Exploit kits are sophisticated tools that allow cybercriminals to exploit software vulnerabilities. They are a key method of spreading malware across the Internet, affecting individuals and organizations alike.
What Is an Exploit Kit?
An exploit kit, or an exploit pack, is a software package that automatically scans for security vulnerabilities on the target device and uses those vulnerabilities to deliver malware. Exploit kits are typically hosted on malicious or compromised websites and activate when a user visits such sites. Their primary function is to facilitate the mass distribution of malware without requiring complex technical skills from the user, making them a popular tool among attackers. These kits are highly adaptable and frequently updated to include new exploits when vulnerabilities are discovered. Exploit kits are typically built and maintained by experienced cybercriminals and sold or rented on the dark web to other attackers.
How Does an Exploit Kit Work?
Exploit kits are collections of pre-written code that include the following components:
- Landing page. This initial script runs when a victim visits a malicious or compromised website. It is responsible for determining the web browser version, installed plugins, and security settings of the visitor's system.
- Exploit engine. This core component includes the logic and algorithms needed to select and execute exploits based on the data gathered by the landing page. It can handle multiple exploits tailored for different vulnerabilities and is designed to be modular to easily add new exploits as they become available.
- Payload delivery system. Once an exploit successfully compromises a system, this component delivers the final payload, such as ransomware, spyware, or a banking Trojan. The payload is often encrypted to avoid detection by network monitoring tools and antivirus software.
- Statistical tracking. Many exploit kits include a backend dashboard that provides statistics on the number of infections, success rates of different exploits, and the geographic distribution of victims. This data helps the criminals optimize their attacks and gauge their success.
Exploit Kit Infection Stages
The operation of an exploit kit is a multi-stage process involving various techniques to breach a device's defenses. Here are the steps involved in an exploit kit infection:
- Initial contact. The infection chain usually starts when a user is lured to a compromised website, clicks on a malicious advertisement, or opens a deceptive link from an email or social media message. These initial attack vectors are designed to be innocuous, blending seamlessly with legitimate content to increase the likelihood of success.
- Redirection. Once initial contact is made, the exploit kit redirects the user to a controlled landing page. This page is typically hosted on a server that appears benign or is hijacked for malicious purposes. The landing page serves as the gateway for further actions and is crucial for determining the vulnerability profile of the visiting device.
- Preconditioning. Before deploying malicious payloads, the exploit kit may perform several checks to ensure the environment is suitable for infection. This inspection might include detecting the operating system, browser type, installed software versions, and security measures like antivirus programs. The kit uses this information to tailor its attack to the specific vulnerabilities present on the device.
- Exploit delivery. With the target's environment assessed, the exploit kit delivers the code to leverage one or more vulnerabilities detected during the preconditioning stage. These exploits are often packaged in small, efficient modules that can quickly execute without detection. The exploits range from buffer overflows to sophisticated attacks such as use-after-free vulnerabilities.
- Malware installation. Successful exploitation results in the deployment of malware. The type of malware varies based on the attacker's objectives and may include ransomware, spyware, data stealers, or remote access tools. The malware is typically executed silently to avoid alerting the user, embedding itself within the system to ensure persistence and evade removal.
- Post-exploitation. After installing the malware, the exploit kit may perform additional tasks, such as establishing communication with a command-and-control server. This extra step allows the attacker to control the compromised device remotely, upload additional malicious software, or exfiltrate stolen data. The exploit kit can also attempt to cover its tracks by clearing logs or using encryption to conceal its activities.
Exploit Kit Delivery Mechanisms
Exploit kits primarily use two delivery mechanisms:
- Drive-by downloads. This technique exploits vulnerabilities in a browser or its plugins to install malware without user interaction beyond visiting a compromised website.
- Malvertising. This technique involves attackers placing malicious advertisements on legitimate websites. These ads include scripts that redirect users to the exploit kit's landing page or directly contain exploit code.
Exploit Kit Examples
Several exploit kits have gained notoriety for their widespread use and the sophistication of their attacks:
- Angler exploit kit. This kit was particularly feared for its ability to use zero-day exploits, vulnerabilities unknown to software makers at the time of the attack.
- Blackhole exploit kit. Once the most widespread exploit kit, it was dismantled after its developer was arrested.
- RIG exploit kit. Continuously updated, this kit is known for distributing various malware types, including ransomware and banking Trojans.
- Neutrino exploit kit. This kit is noted for its stealth and effectiveness in delivering payloads like crypto-mining malware.
Types of Vulnerabilities Exploited by Exploit Kits
Exploit kits target a range of system weaknesses to gain unauthorized access:
- Outdated software. Hackers often target systems running outdated or unsupported versions of browsers, Java, Adobe products, and other widely used software.
- Software flaws. Unpatched software vulnerabilities are a goldmine for exploit kits looking for easy entry points.
- Configuration weaknesses. Improperly configured systems and applications provide loopholes that these kits can exploit.
How to Prevent Exploit Kit Attacks?
To protect against exploit kits, follow these cybersecurity best practices.
- Regular software updates. Keeping all system software up to date is crucial as it reduces the number of exploitable entry points.
- Use of security software. Implementing robust antivirus, anti-malware, and intrusion detection systems helps detect and block exploit kits before they can harm.
- Security awareness training. Training can help users identify and avoid threats like phishing and malicious websites.
- Network segmentation. By dividing network resources into distinct zones, organizations can reduce the lateral movement of malware within systems.
- Browser security settings. Proper configuration of browser settings to block unauthorized downloads and restrict access to risky websites is essential for preventing infections.
