Measuring Modern Phishing Tactics: A Quantitative Study of Body Obfuscation Prevalence, Co-occurrence, and Filter Impact

Fuente: arXiv
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Main Authors: Dalmiere, Antony, Zhou, Zheng, Auriol, Guillaume, Nicomette, Vincent, Marchand, Pascal
Format: Preprint
Published: 2025
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author Dalmiere, Antony
Zhou, Zheng
Auriol, Guillaume
Nicomette, Vincent
Marchand, Pascal
author_facet Dalmiere, Antony
Zhou, Zheng
Auriol, Guillaume
Nicomette, Vincent
Marchand, Pascal
contents Phishing attacks frequently use email body obfuscation to bypass detection filters, but quantitative insights into how techniques are combined and their impact on filter scores remain limited. This paper addresses this gap by empirically investigating the prevalence, co-occurrence patterns, and spam score associations of body obfuscation techniques. Analysing 386 verified phishing emails, we quantified ten techniques, identified significant pairwise co-occurrences revealing strategic layering like the presence of text in images with multipart abuse, and assessed associations with antispam scores using multilinear regression. Text in Image (47.0%), Base64 Encoding (31.2%), and Invalid HTML (28.8%) were highly prevalent. Regression (R${}^2$=0.486, p<0.001) linked Base64 Encoding and Text in Image with significant antispam evasion (p<0.05) in this configuration, suggesting potential bypass capabilities, while Invalid HTML correlated with higher scores. These findings establish a quantitative baseline for complex evasion strategies, underscoring the need for multi-modal defences against combined obfuscation tactics.
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id arxiv_https___arxiv_org_abs_2506_20228
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measuring Modern Phishing Tactics: A Quantitative Study of Body Obfuscation Prevalence, Co-occurrence, and Filter Impact
Dalmiere, Antony
Zhou, Zheng
Auriol, Guillaume
Nicomette, Vincent
Marchand, Pascal
Cryptography and Security
Phishing attacks frequently use email body obfuscation to bypass detection filters, but quantitative insights into how techniques are combined and their impact on filter scores remain limited. This paper addresses this gap by empirically investigating the prevalence, co-occurrence patterns, and spam score associations of body obfuscation techniques. Analysing 386 verified phishing emails, we quantified ten techniques, identified significant pairwise co-occurrences revealing strategic layering like the presence of text in images with multipart abuse, and assessed associations with antispam scores using multilinear regression. Text in Image (47.0%), Base64 Encoding (31.2%), and Invalid HTML (28.8%) were highly prevalent. Regression (R${}^2$=0.486, p<0.001) linked Base64 Encoding and Text in Image with significant antispam evasion (p<0.05) in this configuration, suggesting potential bypass capabilities, while Invalid HTML correlated with higher scores. These findings establish a quantitative baseline for complex evasion strategies, underscoring the need for multi-modal defences against combined obfuscation tactics.
title Measuring Modern Phishing Tactics: A Quantitative Study of Body Obfuscation Prevalence, Co-occurrence, and Filter Impact
topic Cryptography and Security
url https://arxiv.org/abs/2506.20228