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eScholarship
Open Access Publications from the University of California

Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Santa Barbara Electronic Theses and Dissertations (2018)

Mobile systems, such as smartphones and tablets, are now the most common way users handle digital

information and interact with online services.

The interaction with these devices encompasses different actors, trusting each other in different ways. Users interact with apps, trusting them to access valuable and privacy-sensitive information.

At the same time, apps usually communicate with remote backends and mediate user authentication to online services. Finally, all these interactions are mediated, on one side, by the user interface and, on the other, by the operating system.

In this thesis, I will present my studies on how all these different actors trust each other and how this trust can be unfortunately violated by attackers.

This is possible due to limitations on how the operating system, apps, and the user interface are currently designed and implemented.

To assist my work, I developed automatic analysis tools to perform large-scale analyses of Android apps.

In this thesis, I will describe both the tools I have developed and my findings.

Specifically, I will first describe my work on how, in an Android system, it is possible to lure users to interact with malicious apps which ``look like'' legitimate ones. This completely violates the trust relationship, mediated by the user interface, between users and apps.

As a countermeasure, I implemented modifications of the Android user interface and evaluated their effectiveness with a user study.

Then, I will explain how many apps unsafely authenticate their users to remote backends, due to misplaced trust in the operating system.

In particular, I identified different apps that only rely on values provided by the operating system to perform authentication. For this reason, an attacker can trivially spoof these values, and logins in behalf of a legitimate user.

Finally, I will show how many apps misuse hardware-backed authentication devices, such as trusted execution environments and fingerprint readers, making them vulnerable to a variety of authentication bypass attacks

    Cover page: Identifying and Mitigating Trust Violations in the Mobile Ecosystem
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2006)
    Aedes (Stegonryia) aegypti is an important dengue vector in tropical and subtropical zones throughout the world. A transcriptome of Ae. aegypti vitellogenic fat bodies is described here. The fat body is a dynamic tissue that participates in multiple biochemical functions of intermediate metabolism. A total Of 589 randomly selected eDNAs were assembled into 262 clusters based on their primary sequence similarities. The putative translated proteins were classified into categories based on their function in accordance with significant similarity using the BlastX at NCBI FFP site and Pfam (Bateman et al. 2000) and SMART (Schultz et al. 2000) databases. The characterization of transcripts expressed in the fat body of Ae. aegypti at 24 hours post blood meal provides a basic tool for understanding the processes occurring in this organ and could identify putative new genes whose promoters can be used to specifically express transgenes in the fat bodies of Ae.-aegypti.
      Cover page: A transcriptome analysis of the Aedes aegypti vitellogenic fat body
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2021)
      Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types.
        Cover page: SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues
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