Advertising is a key driver of revenue for many online platforms. However, it has also become a lucrative target for cybercriminals who exploit ad networks to distribute malicious software, a practice known as malvertising. The National Cyber Security Centre (NCSC) has been at the forefront of combating this growing threat, providing crucial guidance to help brands and advertising partners safeguard their campaigns and protect users.

What is Malvertising?

Malvertising refers to the use of online advertisements to spread malware. Unlike traditional phishing attacks, which typically rely on deceiving the user into clicking a malicious link, malvertising can compromise users simply by visiting a site where a malicious ad is displayed. This can lead to a range of cyber threats, including ransomware, data breaches, and financial theft.

The Scope of the Problem

The prevalence of malvertising is alarming. Cybercriminals leverage the vast reach of digital ads to target a large number of victims, often without their knowledge. According to NCSC, the complexity of the advertising ecosystem, which involves multiple intermediaries, exacerbates the issue. This makes identifying and blocking malicious ads challenging before they reach the end user.

Best Practices for Mitigating Malvertising

To combat malvertising, NCSC recommends adopting a defense-in-depth approach. Here are some best practices that organizations can implement:

• Partnering with well-established and trusted ad networks can reduce the risk of encountering malicious ads. Reputable networks have stringent security measures and vetting processes in place.
• Conducting regular security audits of ad campaigns can help identify and mitigate potential threats. This includes scanning for malicious code and ensuring that all ads comply with security standards.
• Ad verification tools can monitor and block malicious ads in real-time. These tools use machine learning algorithms to detect suspicious activity and prevent ads from being displayed to users.
• Educating users about the dangers of malvertising and encouraging them to report suspicious ads can help organizations identify and respond to threats more effectively.
• Ensuring that websites are secure and free from vulnerabilities can prevent cybercriminals from exploiting them to distribute malvertising. This includes regularly updating software and using robust security protocols.

Case Studies of Successful Mitigation

Several organizations have successfully implemented these best practices and seen significant reductions in malvertising incidents. For example, a major online retailer partnered with a top-tier ad network and implemented comprehensive ad verification tools. As a result, they were able to block over 90% of malicious ads before they reached their customers.