Detection of Application Layer Protocol

ID: DET0685
Domains: Mobile
Analytics: AN1793, AN1794
Version: 1.0
Created: 21 October 2025
Last Modified: 21 October 2025

Analytics

AN1793

A defender observes an application establishing application-layer network sessions (e.g., HTTP(S), WebSocket, DNS, SMTP/IMAP) with destinations and request patterns that deviate from the enterprise baseline for that app category, especially when sessions occur during background execution or while the device is locked and exhibit beacon-like periodicity, anomalous SNI/Host patterns, or suspicious request/response size symmetry consistent with command polling and tasking over legitimate-looking protocols.

Log Sources
Data Component Name Channel
Network Traffic Flow (DC0078) NSM:Flow Application-layer protocol traffic exhibiting beacon-like periodicity, anomalous session structure, or protocol misuse patterns
Network Traffic Content (DC0085) NSM:Flow Application-layer indicators observable via enterprise network controls (HTTP method, URI path pattern class, TLS SNI, JA3/ALPN when available, DNS qname/type) showing anomalous or low-and-slow command polling behavior
OS API Execution (DC0021) MobileEDR:telemetry Framework-based networking usage spikes or uncommon networking stacks observed by agent telemetry (e.g., repeated URLSession/OkHttp-like patterns) without corresponding foreground/user interaction
Mutable Elements
Field Description
BeaconIntervalVarianceThreshold Defines acceptable periodicity variance for network communications
ConnectionFrequencyThreshold Baseline-dependent threshold for anomalous connection rates
PayloadEntropyThreshold Defines anomaly conditions for encoded or structured payload content

AN1794

A defender observes an application generating application-layer communications that blend with normal traffic (HTTP(S), WebSocket, DNS, mail protocols) but show deviations from enterprise baselines for that bundle ID—such as persistent background network sessions, regular low-volume polling intervals, anomalous SNI/Host destinations, uncommon DNS patterns, or uniform request/response sizing—suggesting command and control over legitimate-looking protocols without relying on tool signatures.

Log Sources
Data Component Name Channel
Network Traffic Flow (DC0078) NSM:Flow Application-layer protocol traffic exhibiting beacon-like periodicity, anomalous session structure, or protocol misuse patterns
Network Traffic Content (DC0085) NSM:Flow Application-layer indicators observable via enterprise network controls (HTTP method, URI path pattern class, TLS SNI, JA3/ALPN when available, DNS qname/type) showing anomalous or low-and-slow command polling behavior
OS API Execution (DC0021) MobileEDR:telemetry Framework-based networking usage spikes or uncommon networking stacks observed by agent telemetry (e.g., repeated URLSession/OkHttp-like patterns) without corresponding foreground/user interaction
Mutable Elements
Field Description
CadenceAnomalyThreshold Defines acceptable deviation in protocol communication timing
SessionPersistenceThreshold Baseline deviation tolerance for long-lived sessions
AppNetworkBehaviorBaseline Expected mapping of application functionality to protocol usage