vishing?

How Vishing Works: Techniques and Tactics 

Vishing attacks are becoming increasingly sophisticated, leveraging both technology and social engineering to exploit human vulnerabilities. Below are some of the most common techniques and tactics used by cybercriminals to carry out vishing attacks:

Caller ID Spoofing 

Attackers manipulate telecommunication systems to falsify the caller ID information, making it appear as though the call is coming from a trusted source, such as a bank, government agency, or even a colleague. This tactic lowers the target's defenses by lending an air of credibility to the interaction. As a result, traditional authentication methods tied to caller ID become less reliable, emphasizing the need for more advanced identity verification measures.

Pretexting 

In pretexting, the attacker fabricates a believable scenario, or “pretext,” to convince the target to reveal sensitive information. This could be a fake bank fraud alert or a supposed customer service call requiring account verification. The success of pretexting relies heavily on the attacker’s ability to create a sense of urgency or authority, prompting the victim to act without thoroughly questioning the situation. AI-driven behavior analysis can help identify these social engineering cues before they escalate into full-blown breaches.

VoIP Exploitation 

Voice over Internet Protocol (VoIP) systems have made it easier and cheaper for attackers to make high volumes of calls from anywhere in the world. VoIP services are often less secure than traditional phone lines, making them a prime target for cybercriminals to mask their identity and location. Attackers can use artificial intelligence to automate and scale these operations, increasing the speed and reach of their campaigns. Securing VoIP communications is key to reducing the attack surface in vishing incidents.

Interactive Voice Response (IVR) Attacks 

Interactive voice response (IVR) systems—automated systems that interact with users via voice or keypad inputs—are commonly used by companies for everything from customer service to secure account access. Vishing attacks can target these systems by tricking users into entering sensitive information, such as PINs or passwords, via a compromised or fraudulent IVR interface. Advanced threat detection mechanisms can monitor for unusual patterns in IVR interactions to help identify and mitigate these threats in real-time.

AI-Powered Phishing Attacks

Artificial intelligence (AI) is increasingly being weaponized in the world of cyberattacks, enabling more sophisticated techniques that can deceive even the most vigilant users. When it comes to phishing, AI amplifies attackers' ability to scale, personalize, and manipulate their targets, making vishing more dangerous than ever before.

Voice Cloning

AI-powered voice cloning has become a game changer for vishing attacks. Cybercriminals can now replicate the voice of a trusted individual, such as a company executive or family member, by using just a few minutes of recorded audio. With this technology, attackers can make their vishing attempts far more convincing, tricking victims into divulging sensitive information or authorizing fraudulent transactions.

Deepfake Video Calls

Beyond simple voice manipulation, AI can also create deepfake video calls where attackers impersonate someone in real time. These video-based vishing attacks are especially effective in remote work environments, where visual cues during virtual meetings are often relied upon for trust. By mimicking the appearance and voice of a known individual, attackers can orchestrate highly convincing social engineering schemes.

Robocalls

AI-driven robocalls have evolved from simple automated messages to dynamic interactions that mimic human conversation. Using natural language processing (NLP), these calls can respond intelligently to victims' input, making the interaction feel more authentic. This allows attackers to scale their vishing attempts, reaching hundreds or thousands of potential victims in a short period.

AI Data Mining for Targeted Vishing

AI can sift through vast amounts of publicly available data, such as social media profiles, company websites, and leaked databases, to create highly targeted vishing attacks. By building detailed profiles of potential victims, cybercriminals can craft personalized vishing attempts that seem credible and relevant, increasing the likelihood of success. The result is a more focused attack that leverages the victim's specific circumstances or relationships. 

As AI continues to evolve, so too do the threats posed by these advanced vishing techniques. Organizations must stay ahead by adopting AI-powered security solutions that can detect and counteract these emerging risks.

By understanding these techniques, organizations can better anticipate and mitigate the risks associated with vishing, especially as criminals continue to evolve their methods.

Why Is Vishing a Growing Threat?

Vishing is seeing more and more use due to the increasing sophistication of cybercriminals as well as the widespread reliance on mobile communication. Attackers are leveraging advanced social engineering tactics to exploit human vulnerability, often bypassing traditional security measures. With people more connected than ever, especially with the rise of remote work, fraudsters are finding new opportunities to manipulate individuals into revealing sensitive information over the phone. 

Moreover, the accessibility of personal data on the web has empowered attackers to craft highly convincing, targeted vishing attempts. Cybercriminals can now easily gather enough personal details to simulate legitimacy, making it harder for even the most vigilant individuals to detect a scam. As AI technology progresses, attackers themselves are using machine learning and voice synthesis tools to create even more realistic impersonations of trusted entities, further amplifying the challenge for organizations and individuals alike. In fact, over the past year, AI-driven phishing attacks (including vishing) have increased 60%.

Real-World Examples

Sophisticated vishing campaigns are becoming popular worldwide, with cybercriminals using psychology and technology to defraud even savvy victims of millions of dollars. For example, South Korea has experienced a surge in vishing attacks, including a case in August 2022 where a doctor lost $3 million in cash, insurance, stocks, and cryptocurrency to criminals. In this case, scammers impersonated regional law enforcement officials in South Korea; however, ThreatLabz observed (and thwarted) a vishing attack very close to home in 2023.

In another example, a finance employee in Hong Kong paid $25 million after a video call with deepfake ‘chief financial officer’ on a video conference call. The actor tricked the employee into attending a video call with who he thought were several other members of staff but were actually deepfake recreations.

In the summer of 2023, attackers impersonated Zscaler’s own CEO, Jay Chaudhry, in a vishing attack using AI technology. It unfolded like this:

1. The attacker called a Zscaler employee on WhatsApp.
2. Using AI-generated voice cloning to simulate Jay’s voice, the attacker established communication, and then quickly hung up to avoid prolonged interaction and potential exposure.
3. The attacker immediately followed up with a text message—posing as Jay—claiming to have “poor network coverage.”
4. In a WhatsApp text message, the attacker instructed the Zscaler employee to purchase gift cards for a certain amount.
5. The employee found this suspicious and immediately reported it to the security team.
6. ThreatLabz researchers investigated and found out it was part of a widespread campaign targeting several tech companies.

To effectively combat this growing threat, cybersecurity must evolve beyond traditional defenses. AI-powered systems that can detect suspicious patterns in real-time and assess risk on a granular level are becoming essential. By integrating advanced risk management capabilities, organizations can better protect themselves and their employees from falling victim to increasingly sophisticated vishing schemes.

Common Vishing Scenarios

Vishing attacks come in many forms, each designed to exploit trust and convince victims to share sensitive information. Here are some of the most common tactics used by cybercriminals: 

• Bank fraud scams: Callers pose as bank representatives, claiming your account has been compromised. They pressure you into providing personal details or even transferring funds to a "secure" account.
• Tech support scams: Fraudsters impersonate tech support from reputable companies, warning of malware on your device and requesting remote access to "fix" the issue, which is actually a ploy to steal data or install malicious software.
• IRS/tax scams: Attackers claim to be from the IRS or tax authorities, threatening arrest or legal action unless you pay an outstanding tax bill—often via untraceable methods like gift cards or wire transfers.
• CEO fraud (Business email compromise): Cybercriminals target employees by impersonating senior executives, instructing them to make urgent wire transfers or disclose confidential company information, often under the guise of a time-sensitive emergency.

Vishing vs. Phishing vs. Smishing

While all three—vishing, phishing, and smishing—are forms of social engineering attacks designed to manipulate victims into divulging sensitive information, they differ primarily in their delivery methods and the specific tactics used to exploit human trust. Understanding these distinctions is crucial for developing a robust, proactive security strategy, especially as cybercriminals continue to evolve their techniques. 

Phishing

Arguably the most well-known of the three, phishing typically involves fraudulent emails that impersonate legitimate entities, such as businesses, government agencies, or trusted individuals. The goal of phishing attacks is usually to steal login credentials, financial information, or other sensitive data. 

Phishing often leverages a sense of urgency or fear, prompting the victim to click on malicious links or download infected attachments. As email remains a primary communication tool in both personal and professional contexts, phishing attacks have a broad reach and can be devastating if not caught early.

Smishing

Smishing is a more recent evolution of phishing that targets individuals through SMS or text messages. Like phishing emails, smishing messages often appear to come from trusted sources—such as banks, delivery services, or even coworkers—and typically include a malicious link or prompt to share sensitive details. 

This method is particularly dangerous because it capitalizes on the immediacy and casual nature of text messaging, where users are more likely to respond quickly and without suspicion. Given the ubiquity of smartphones and the increasing reliance on SMS-based communications, smishing attacks have been rising rapidly.

Vishing

As defined earlier in this article, vishing uses voice communication, typically via phone calls, to manipulate victims. Attackers may impersonate, whether through text or AI voice cloning technology, authority figures such as tax officials, tech support representatives, or even family members in distress. 

Their goal is often the same as in phishing and smishing: to extract sensitive information, such as passwords or credit card numbers, or to convince the victim to take specific actions, like transferring funds. Vishing has the added layer of directly exploiting human psychology through real-time conversation, making it harder for victims to pause and critically assess the situation.

Key Differences in Attack Vectors and Tactics

Phishing operates predominantly through email, making it a written form of deception. Attackers often include well-crafted email templates and logos to mimic legitimate organizations. These emails usually contain malicious links or attachments that exploit vulnerabilities in the recipient’s system once clicked or downloaded.

Smishing takes advantage of SMS, a medium known for its brevity and urgency. The messages often contain shortened URLs to disguise malicious links, and users may be more inclined to trust texts due to the personal nature of mobile devices.

Vishing relies on voice interaction, which can add a layer of pressure or emotional manipulation that is not as easily conveyed through text. Attackers may use tactics like "spoofing" phone numbers to make the call appear as though it’s coming from a legitimate source, such as a government agency or a known institution.

How to Protect Yourself and Your Organization from Vishing

Vishing attacks are growing in sophistication, but there are clear steps your organization can take to mitigate the risk. Implementing the right strategies can help safeguard both personal and corporate information from voice-based phishing threats.

Security Awareness Training 

Regularly educating employees about vishing tactics is critical. Comprehensive training programs can teach staff to recognize red flags like unsolicited calls, pressure tactics, or requests for sensitive information. Awareness is the first line of defense in preventing successful attacks.

Caller Authentication Procedures 

Implementing strict caller authentication procedures can reduce the likelihood of falling victim to vishing. Ensure that employees follow verification protocols, such as calling back official numbers and using multifactor authentication (MFA) to confirm the identity of the caller before sharing any sensitive information.

Use of Anti-Spam Technology 

Leverage AI-driven anti-spam and call-filtering technologies to block suspicious or unsolicited calls before they reach your team. These tools can analyze patterns and detect potential phishing attempts, providing an added layer of protection against vishing attacks.

Incident Response Plans 

Having a robust incident response plan in place is essential for minimizing the damage if a vishing attack slips through. Ensure your organization has clear protocols for reporting suspicious calls and investigating potential breaches, so that swift action can be taken to contain any threats.

AI Security and Threat Intelligence 

Incorporating AI-powered security solutions can enhance your organization’s ability to detect and respond to vishing campaigns in real-time. By leveraging threat intelligence, these systems can identify emerging vishing methods, enabling proactive defenses that evolve as the threat landscape changes.

Looking Ahead: The Importance of a Layered Zero Trust Approach 

Phishing, smishing, and vishing all exploit the weakest link in cybersecurity—human behavior. To effectively combat these threats, organizations need to adopt a zero trust approach, assuming that no communication, platform, or user is inherently trustworthy. 

This paradigm shift requires a multi-layered defense strategy that integrates AI-powered monitoring, continuous authentication, and endpoint protection. By combining user education with cutting-edge technology, organizations can stay ahead of attackers and significantly reduce the risk of falling victim to social engineering. 

As these malicious tactics evolve, so too must defenses—ensuring that every email, text, and phone call is scrutinized with the same level of diligence and skepticism. While phishing, smishing, and vishing present distinct challenges, a unified, AI-enhanced security strategy can help mitigate the risks posed by all three, fostering a more resilient and secure digital environment.

How Zscaler Can Help

To effectively defend against the evolving threat landscape, organizations need to integrate advanced phishing prevention controls into zero trust strategies. At the forefront of this defense strategy is the Zscaler Zero Trust Exchange™, built on a robust zero trust architecture.

Taking a comprehensive approach to cybersecurity, the Zero Trust Exchange effectively thwarts both conventional and AI-driven phishing attacks at multiple stages of the attack chain with:

AI-Powered Phishing and C2 Prevention

Zscaler AI models detect known and patient-zero phishing sites to prevent credential theft and browser exploitation, as well as analyze traffic patterns, behavior, and malware to detect never-before-seen command-and-control (C2) infrastructure in real time.

File-Based AI Sandbox Defense 

The AI-powered inline Zscaler Sandbox instantly detects malicious files while keeping employees productive.Our AI Instant Verdict technology instantly identifies, quarantines, and prevents high-confidence malicious files—including zero-day threats— while removing the need to wait for analysis on these files.

AI to Block Web Threats 

AI-powered Zscaler Browser Isolation blocks zero-day threats while ensuring employees can access the right sites to do their jobs. Our AI Smart Isolation can identify when a site may be risky and open it in isolation for the user—safely streaming the site as pixels in a secure, containerized environment.

Want to see Zscaler's powerful phishing defense in action? Schedule a custom demo with one of our experts and let them show you how Zscaler protects against the most advanced AI-based threats.