The Year in Web Threats: Web Skimmers Take Advantage of Cloud Hosting and More
Unit 42 analyzed 2.24 million web threat incidents, finding web skimmers increasingly hosted on cloud infrastructure to steal payment card data.
Palo Alto Unit 42 analyzed 2,241,354 web threat incidents and 831,550 unique URLs detected via Advanced URL Filtering between October 2020 and September 2021. Threat activity peaked from October 2020 to January 2021, coinciding with the holiday shopping season, with most malicious domains geolocated to the United States, Russia, and Germany. Web skimmers ranked third among the top five threat classes and showed the most code diversity, making detection harder. Researchers observed more web skimmer families being hosted on cloud platforms to steal payment data and PII.
Trends in Web Threats: Attackers Were More Active During Holiday Season
Unit 42 tracked 533,000 malicious landing URL incidents from October-December 2021, showing web threats peaked during the holiday shopping season.
Unit 42 detected 533,452 malicious landing URL incidents (120,753 unique) and 2,906,875 malicious host URL incidents (165,255 unique) from October through December 2021. Threat activity peaked in November, likely tied to Black Friday in the United States, United Kingdom, and Germany. Most malicious domains appeared to originate in the United States, followed by Russia and Germany. Personal sites, blogs, business sites, and shopping sites were the most common apparently benign entry points for attacks.
Trends in Web Threats: Old Web Skimmer Still Active Today
Unit 42 detected 577,000 landing URL incidents in Q1 2022, with an old web skimmer family still actively stealing payment card data.
Palo Alto Unit 42 detected 577,275 landing URL incidents (116,643 unique) and 2,043,862 malicious host URL incidents (180,370 unique) between January and March 2022. Web threat volumes declined after the November 2021 holiday peak, but an old web skimmer family remained active. Business and economy sites overtook personal sites as the most common apparently benign entry points. Most malicious domains geolocated to the United States, Germany, and Russia, though proxy servers and VPNs obscure true locations.
Beneath the Surface: Detecting and Blocking Hidden Malicious Traffic Distribution Systems
Unit 42 built an ML-based detector for malicious traffic distribution systems, finding malicious TDS chains average longer redirections and more URLs than legitimate ones.
Traffic distribution systems redirect victims through chains of intermediate domains to hide final destinations, serving phishing, malvertising, and online gambling operations. Unit 42's topological analysis of redirection graphs found malicious TDS traffic uses longer chains (about 25% exceed four hops vs 10% benign), more URLs (median 126 vs 80), and fewer isolated subgraphs with higher connectivity. These features power an ML detector integrated into Advanced DNS Security and Advanced URL Filtering to identify and block malicious TDS infrastructure in customer traffic.