Period 1

D1.1 “Security requirements for connected medium security-critical applications“ [September 2017]
This deliverable reports the general methodology developed in T1.1., in which general guidelines for requirement analyses will be reviewed and particularized with respect to the project scope.

D1.3 “Modelling framework Description“ [June 2018]
This document describes the model-based language resulting from T1.2.

D2.1. “Basic analyzers intermediate release“[June 2018]
Initial version of front-ends and specification libraries, improved analyzers and prototypes of new analyzers.

D3.1 „Methodological report for modular reasoning for system validation and verification“ [June 2018]
This report will contain the methodology about modular reasoning for system validation and verification (task 3.1).

D4.1 “Metrics for VESSEDIA tools in quality assurance“ [June 2018]
In this deliverable, the definition of metrics defined in Task 4.1. are stated and described.

D4.2 “VESSEDIA approach for security evaluation“ [June 2018]
D4.2 includes the analysis on using VESSEDIA results in security evaluation methodologies (Task 4.2).

Period 2

D1.5 “Analyses choice methodology report” [December 2018]
This report presents the findings of T1.4 “Flexible selection of static analyses” regarding a cost-efficient trade-off between basic and sophisticated analyses.

D1.6 Economic Rationale and metrics report [March 2019]
Economic rationale and metrics report of the effectiveness and efficiency of the use of VESSEDIA outcomes This deliverable consists of an academic publication on the topic of the economic rationale (effectiveness and efficiency) on the incentives for the advanced use of VESSEDIA outcomes based on use cases.

D1.7 “Vulnerability discovery methodology” [December 2018]
This report presents ways to detect the most common vulnerabilities using Frama-C.

D3.3 “Guidelines for combination of static and dynamic analyses” [December 2018]
This report is the output of task 3.2 and will contain guidelines for combination of static and dynamic analyses.

D3.2 Preliminary version of the platforms [August 2018]
This deliverable will contain the first prototypes of an environment of technologies to enable modular system verifications and of the “verification as a service” (tasks 3.1 and 3.3)

The VESSEDIA project uses Zenodo as its open research data repository, in order to grant Open Access to scientific publications. Check out our Zenodo community VESSEDIA!


Transferring obligations through synchronizations
Hamin Jafar; Jacobs Bart, ECOOP 2019, July 2019, London, United Kingdom
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Abstract: One common approach for verifying safety properties of multithreaded programs is assigning appropriate permissions, such as ownership of a heap location, and obligations, such as an obligation to send a message on a channel, to each thread and making sure that each thread only performs the actions for which it has permissions and it also fulfills all of its obligations before it terminates. Although permissions can be transferred through synchronizations from a sender thread, where for example a message is sent or a condition variable is notified, to a receiver thread, where that message or that notification is received, in existing approaches obligations can only be transferred when a thread is forked. In this paper we introduce two mechanisms, one for channels and the other for condition variables, that allow obligations, along with permissions, to be transferred from the sender to the receiver, while ensuring that there is no state where the transferred obligations are lost, i.e. where they are discharged from the sender thread but not loaded onto the receiver thread yet. We show how these mechanisms can be used to modularly verify deadlock-freedom of a number of interesting programs, such as some variations of client-server programs, fair readers-writers locks, and dining philosophers, which cannot be modularly verified without such transfer. We also encoded the proposed separation logic-based proof rules in the VeriFast program verifier and succeeded in verifying the mentioned programs.

Logic against Ghosts: Comparison of Two Proof Approaches for a List Module
Blanchard, Allan; Kosmatov, Nikolai; Loulergue, Frédéric, "The 34th ACM/SIGAPP Symposium On Applied Computing", Apr 2019, Limassol, Cyprus.
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Abstract: Modern verification projects continue to offer new challenges for formal verification. One of them is the linked list module of Contiki, a popular open-source operating system for the Internet of Things. It has a rich API and uses a particular list representation that make it different from the classical linked list implementations. Being widely used in the OS, the list module is critical for reliability and security. A recent work verified the list module using ghost arrays. This article reports on a new verification effort for this module. Realized in the Frama-C/Wp tool, the new approach relies on logic lists. A logic list provides a convenient high-level view of the linked list. The specifications of all functions are now proved faster and almost all automatically, only a small number of auxiliary lemmas and a couple of assertions being proved interactively in Coq. The proposed specifications are validated by proving a few client functions manipulating lists. During the verification, a more efficient implementation for one function was found and verified. We compare the new approach with the previous effort based on ghost arrays, and discuss the benefits and drawbacks of both techniques.


Synthesizing Invariants by Solving Solvable Loops
Steven de Oliveira, Saddek Bensalem, Virgile Prevosto
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Abstract: Formal program verification faces two problems. The first problem is related to the necessity of having automated solvers that are powerful enough to decide whether a formula holds for a set of proof obligations as large as possible, whereas the second manifests in the need of finding sufficiently strong invariants to obtain correct proof obligations. This paper focuses on the second problem and describes a new method for the automatic generation of loop invariants that handles polynomial and non deterministic assignments. This technique is based on the eigenvector generation for a given linear transformation and on the polynomial optimization problem, which we implemented on top of the open-source tool Pilat.

Ghosts for Lists: A Critical Module of Contiki Verified in Frama-C
Allan Blanchard, Nikolai Kosmatov, Frédéric Loulergue
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Abstract: Internet of Things (IoT) applications are becoming increasingly critical and require rigorous formal verification. In this paper we target Contiki, a widely used open-source OS for IoT, and present a verification case study of one of its most critical modules: that of linked lists. Its API and list representation differ from the classical linked list implementations, and are particularly challenging for deductive verification. The proposed verification technique relies on a parallel view of a list through a companion ghost array. This approach makes it possible to perform most proofs automatically using the Frama-C/WP tool, only a small number of auxiliary lemmas being proved interactively in the Coq proof assistant. We present an elegant segment-based reasoning over the companion array developed for the proof. Finally, we validate the proposed specification by proving a few functions manipulating lists.

Ghosts for Lists: from Axiomatic to Executable Specications
Frederic Loulergue, Allan Blanchard, and Nikolai Kosmatov
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Abstract: Internet of Things (IoT) applications are becoming increasingly critical and require formal verification. Our recent work presented formal verification of the linked list module of Contiki, an OS for IoT. It relies on a parallel view of a linked list via a companion ghost array and uses an inductive predicate to link both views. In this work, a few interactively proved lemmas allow for the automatic verification of the list functions specifications, expressed in the acsl specification language and proved with the Frama-C/Wp tool. In a broader verification context, especially as long as the whole system is not yet formally verified, it would be very useful to use runtime verification , in particular, to test client modules that use the list module. It is not possible with the current specifications, which include an inductive predicate and axiomatically defined functions. In this early-idea paper we show how to define a provably equivalent non-inductive predicate and a provably equivalent non-axiomatic function that belong to the executable subset e-acsl of acsl and can be transformed into executable C code. Finally, we propose an extension of Frama-C to handle both axiomatic specifications for deductive verification and executable specifications for runtime verification.

MMFilter: A CHR-Based Solver for Generation of Executions under Weak Memory Models
Allan Blanchard, Nikolai Kosmatov, Frédéric Loulergue
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Abstract: With the wide expansion of multiprocessor architectures, the analysis and reasoning for programs under weak memory models has become an important concern. This work presents MMFilter, an original constraint solver for generating program behaviors respecting a particular memory model. It is implemented in Prolog using CHR (Constraint Handling Rules). The CHR formalism provides a convenient generic solution for specifying memory models. It benefits from the existing optimized implementations of CHR and can be easily extended to new models. We present MMFilter design, illustrate the encoding of memory model constraints in CHR and discuss the benefits and limitations of the proposed technique.

Towards Formal Verification of Contiki: Analysis of the AES–CCM* Modules with Frama-C
A. Peyrard, N. Kosmatov, S. Duquennoy, S. Raza, "RED-IOT 2018 - Workshop on Recent advances in secure management of data and resources in the IoT", February 2018
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Abstract: The number of Internet of Things (IoT) applications is rapidly increasing and allows embedded devices today to be massively connected to the Internet. This raises software security questions. This paper demonstrates the usage of formal verification to increase the security of Contiki, a popular open-source operating system for the IoT. We present a case study on deductive verification of encryption-decryption modules of Contiki (namely, AES–CCM*) using Frama-C, a software analysis platform for C code.


Static Analysis and Runtime-Assertion Checking: Contribution to Security Counter-Measures
D. Pariente, J. Signoles, "SSTIC - Symposium sur la sécurité des technologies de l'information et des communications", June 2017
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Abstract: This paper presents a methodology which combines static analysis and runtime assertion checking in order to automatically generate counter-measures, and execute them whenever a flaw in the code which may compromise the security of an application is detected during execution. Static analysis pinpoints alarms that must be converted into runtime checks. Therefore the verifier is able to only monitor the security critical points of the application. This method allows to strengthen a security-critical source code in a cost-effective manner. We implemented it in the Frama-C framework and experimented it on a real use case based on Apache web server. The paper ends with preliminary considerations on potential perspectives for security evaluation and certification.

"ACSL By Example - Towards a Verified C Standard Library"
J. Burghardt, R. Clausecker, J. Gerlach, H. Pohl, for Frama-C Silicon, April 2017
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Abstract: This report provides various examples for the formal specification, implementation, and deductive verification of C programs using the ANSI/ISO-C Specification Language and the Frama-C/WP plug-in of Frama-C (Framework for Modular Analysis of C programs). We have chosen our examples from the C++ standard library whose initial version is still known as the Standard Template Library (STL). The STL contains a broad collection of generic algorithms that work not only on C arrays but also on more elaborate container data structures. For the purposes of this document we have selected representative algorithms, and converted their implementation from C++ function templates to C functions that work on arrays of type int. We will continue to extend and refine this report by describing additional STL algorithms and data structures. Thus, step by step, this document will evolve from an ACSL tutorial to a report on a formally specified and deductively verified standard library for ANSI/ISO-C. Moreover, as ACSL is extended to a C++ specification language, our work may be extended to a deductively verified C++ Standard Library.


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