Peek Inside the Closed World: Evaluating Autoencoder-Based Detection of DDoS to Cloud. Guo, H., Fan, X., Cao, A., Outhred, G., & Heidemann, J. Technical Report arXiv:1912.05590v2 [cs.NI], arXiv, December, 2019.
Peek Inside the Closed World: Evaluating Autoencoder-Based Detection of DDoS to Cloud [link]Paper  abstract   bibtex   
Machine-learning-based anomaly detection (ML-based AD) has been successful at detecting DDoS events in the lab. However published evaluations of ML-based AD have only had limited data and have not provided insight into why it works. To address limited evaluation against real-world data, we apply autoencoder, an existing ML-AD model, to 57 DDoS attack events captured at 5 cloud IPs from a major cloud provider. To improve our understanding for why ML-based AD works or not works, we interpret this data with feature attribution and counterfactual explanation. We show that our version of autoencoders work well overall: our models capture nearly all malicious flows to 2 of the 4 cloud IPs under attacks (at least 99.99%) but generate a few false negatives (5% and 9%) for the remaining 2 IPs. We show that our models maintain near-zero false positives on benign flows to all 5 IPs. Our interpretation of results shows that our models identify almost all malicious flows with non-whitelisted (non-WL) destination ports (99.92%) by learning the full list of benign destination ports from training data (the normality). Interpretation shows that although our models learn incomplete normality for protocols and source ports, they still identify most malicious flows with non-WL protocols and blacklisted (BL) source ports (100.0% and 97.5%) but risk false positives. Interpretation also shows that our models only detect a few malicious flows with BL packet sizes (8.5%) by incorrectly inferring these BL sizes as normal based on incomplete normality learned. We find our models still detect a quarter of flows (24.7%) with abnormal payload contents even when they do not see payload by combining anomalies from multiple flow features. Lastly, we summarize the implications of what we learn on applying autoencoder-based AD in production.problme?Machine-learning-based anomaly detection (ML-based AD) has been successful at detecting DDoS events in the lab. However published evaluations of ML-based AD have only had limited data and have not provided insight into why it works. To address limited evaluation against real-world data, we apply autoencoder, an existing ML-AD model, to 57 DDoS attack events captured at 5 cloud IPs from a major cloud provider. To improve our understanding for why ML-based AD works or not works, we interpret this data with feature attribution and counterfactual explanation. We show that our version of autoencoders work well overall: our models capture nearly all malicious flows to 2 of the 4 cloud IPs under attacks (at least 99.99%) but generate a few false negatives (5% and 9%) for the remaining 2 IPs. We show that our models maintain near-zero false positives on benign flows to all 5 IPs. Our interpretation of results shows that our models identify almost all malicious flows with non-whitelisted (non-WL) destination ports (99.92%) by learning the full list of benign destination ports from training data (the normality). Interpretation shows that although our models learn incomplete normality for protocols and source ports, they still identify most malicious flows with non-WL protocols and blacklisted (BL) source ports (100.0% and 97.5%) but risk false positives. Interpretation also shows that our models only detect a few malicious flows with BL packet sizes (8.5%) by incorrectly inferring these BL sizes as normal based on incomplete normality learned. We find our models still detect a quarter of flows (24.7%) with abnormal payload contents even when they do not see payload by combining anomalies from multiple flow features. Lastly, we summarize the implications of what we learn on applying autoencoder-based AD in production.
@TechReport{Guo19a,
        author =        "Hang Guo and Xun Fan and Anh Cao and Geoff
                  Outhred and John Heidemann",
        title =         "Peek Inside the Closed World: Evaluating Autoencoder-Based Detection of {DDoS} to Cloud",
	institution = 	"arXiv",
        year =          2019,
	sortdate = 		"2019-12-16", 
	project = "ant, lacanic",
	jsubject = "topology_modeling",
        number =     "arXiv:1912.05590v2 [cs.NI]",
        month =      dec,
	jlocation = 	"johnh: pafile",
	keywords = 	"ddos, cloud, machine learning, autoencoder",
	url =		"https://ant.isi.edu/%7ejohnh/PAPERS/Guo19a.html",
	otherurl =		"https://ant.isi.edu/%7ehangguo/papers/Guo19a.pdf",
	pdfurl =	"https://ant.isi.edu/%7ejohnh/PAPERS/Guo19a.pdf",
	blogurl = "https://ant.isi.edu/blog/?p=1401",
        abstract = "Machine-learning-based anomaly detection (ML-based AD) has been
successful at detecting DDoS events in the lab. However published
evaluations of ML-based AD have only had limited data and have not
provided insight into why it works. To address limited evaluation
against real-world data, we apply autoencoder, an existing ML-AD
model, to 57 DDoS attack events captured at 5 cloud IPs from a major
cloud provider. To improve our understanding for why ML-based AD works
or not works, we interpret this data with feature attribution and
counterfactual explanation. We show that our version of autoencoders
work well overall: our models capture nearly all malicious flows to 2
of the 4 cloud IPs under attacks (at least 99.99\%) but generate a few
false negatives (5\% and 9\%) for the remaining 2 IPs. We show that our
models maintain near-zero false positives on benign flows to all 5
IPs. Our interpretation of results shows that our models identify
almost all malicious flows with non-whitelisted (non-WL) destination
ports (99.92\%) by learning the full list of benign destination ports
from training data (the normality). Interpretation shows that although
our models learn incomplete normality for protocols and source ports,
they still identify most malicious flows with non-WL protocols and
blacklisted (BL) source ports (100.0\% and 97.5\%) but risk false
positives. Interpretation also shows that our models only detect a few
malicious flows with BL packet sizes (8.5\%) by incorrectly inferring
these BL sizes as normal based on incomplete normality learned. We
find our models still detect a quarter of flows (24.7\%) with abnormal
payload contents even when they do not see payload by combining
anomalies from multiple flow features. Lastly, we summarize the
implications of what we learn on applying autoencoder-based AD in
production.problme?Machine-learning-based anomaly detection (ML-based
AD) has been successful at detecting DDoS events in the lab. However
published evaluations of ML-based AD have only had limited data and
have not provided insight into why it works. To address limited
evaluation against real-world data, we apply autoencoder, an existing
ML-AD model, to 57 DDoS attack events captured at 5 cloud IPs from a
major cloud provider. To improve our understanding for why ML-based AD
works or not works, we interpret this data with feature attribution
and counterfactual explanation. We show that our version of
autoencoders work well overall: our models capture nearly all
malicious flows to 2 of the 4 cloud IPs under attacks (at least
99.99\%) but generate a few false negatives (5\% and 9\%) for the
remaining 2 IPs. We show that our models maintain near-zero false
positives on benign flows to all 5 IPs. Our interpretation of results
shows that our models identify almost all malicious flows with
non-whitelisted (non-WL) destination ports (99.92\%) by learning the
full list of benign destination ports from training data (the
normality). Interpretation shows that although our models learn
incomplete normality for protocols and source ports, they still
identify most malicious flows with non-WL protocols and blacklisted
(BL) source ports (100.0\% and 97.5\%) but risk false
positives. Interpretation also shows that our models only detect a few
malicious flows with BL packet sizes (8.5\%) by incorrectly inferring
these BL sizes as normal based on incomplete normality learned. We
find our models still detect a quarter of flows (24.7\%) with abnormal
payload contents even when they do not see payload by combining
anomalies from multiple flow features. Lastly, we summarize the
implications of what we learn on applying autoencoder-based AD in
production.",
}

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