Search for: All records

Chlamydiae represent a diverse group of obligate intracellular bacteria with elusive hosts in environmental settings. This study used one of the largest collections of wild amoebae (Dictyostelium discoideum and D. giganteum, 106 clones) collected over the past two decades to screen for novel environmental chlamydiae. We found that novel environmental chlamydiae are prevalent in two wild Dictyostelium species and assembled 42 novel chlamydiae metagenome-assembled genomes (MAGs). The MAGs represent three chlamydiae species previously only reported using 16S sequencing. Their genomes are divergent enough from other species to warrant placing them in two new genera (tentatively called Ca. Dictychlamydia sp. LF1, Ca. Dictychlamydia sp. LF2, and Ca. Feichlamydia sp. LF3). In addition, these chlamydiae species show strong host specificity with two Dictyostelium amoeba hosts, except one amoeba sample. Ca. Dictychlamydia sp. LF1 and Ca. Feichlamydia sp. LF3 was exclusively observed in D. discoideum, while Ca. Dictychlamydia sp. LF2 was found only in D. giganteum. Phylogenetic and comparative genomic analyses suggest that all three chlamydiae are close to arthropod-associated chlamydiae and likely have some intermediate characteristics between previously reported amoeba-associated and vertebrate-associated chlamydiae. This study significantly broadens our understanding of the chlamydial host range and underscores the role of amoebae as vital hosts for environmental chlamydiae. 

The massive trend toward embedded systems introduces new security threats to prevent. Malicious firmware makes it easier to launch cyberattacks against embedded systems. Systems infected with malicious firmware maintain the appearance of normal firmware operations but execute undesirable activities, which is usually a security risk. Traditionally, cybercriminals use malicious firmware to develop possible back-doors for future attacks. Due to the restricted resources of embedded systems, it is difficult to thwart these attacks using the majority of contemporary standard security protocols. In addition, monitoring the firmware operations using existing side channels from outside the processing unit, such as electromagnetic radiation, necessitates a complicated hardware configuration and in-depth technical understanding. In this paper, we propose a physical side channel that is formed by detecting the overall impedance changes induced by the firmware actions of a central processing unit. To demonstrate how this side channel can be exploited for detecting firmware activities, we experimentally validate it using impedance measurements to distinguish between distinct firmware operations with an accuracy of greater than 90%. These findings are the product of classifiers that are trained via machine learning. The implementation of our proposed methodology also leaves room for the use of hardware authentication. 

As the world becomes more interconnected and our lives increasingly depend on the cyber world, the increasing threat of cyberattacks and cybercrimes make it critical for us to provide better and practical training of the cybersecurity workforce. In recent years, cybersecurity competition has become one of the most effective and attractive way for educating and training college students or professionals. In this paper, we first systematically introduce in details the step-by-step procedure and technical knowledge on how we take use of the ongoing DoD cyber-range environment called Persistent Cyber Training Environment (PCTE) to set up cyber competition virtualization environment, configure and install operating systems and popular services with various well-representative vulnerabilities, and set up the participant’s access and scoring system. Then we introduce the cybersecurity competition successfully organized by us in I/ITSEC 2019 conference, and the experience and lessons learned from this real-world competition event. The technical details and knowledge presented in this paper could help other researchers and educators to set up their own cyber competition environment or event to better train the future cybersecurity workforce.