Exploit kits first emerged in 2006 and have since been used as an automated method of malware delivery. Exploit kits are programs that are loaded onto websites that contain exploits for known vulnerabilities. When a visitor lands on a web page that hosts an exploit kit, it performs a scan to determine if certain software vulnerabilities have not been patched. If an unpatched vulnerability is identified, the exploit kit will choose an exploit and will deliver a malware payload with no user interaction required.

Exploit kits became hugely popular with threat actors between 2010 and 2017, and while their use has declined to a fraction of the level seen in 2016 and 2017, they do still pose a threat. There are several exploit kits still being used that are regularly updated with new exploits for known vulnerabilities, and over the past couple of years they have mostly been used to deliver malware loaders that deliver ransomware.

The Fallout exploit kit for example has been used to deliver Maze Locker ransomware, and the Magnitude EK, which was first identified in 2013, is also being used to deliver ransomware, mostly in the Asia Pacific region.

Exploit kits are loaded on legitimate websites that have been compromised, as well as attacker-owned websites, with traffic to the latter often delivered through malicious adverts (malvertising). It is therefore easy to land on a site hosting an exploit kit through general web browsing.

The Magnitude EK is now one of the most extensively used exploit kits which, until recently, was only being used to target Internet Explorer; however, the exploit kit has now been updated and is being used to target Chromium-based web browsers on Windows PCs.

Avast reports that two new exploits have recently been added to the Magnitude EK, one of which targets a vulnerability in Google Chrome – CVE-2021-21224 – and the other targets the Windows kernel memory corruption vulnerability tracked as CVE-2021-31956. The Google Chrome bug is a remote code execution vulnerability, and the Windows bug can be exploited to bypass the Chrome sandbox, allowing an attacker to gain system privileges.

Patches have been released by Google and Microsoft to address both of these flaws; however, the reason why exploit kits are still an effective method of malware distribution is many people delay or ignore software updates. While the Magnitude EK is not believed to be currently exploiting the vulnerabilities to deliver a malware payload, it is unlikely that will remain the case for long.

The best defense against exploit kits is to ensure that software updates and patches are applied promptly, although that is not always possible for businesses and sometimes some devices are missed and remain vulnerable. An additional measure that can protect against exploit kits and other types of web-based malware distribution is a web filter.

Web filters are the Internet equivalent of spam filters. Just as a spam filter prevents the delivery of emails containing malware to inboxes, web filters prevent malware delivery via malicious websites and are a key component of anti-phishing defenses, preventing end-users from visiting websites hosting phishing kits.

TitanHQ has developed WebTitan to protect businesses from web-based threats and carefully control the content that can be accessed by office-based and remote workers. WebTitan is a DNS-based web filter that is quick and easy to implement, which has no impact on page load speeds. WebTitan is used by more than 12,000 businesses and managed service providers for content filtering, blocking malware delivery via the internet, and as an additional security measure to block phishing attacks.

If you want to improve protection against malware, malicious sites, phishing sites, C2 callbacks, ransomware, botnets, spyware, and viruses, give the TitanHQ team a call or put the solution to the test in your own environment by taking advantage of a 100% free 30-day trial of the full solution.