Abstract-One of the key benefits of using intrusion-tolerant systems is the possibility of ensuring correct behavior in the presence of attacks and intrusions. These security gains are directly dependent on the components exhibiting failure diversity. To what extent failure diversity is observed in practical deployment depends on how diverse are the components that constitute the system. In this paper we present a study with operating systems (OS) vulnerability data from the NIST National Vulnerability Database. We have analyzed the vulnerabilities of 11 different OSes over a period of roughly 15 years, to check how many of these vulnerabilities occur in more than one OS. We found this number to be low for several combinations of OSes. Hence, our analysis provides a strong indication that building a system with diverse OSes may be a useful technique to improve its intrusion tolerance capabilities.

Abstract-Fault tolerance in the form of diverse redundancy is well known to improve the detection rates for both malicious and non-malicious failures. What is of interest to designers of security protection systems are the actual gains in detection rates that they may give. In this paper we provide exploratory analysis of the potential gains in detection capability from using diverse AntiVirus products for the detection of self-propagating malware. The analysis is based on 1599 malware samples collected by the operation of a distributed honeypot deployment over a period of 178 days. We sent these samples to the signature engines of 32 different AntiVirus products taking advantage of the VirusTotal service. The resulting dataset allowed us to perform analysis of the effects of diversity on the detection capability of these components as well as how their detection capability evolves in time.

Abstract

We have previously reported [1] the results of an exploratory analysis of the potential gains in detection capability from using diverse AntiVirus products. The analysis was based on 1599 malware samples collected from a distributed honeypot deployment over a period of 178 days. The malware samples were sent to the signature engines of 32 different AntiVirus products hosted by the VirusTotal service. The analysis suggested significant gains in detection capability from using more than one AntiVirus product in a one-out-oftwo intrusion-tolerant setup. In this paper we present new analysis of this dataset to explore the detection gains that can be achieved from using more diversity (i.e. more than two AntiVirus products), how diversity may help to reduce the "at risk time" of a system and a preliminary model-fitting using the hyper-exponential distribution.

If an off-the-shelf software product exhibits poor dependability due to design faults, then software fault tolerance is often the only way available to users and system integrators to alleviate the problem. Thanks to low acquisition costs, even using multiple versions of software in a parallel architecture, which is a scheme formerly reserved for few and highly critical applications, may become viable for many applications. We have studied the potential dependability gains from these solutions for off-the-shelf database servers. We based the study on the bug reports available for four off-the-shelf SQL servers plus later releases of two of them. We found that many of these faults cause systematic noncrash failures, which is a category ignored by most studies and standard implementations of fault tolerance for databases. Our observations suggest that diverse redundancy would be effective for tolerating design faults in this category of products. Only in very few cases would demands that triggered a bug in one server cause failures in another one, and there were no coincident failures in more than two of the servers. Use of different releases of the same product would also tolerate a significant fraction of the faults. We report our results and discuss their implications, the architectural options available for exploiting them, and the difficulties that they may present.

One of the key benefits of using intrusion-tolerant systems is the possibility of ensuring correct behavior in the presence of attacks and intrusions. These security gains are directly dependent on the components exhibiting failure diversity. To what extent failure diversity is observed in practical deployment depends on how diverse are the components that constitute the system. In this paper, we present a study with operating system's (OS's) vulnerability data from the NIST National Vulnerability Database (NVD). We have analyzed the vulnerabilities of 11 different OSs over a period of 18 years, to check how many of these vulnerabilities occur in more than one OS. We found this number to be low for several combinations of OSs. Hence, although there are a few caveats on the use of NVD data to support definitive conclusions, our analysis shows that by selecting appropriate OSs, one can preclude (or reduce substantially) common vulnerabilities from occurring in the replicas of the intrusion-tolerant system. ‡ A specific type of bug, regarding security, is usually called a vulnerability. Once a vulnerability is discovered, it can be maliciously exploited. If the exploited vulnerability leads to the software system deviating from its intended requirements or security policy, then the system is deemed to have failed. The system can fail on a single or combination of the following security properties: confidentiality, availability, and integrity. In the rest of this paper, we will use the terms fault and vulnerability interchangeably. 736 M. GARCIA ET AL.faulty. To satisfy this provision, system components need to exhibit failure diversity, that is, the probability that a majority of components fail at the same time should be negligible (or else the system as a whole will fail). This failure diversity assumption is easier to justify when one is concerned with accidental faults, such as power outages, disk crashes, or message corruption due to noise in communication lines. However, for design faults of any kind, including security vulnerabilities, the assumption is difficult to guarantee. If multiple components contain the same vulnerabilities, then a single attack can compromise all of them, therefore defeating the aim of intrusion tolerance system in providing improved security.To reduce the probability of vulnerabilities existing in more than one component, design diversity [3] can be employed: each component uses diverse software to perform the same functions, with the expectation that the differences will reduce the occurrence of common vulnerabilities, that is, vulnerabilities that exist in more than one system. Byzantine fault-tolerant replication often suggest the use of replica diversity (e.g., [4][5][6][7][8][9][10][11][12][13][14]), under the (sometimes implicit) assumption that they exhibit failure diversity. In this work, we want to empirically assess to what extent failure diversity is exhibited in a complex category of OTS software, namely operating systems (OSs).We focus our study on OS because they are a...

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Open Source Intelligence (OSINT) has taken the interest of cybersecurity practitioners due to its completeness and timeliness. In particular, Twitter has proven to be a discussion hub regarding the latest vulnerabilities and exploits. In this paper, we present a study comparing vulnerability databases between themselves and against Twitter. Although there is evidence of OSINT advantages, no methodological studies have addressed the quality and benefits of the sources available. We compare the publishing dates of more than nine-thousand vulnerabilities in the sources considered. We show that NVD is not the most timely or the most complete vulnerability database, that Twitter provides timely and impactful security alerts, that using diverse OSINT sources provides better completeness and timeliness of vulnerabilities, and provide insights on how to capture cybersecurity-relevant tweets.