DeepSec 2022 Talk: Fighting Fire with Fire – Detecting DNS-Tunneling with DNS – Artsiom Holub
DNS tunneling used as a covert-channel method to bypass security policies has ballooned in the landscape of Ransomware attacks in recent years. This can be attributed to CobaltStrike post exploitation tools becoming modus operandi of cybercrime syndicates operating with ransomware. Most of the detections rely on packet inspection, which suffers from scalability performance when an extensive set of sockets should be monitored in real time. Aggregation-based monitoring avoids packet inspection, but has two drawbacks: silent intruders (generating small statistical variations of legitimate traffic) and quick statistical fingerprints generation (to obtain a detection tool really applicable in the field). Our approach uses statistical analysis coupled with behavioral characteristics applied directly in the DNS resolver. This presentation will cover examples of the malicious tools used by threat actors and detections designed to protect from such tools.