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Details of Grant 

EPSRC Reference: EP/K033344/1
Title: Mining the Network Behaviour of Bots
Principal Investigator: Cavallaro, Dr L
Other Investigators:
Vovk, Professor V Gammerman, Professor A Luo, Dr Z
Shanahan, Dr HP
Researcher Co-Investigators:
Project Partners:
Department: Information Security
Organisation: Royal Holloway, Univ of London
Scheme: Standard Research
Starts: 16 June 2013 Ends: 17 April 2017 Value (£): 680,623
EPSRC Research Topic Classifications:
Artificial Intelligence Networks & Distributed Systems
Statistics & Appl. Probability
EPSRC Industrial Sector Classifications:
Information Technologies
Related Grants:
Panel History:
Panel DatePanel NameOutcome
20 Feb 2013 EPSRC CEReS Feb 2013 Announced
Summary on Grant Application Form
The botnets phenomenon has quickly become a major security concern for all the

Internet users. In fact, not only has it rapidly gained popularity among the

mass media, but it has also received the attention of the research community

interested in understanding, analyzing, and detecting bot-infected machines.

Once infected with a bot, the victim host joins a botnet, a network of

compromised machines that are under the control of a malicious entity. Botnets

are the primary means for cyber-criminals to carry out criminal tasks,

such as sending spam mail, launching denial-of-service attacks, or stealing

personal data such as mail accounts or bank credentials.

Clustering and correlating network events represent the state-of-the-art when

it comes to detecting and understanding the botnets phenomenon from a network

perspective. While effective, such approaches rest on weak foundations being

vulnerable to easy-to-perform (time and network) obfuscation attacks.

The goal of this project is to build on the promising results of our previous

work to explore novel machine-learning techniques to make the state-of-the-art

more accurate and robust against evasions and advanced malware. Exploring the

possibilities of advanced malware (and thus bots) to enable the development of

novel mathematical techniques to address such threats is not a mere academic

exercise. On the contrary, it is of paramount importance to build robust and

hard-to-elude mitigation approaches; something we currently lack, as

acknowledged by the research community at large.

On the cyber security side, we will develop techniques to analyze the network

traffic generated by a bot sample. Our analysis will focus on inferring the

interesting part of a bot's network behaviour to automatically generate models

that faithfully describe it. Our analysis aims at being independent from the

underlying botnet infrastructure, payload-agnostic, and able to pinpoint

legitimate-resembling malicious activities. The network flows of a monitored

bot will be initially filtered to remove well-defined attack patterns. The

remaining flows will be clustered using a number of network features and

suitable similarity functions. Clusters whose size exceeds a given threshold

will then be analyzed for periodicity: bots tend to engage in similar network

activities that have interflow intervals that either are sampled independently

from a potentially unknown probability distribution, or belong to a small

number of well-defined clusters. Once clusters exhibiting interesting

periodicity patterns are identified, they can be used, along with their network

features, for detecting (or understanding the behaviour of) bots in a mixed

population containing both compromised and clean hosts.

On the machine learning side, we propose to explore the use of conformal

prediction developed by our team to make such cluster-based analysis more

accurate and robust against arbitrary obfuscation-based evasion attacks. A

powerful clustering method is based on nonparametric probability density

estimation. A recent work proposes a computationally efficient method of

nonparametric density estimation based on conformal prediction and inherits its

properties of validity. We plan to explore the use of this method for the

purpose of robust clustering. A theoretical challenge is to spell out and study

the properties of robustness for this clustering method that are inherited from

the validity of the study mentioned above. In addition, the property of

validity of conformal predictors is usually established under the randomness

assumption; we will explore how this assumption can be relaxed. In addition,

the property of validity can be used to control the number of "alarms"

(predicting that a host is compromised) raised by a bot detection algorithm.

This is valuable in situations where alarms have to be investigated by human

experts but the available manpower is limited.
Key Findings
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Potential use in non-academic contexts
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