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Automatic Derivation of Platform Noninterference Properties
KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS.ORCID iD: 0000-0003-3434-5640
KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS.ORCID iD: 0000-0001-5432-6442
2016 (English)In: Software Engineering and Formal Methods, Springer LNCS 9763 / [ed] Rocco De Nicola, Eva Kühn, 2016, 27-44 p.Conference paper (Refereed)
Abstract [en]

For the verification of system software, information flow properties of the instruction set architecture (ISA) are essential.They show how information propagates through the processor, including sometimes opaque control registers.Thus, they can be used to guarantee that user processes cannot infer the state of privileged system components, such as secure partitions.Formal ISA models - for example for the HOL4 theorem prover - have been available for a number of years. However, little work has been published on the formal analysis of these models.In this paper, we present a general framework for proving information flow properties of a number of ISAs automatically, for example for ARM.The analysis is represented in HOL4 using a direct semantical embedding of noninterference, and does not use an explicit type system, in order to (i) minimize the trusted computingbase, and to (ii) support a large degree of context-sensitivity, which is needed for the analysis.The framework determines automatically which system components are accessible at a given privilege level, guaranteeing both soundness and accuracy.

Place, publisher, year, edition, pages
2016. 27-44 p.
Series
, Lecture Notes in Computer Science, ISSN 0302-9743 ; 9763
Keyword [en]
Instruction set architectures, ARM, MIPS, noninterference, information flow, theorem proving, HOL4
National Category
Computer Science
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:kth:diva-192451DOI: 10.1007/978-3-319-41591-8_3ISBN: 978-3-319-41590-1ISBN: 978-3-319-41591-8OAI: oai:DiVA.org:kth-192451DiVA: diva2:968447
Conference
Software Engineering and Formal Methods (SEFM)
Projects
PROSPERHASPOCCERCES
Funder
VINNOVASwedish Foundation for Strategic Research Swedish Civil Contingencies Agency
Note

QC 20160916

Available from: 2016-09-12 Created: 2016-09-12 Last updated: 2016-09-16Bibliographically approved
In thesis
1. No Hypervisor Is an Island: System-wide Isolation Guarantees for Low Level Code
Open this publication in new window or tab >>No Hypervisor Is an Island: System-wide Isolation Guarantees for Low Level Code
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The times when malware was mostly written by curious teenagers are long gone. Nowadays, threats come from criminals, competitors, and government agencies. Some of them are very skilled and very targeted in their attacks. At the same time, our devices – for instance mobile phones and TVs – have become more complex, connected, and open for the execution of third-party software. Operating systems should separate untrusted software from confidential data and critical services. But their vulnerabilities often allow malware to break the separation and isolation they are designed to provide. To strengthen protection of select assets, security research has started to create complementary machinery such as security hypervisors and separation kernels, whose sole task is separation and isolation. The reduced size of these solutions allows for thorough inspection, both manual and automated. In some cases, formal methods are applied to create mathematical proofs on the security of these systems.

The actual isolation solutions themselves are carefully analyzed and included software is often even verified on binary level. The role of other software and hardware for the overall system security has received less attention so far. The subject of this thesis is to shed light on these aspects, mainly on (i) unprivileged third-party code and its ability to influence security, (ii) peripheral devices with direct access to memory, and (iii) boot code and how we can selectively enable and disable isolation services without compromising security.

The papers included in this thesis are both design and verification oriented, however, with an emphasis on the analysis of instruction set architectures. With the help of a theorem prover, we implemented various types of machinery for the automated information flow analysis of several processor architectures. The analysis is guaranteed to be both sound and accurate.

Abstract [sv]

Förr skrevs skadlig mjukvara mest av nyfikna tonåringar. Idag är våra datorer under ständig hot från statliga organisationer, kriminella grupper, och kanske till och med våra affärskonkurrenter. Vissa besitter stor kompetens och kan utföra fokuserade attacker. Samtidigt har tekniken runtomkring oss (såsom mobiltelefoner och tv-apparater) blivit mer komplex, uppkopplad och öppen för att exekvera mjukvara från tredje part.

Operativsystem borde egentligen isolera känslig data och kritiska tjänster från mjukvara som inte är trovärdig. Men deras sårbarheter gör det oftast möjligt för skadlig mjukvara att ta sig förbi operativsystemens säkerhetsmekanismer. Detta har lett till utveckling av kompletterande verktyg vars enda funktion är att förbättra isolering av utvalda känsliga resurser. Speciella virtualiseringsmjukvaror och separationskärnor är exempel på sådana verktyg. Eftersom sådana lösningar kan utvecklas med relativt liten källkod, är det möjligt att analysera dem noggrant, både manuellt och automatiskt. I några fall används formella metoder för att generera matematiska bevis på att systemet är säkert.

Själva isoleringsmjukvaran är oftast utförligt verifierad, ibland till och med på assemblernivå. Dock så har andra komponenters påverkan på systemets säkerhet hittills fått mindre uppmärksamhet, både när det gäller hårdvara och annan mjukvara. Den här avhandlingen försöker belysa dessa aspekter, huvudsakligen (i) oprivilegierad kod från tredje part och hur den kan påverka säkerheten, (ii) periferienheter med direkt tillgång till minnet och (iii) startkoden, samt hur man kan aktivera och deaktivera isolationstjänster på ett säkert sätt utan att starta om systemet.

Avhandlingen är baserad på sex tidigare publikationer som handlar om både design- och verifikationsaspekter, men mest om säkerhetsanalys av instruktionsuppsättningar. Baserat på en teorembevisare har vi utvecklat olika verktyg för den automatiska informationsflödesanalysen av processorer. Vi har använt dessa verktyg för att tydliggöra vilka register oprivilegierad mjukvara har tillgång till på ARM- och MIPS-maskiner. Denna analys är garanterad att vara både korrekt och precis. Så vitt vi vet är vi de första som har publicerat en lösning för automatisk analys och bevis av informationsflödesegenskaper i standardinstruktionsuppsättningar.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 180 p.
Series
TRITA-CSC-A, ISSN 1653-5723 ; 2016:22
Keyword
Platform Security, Hypervisor, Formal Verification, Theorem Proving, HOL4, DMA, Peripheral Devices, Instruction Set Architectures, ISA, Information Flow, Boot
National Category
Computer Science
Research subject
Computer Science
Identifiers
urn:nbn:se:kth:diva-192466 (URN)978-91-7729-104-6 (ISBN)
Public defence
2016-10-10, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Projects
PROSPERHASPOC
Funder
Swedish Foundation for Strategic Research VINNOVA
Note

QC 20160919

Available from: 2016-09-19 Created: 2016-09-12 Last updated: 2016-09-19Bibliographically approved

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