Excerpt from ‘Leave No Trace: A Red Teamer's Guide to Zero-Click Exploits’
This article is an excerpt from ‘Leave No Trace: A Red Teamer's Guide to Zero-Click Exploits’
available on Amazon, Google Books and Barnes and Nobles.
What is a Zero-Click Exploit?
In the realm of cybersecurity, a zero-click exploit has evolved into one of the most insidious and effective forms of attack vectors available to cybercriminals. To fully appreciate the scale of the threat they pose, it is vital to understand what exactly constitutes a zero-click exploit.
A zero-click exploit, as the name implies, is a type of cyber attack that does not require any form of interaction from the target. Traditional forms of cyberattacks often rely on a victim clicking on a malicious link or opening a corrupted file. Zero-click exploits, in contrast, can compromise a system invisibly, bypassing any need for the victim's intervention.
How does a Zero-Click Exploit Work?
A zero-click exploit operates by taking advantage of vulnerabilities within a device's software or firmware. These vulnerabilities, often known as 'zero-day vulnerabilities', are flaws in the system that the software's creators are unaware of and, therefore, have not released a patch for. Cybercriminals constantly scour software systems for these unpatched vulnerabilities, and when they discover one, they craft a specialized piece of software or script—known as an exploit—to take advantage of it.
Zero-click exploits often target services designed to automatically process incoming data, such as messaging apps or email clients. For instance, an attacker could send a specially crafted text message or email to a target, and the app's automatic processing of this data could trigger the exploit and compromise the device, all without the user ever needing to open or even see the malicious message.
Why are Zero-Click Exploits Dangerous?
The primary danger of zero-click exploits lies in their stealth and simplicity. They leave minimal traces of their activity, making them exceptionally hard to detect, and the absence of required user interaction removes one of the key defenses against traditional cyber-attacks: user vigilance.
The reduced interaction involved in zero-click attacks means that there are fewer traces of any malicious activity. This, coupled with the fact that zero-day vulnerabilities which cybercriminals can exploit for zero-click attacks are quite rare, makes them highly prized by attackers.
Their covert nature allows them to circumnavigate common forms of cyber defenses. Conventional cybersecurity measures, such as firewalls and antivirus software, might not recognize a zero-click exploit as a threat since they're designed to look for known malware signatures or suspicious behavior patterns. As a zero-click exploit takes advantage of legitimate processes in the system, it often doesn't exhibit behavior that these security measures would flag as malicious.
Zero-click exploits are not a new phenomenon. They have been around for years, but their prevalence has significantly increased with the rise of smartphones and other connected devices. The reliance of individuals and organizations on these devices, coupled with the wealth of personal and professional data they hold, makes them an attractive target for cybercriminals.
The increasing sophistication of threat actors, and the rise of state-sponsored cyberattacks have also contributed to the rise of zero-click exploits. These advanced actors have the resources to invest in finding and exploiting zero-day vulnerabilities, leading to a rise in the number of discovered zero-click exploits.
Understanding zero-click exploits, their operation, and their potential impact is the first step in defending against them. In the subsequent chapters of this book, we will dive deeper into the technical aspects of these threats, exploring real-world instances of zero-click exploits, and offering insights into how red teamers can adapt their methodologies to simulate these attacks and help organizations bolster their defenses.
Real-world Instances of Zero-Click Exploits
In order to gain a more practical perspective on zero-click exploits, it is beneficial to look at real-world examples. Not only do they demonstrate the full scale and potential of such attacks, but they also offer unique insights into the methodologies adopted by the attackers.
The Pegasus Project
Perhaps the most infamous example of a zero-click exploit is the Pegasus spyware developed by the Israeli firm NSO Group. A sophisticated piece of malware capable of infecting both Android and iOS devices, Pegasus was found to be utilizing zero-click exploits to silently infect victims' devices.
The Pegasus spyware was leveraged in several high-profile attacks around the world, including against human rights activists, journalists, and political figures. The zero-click exploits used by Pegasus were found to be delivered through voice calls on messaging apps such as WhatsApp and iMessage. Victims did not even have to answer these calls for their devices to be infected.
The WhatsApp Breach of 2019
In 2019, the popular messaging service WhatsApp experienced a significant breach when a zero-click exploit was used to install spyware on victims' devices. This exploit was triggered by a simple missed call, which allowed attackers to load spyware deep within the device’s software framework.
This incident highlighted the vulnerability of even the most trusted and widely-used apps and demonstrated how zero-click exploits could be utilized to target a large number of users rapidly.
Project Raven
The United Arab Emirates' offensive cyber operations unit, known as Project Raven, reportedly utilized zero-click exploits to conduct widespread surveillance. Using a tool known as Karma, they exploited a flaw in Apple's iMessage app to infiltrate iPhones of activists, diplomats, and foreign leaders, thereby gaining access to sensitive data.
The Anatomy of Zero-Click Exploits
Having examined some instances of zero-click exploits, it is critical to delve deeper into the technical elements of these attacks. This chapter will break down the key components of a zero-click exploit, exploring the process from the initial discovery of a vulnerability to the final execution of the exploit.
Discovering Vulnerabilities
The success of a zero-click exploit heavily depends on finding exploitable vulnerabilities within a system's software or firmware. This process often requires extensive knowledge of software development and reverse engineering, as well as a high level of patience and persistence.
Crafting the Exploit
Once a vulnerability is discovered, the next step involves developing an exploit that can leverage this vulnerability. This process may involve writing custom code, manipulating data inputs, or a combination of both.
Delivering the Exploit
The method of delivering a zero-click exploit can vary depending on the nature of the vulnerability being exploited. For some exploits, a simple email or text message might be enough, while others might require more complex delivery methods.
Bypassing Defenses
An effective zero-click exploit must also be capable of evading the device's defenses. This may involve bypassing or disabling antivirus software, evading intrusion detection systems, or other methods designed to conceal the exploit's activities.
The final stage of a zero-click exploit is the execution of the exploit itself. This could involve anything from installing malware on the device, to exfiltrating data, or even gaining full control over the device's functions.
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