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DEEDS Meeting Oct., 26th 2006
Dependable, Embedded Systems and Software GroupDepartment of Computer ScienceDarmstadt University of Technology
Summary of my enquiries made so far…
Daniel Germanus <[email protected]>
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Intro
•Bachelor Thesis was on Threat Modeling
•Part of Microsofts Security Development Lifecycle
•Cons can be:
– Informal method
– Static approach
•Wanted:
– New, or improved attackability measures
– Based on exact models
– Dynamic system view
– (semi) automated
!
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How to achieve?
•Enquiries on Security, Metrics, Measures and related Technologies
•Looking for Metrics, Methods and Tools
• Metrics: Attack Surface, Risk measurement
• Methods: Attack Graphs
• Tools: OPUS
• In the future: model own metrics or methods
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Attack surface (CMU)
•Definition: Sum of accessible APIs and used resources
•Non-orthogonal, three dimensional mapping:
• Targets & Enablers (i.e. resources, processes and data)
• Channels & Protocols (2 types of channels: message passing and
shared memory, every channel associated with a protocol)
• Access rights: associated with all resources
•Developed state machine model for System, Threat and User behavior
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Attack surface (CMU)
•Calculating actual attackability …
–Relative, not absolute measure
–Different approaches possible:
• Use of domain specific attack classes (cf. Threat Modeling)
• Definition of own system/channel/data attack classes
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Attack surface (CMU)
•Example for some domain specific attack classes:
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Attack surface (CMU)
•Example for actual metric application
•Using
–two different versions of an IMAP server (IMAPD1 and IMAPD2)
–own system/channel/data attack classes
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IMAPD1 .. Attack surface value is triple <3.5 , 2 , 1.66>
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IMAPD2 .. Attack surface value is triple <5 , 2 , 1.33>
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Threat Index
•Metric with cost/benefit approach
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Threat Index Visualization
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Network Attack Graphs
•Per host basis algorithms
•Supports system analysts, automated graph generation
•Input parameters are:
–a set of host nodes, H
–a set of trust relationships, T
–a set of access edges, E
–a set of network exploits, X
–a set of vulnerabilities at each host, V
–a new attacker host, h
•At this stage, only known attacks are considered
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Network Attack Graphs
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Tools
•OPUS – Online Patches and Updates for Security
–Intention: minimize downtime
–Granularity: functions (with identical signature)
• No globals,
• no nonrecurring functions (like main),
• no functions which are currently on some stack frame
–Currently only supported for C programs
–Validated with several Bugtraq incident reports for buffer overflows,
double frees, etc.
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That‘s it
Thanks.
Please, visit the DEEDS Wiki on Security related content.
