Characterising Payload Entropy in Packet Flows

Fuente: arXiv
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Auteurs principaux: Kenyon, Anthony, Deka, Lipika, Elizondo, David
Format: Preprint
Publié: 2024
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author Kenyon, Anthony
Deka, Lipika
Elizondo, David
author_facet Kenyon, Anthony
Deka, Lipika
Elizondo, David
contents Accurate and timely detection of cyber threats is critical to keeping our online economy and data safe. A key technique in early detection is the classification of unusual patterns of network behaviour, often hidden as low-frequency events within complex time-series packet flows. One of the ways in which such anomalies can be detected is to analyse the information entropy of the payload within individual packets, since changes in entropy can often indicate suspicious activity - such as whether session encryption has been compromised, or whether a plaintext channel has been co-opted as a covert channel. To decide whether activity is anomalous we need to compare real-time entropy values with baseline values, and while the analysis of entropy in packet data is not particularly new, to the best of our knowledge there are no published baselines for payload entropy across common network services. We offer two contributions: 1) We analyse several large packet datasets to establish baseline payload information entropy values for common network services, 2) We describe an efficient method for engineering entropy metrics when performing flow recovery from live or offline packet data, which can be expressed within feature subsets for subsequent analysis and machine learning applications.
format Preprint
id arxiv_https___arxiv_org_abs_2404_19121
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Characterising Payload Entropy in Packet Flows
Kenyon, Anthony
Deka, Lipika
Elizondo, David
Cryptography and Security
Accurate and timely detection of cyber threats is critical to keeping our online economy and data safe. A key technique in early detection is the classification of unusual patterns of network behaviour, often hidden as low-frequency events within complex time-series packet flows. One of the ways in which such anomalies can be detected is to analyse the information entropy of the payload within individual packets, since changes in entropy can often indicate suspicious activity - such as whether session encryption has been compromised, or whether a plaintext channel has been co-opted as a covert channel. To decide whether activity is anomalous we need to compare real-time entropy values with baseline values, and while the analysis of entropy in packet data is not particularly new, to the best of our knowledge there are no published baselines for payload entropy across common network services. We offer two contributions: 1) We analyse several large packet datasets to establish baseline payload information entropy values for common network services, 2) We describe an efficient method for engineering entropy metrics when performing flow recovery from live or offline packet data, which can be expressed within feature subsets for subsequent analysis and machine learning applications.
title Characterising Payload Entropy in Packet Flows
topic Cryptography and Security
url https://arxiv.org/abs/2404.19121