Study Identifies Risks Associated with 3rd and 4th Party Scripts on Websites

A recent study by Source Defense examined the risks associated with the use of third- and fourth-party code on websites and found that all modern, dynamic websites included code that could be targeted by hackers to gain access to sensitive data.

SOurce Defense explained that websites typically have their own third-party supply chains, with those third parties providing a range of services and functions related to site performance, tracking and analytics, and improving conversion rates to generate more sales.

The inclusion of third- and fourth-party code on websites also introduces security and compliance risks. On the compliance side, tracking code has the potential to violate data privacy laws such as the EU’s General Data Protection Regulation (GDPR) and from a security perspective, the code included on websites may have vulnerabilities that can be exploited by threat actors to gain access to sensitive data, including protected health information.

To explore the risks associated with third- and fourth-party code, Source Defense scanned the top 4,300 websites based on traffic and analyzed their results to identify the scale of the digital supply chain, how many partners are involved on a typical website, whether the inclusion of code by those partners leaves websites exposed to cyberattacks, whether sensitive data is being exposed, and the types of attacks that could be conducted on websites that take advantage of the digital supply chain.

The findings of the analysis are detailed in the report, Third-Party Digital Supply Chain Risk: Exposing the Shadow Code on Your Web Properties. Source Defense explained that there would be little point in a threat actor compromising a script on a static webpage; however, if scripts were included on webpages that collect sensitive data, threat actors could add malicious code to steal sensitive data. The researchers found that, on average, there were 12 third-party and 3 fourth-party scripts per website on web pages that collected data, such as login pages, account registration pages, and payment collection pages.

They identified six features on websites that could be exploited by threat actors that were commonly found on websites: Code to retrieve form input (49%), button click listeners (49%), link click listeners (43%), code to modify forms (23%), form submit listeners (22%), and input change listeners (14%). Every modern, dynamic website assessed for the study was found to contain one or more of those features.

An analysis was conducted of between 40 and 50 websites in industries where there is a higher-than-average risk. The researchers found that higher-risk industries such as healthcare had more than the average number of scripts. Healthcare websites had an average of 13 third-party and 5 fourth-party scripts on sensitive pages.

There may be a legitimate reason for including these scripts on the pages but adding that code introduces risk. “For example, a script might allow form fields to be changed or added on the fly to provide website users with a more personalized experience,” explained Source Defense in the report. “However, a threat actor could exploit this capability to add additional fields asking for credentials and personal information, which would then be sent to attacker’s website.”

“This data makes it clear that managing risk inherent in third- and fourth-party scripts is both a very necessary and a very challenging task,” explained the researchers, who recommend assessing websites for third party code, educating management about the risks, implementing a website client-side security solution, categorizing and consolidating scripts, and finding ways to recuse exposure and compliance risks.

Author: Steve Alder has many years of experience as a journalist, and comes from a background in market research. He is a specialist on legal and regulatory affairs, and has several years of experience writing about HIPAA. Steve holds a B.Sc. from the University of Liverpool.

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