What is a zero-click attack?

As noted in the definition, the key distinction is that zero-click attacks require no user interaction whatsoever.

Traditional phishing and malware campaigns rely on social engineering. The attacker has to persuade the victim to do something: click a link, open a malicious attachment, enable macros, or install a trojanized app. The malicious code usually runs only after the user opens a booby-trapped file (like a Word document or PDF), which means classic defenses such as antivirus signatures, sandboxes, email filters, and users trained to recognize suspicious attachments have a chance to detect or block the threat.  

Zero-click attacks remove that step entirely. Instead of targeting user behavior and the application layer, they exploit protocol-level vulnerabilities and automatic parsing in messaging apps, communication protocols, or system services. Content is processed silently in the background by parsing engines, protocol handlers, or validation logic, and the exploit triggers without the user doing anything or even noticing.

Another key difference is user awareness. With phishing, training users and filtering emails can significantly reduce risk. With zero-click attacks, even a highly aware user may have no opportunity to prevent compromise because the attack happens without any visible prompt, click, or file opening.

Although specific exploits differ, most zero-click attacks follow a similar pattern. At a high level, they move through three main stages:

1. Identifying the target vulnerability

In most cases, the attacker starts by finding a zero-day vulnerability in a messaging, email, calling app, or another service that receives data from untrusted sources. These apps constantly parse content in the background (messages, images, calls, notifications), which makes them attractive targets.

2. Crafting and delivering the malicious payload

The attacker then crafts a malicious data payload, for example, a specially formed text message, image, email, or network packet, that triggers the vulnerability during this automatic parsing. When the victim's device receives and processes this data, the bug is exploited, and the attacker's code runs on the device.

3. Gaining and hiding control of the device

Once the exploit succeeds, the attacker can often gain extensive control: reading or modifying messages, accessing files, tracking location, activating the microphone or camera, or installing additional spyware. Because zero-click attacks abuse low-level parsing and often clean up after themselves, they tend to leave few traces, making them very difficult to detect and attribute.

Real-world zero-click attacks have been seen in several high-profile spyware campaigns. 

One of the most widely reported is NSO Group's Pegasus spyware, which used a zero-click iMessage exploit known as FORCEDENTRY to infect iPhones simply by sending a specially crafted message, no taps or clicks required. 

WhatsApp has also been targeted multiple times. In the 2019 Pegasus case, attackers exploited a flaw in WhatsApp's call handling so that a missed call could silently install spyware on the device.

More recently, commercial spyware like Paragon's Graphite and other tools have abused zero-click vulnerabilities in messaging apps to compromise journalists, activists, and civil society members. 

New zero-click campaigns continue to appear. In 2025, security researchers documented "Landfall" spyware that infected Samsung phones via malicious image files sent over WhatsApp, exploiting a zero-day in the phone's image processing library and running without any user interaction.

You can't fully eliminate the risk of zero-click attacks, but you can significantly reduce their impact by hardening systems and improving detection and response. Key measures include:

1. Keep everything patched and updated
   Apply OS, app, and firmware updates as soon as they're available, especially for messaging, email, and communication apps that parse untrusted data.
2. Use a multi-layered security architecture
   Combine endpoint protection, mobile device management (MDM), network segmentation, secure configurations, and least-privilege access instead of relying on a single tool.
3. Deploy advanced monitoring and detection
   Use intrusion detection systems (IDS/IPS), EDR/XDR, and behavioral analytics to spot suspicious activity on devices and networks, even when there's no obvious "phishing email" to point to.
4. Have an incident response plan
   Define clear procedures for isolating devices, collecting logs, performing forensics, and restoring from clean backups when a compromise is suspected.
5. Run audits, tests, and simulations
   Regular security audits, penetration tests, and tabletop exercises help uncover weak points and improve overall resilience.
6. Build a security-focused culture
   Train employees on basic cyber hygiene and why rapid patching, secure device use, and reporting suspicious behavior matter, even if "don't click strange links" isn't enough against zero-clicks.
7. Collaborate and share intelligence
   Participate in industry ISACs or information-sharing groups to stay informed about new vulnerabilities, indicators of compromise, and emerging attack techniques.

Zero-click attacks are hard to detect and give users little chance to react, so the real defense is proactive: strong patching, layered security, continuous monitoring, and an organization-wide focus on security rather than one-off technical fixes.