ZeroHour
Vendor

Advanced DNS Security

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Autoencoder Is All You Need: Profiling and Detecting Malicious DNS Traffic

Palo Alto Unit 42 details an autoencoder-based method that profiles DNS traffic to detect C2 and malicious domains, blocking ~374,000 malicious DNS requests daily.

Unit 42 built an RNN-based autoencoder that compresses DNS traffic time series into fixed-dimensional 'DNS profiles' for each domain and device. Downstream classification, clustering, and anomaly detection modules flag suspicious domains, capturing 170 emerging suspicious domains in May 2024. Signatures block roughly 374,000 malicious DNS requests daily and run in the Advanced DNS Security service, with detections shared to Advanced URL Filtering. Case studies link DNS traffic patterns to C2 beaconing, dynamic DNS abuse, and DNS tunneling for data exfiltration.

Palo Alto Unit 42 · Aug 17, 2026Research

Automatically Detecting DNS Hijacking in Passive DNS

Unit 42's machine learning pipeline detected 6,729 DNS hijacking events between March and September 2024, hitting political parties, ISPs, and universities.

Unit 42 processes roughly 167 million new DNS records daily and applies a machine learning model using 74 features over 169 TB of passive DNS and geolocation data to flag hijacked domains. From March to September 2024 the pipeline screened over 29 billion records and classified 6,729 as DNS hijacking, averaging 38 detections per day; a new model detects hijacks in customer traffic within about 10 minutes. Notable cases include a Hungarian political party's hijacked domain, defacement of a large utility company and ISP, and university and research center domains repurposed for illicit gambling. DNS hijacking typically relies on stolen registrar or DNS provider credentials or cache poisoning, enabling MitM attacks, phishing, drive-by downloads, and scams.

Palo Alto Unit 42 · Aug 17, 2026Research in the wild

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.

Palo Alto Unit 42 · Aug 17, 2026Research

The Smishing Deluge: China-Based Campaign Flooding Global Text Messages

Unit 42 attributes a global smishing campaign with 194,000+ phishing domains impersonating tolls, banks, and couriers to the Smishing Triad.

Palo Alto Unit 42 attributes ongoing smishing texts about toll violations and package misdelivery to the Smishing Triad, targeting U.S. residents since April 2024. Researchers identified 194,345 FQDNs across 136,933 root domains registered since January 2024, mostly via Hong Kong registrar Dominet (HK) Limited with Chinese nameservers and hosting concentrated on U.S. cloud services. The decentralized campaign impersonates banking, cryptocurrency, e-commerce, healthcare, law enforcement, and social media services, and its scale points to a large phishing-as-a-service operation. Phishing pages harvest national ID numbers such as Social Security numbers, home addresses, payment details, and login credentials.

Palo Alto Unit 42 · Aug 17, 2026Phishing & fraud in the wild1