Spons & shields: practical isolation for trusted execution

Trusted execution environments (TEEs) promise a cost-effective, “lift-and-shift” solution for deploying security-sensitive applications in untrusted clouds. For this, they must support rich, multi-component applications, but a large trusted computing base (TCB) inside the TEE risks that attackers can compromise application security. Fine-grained compartmentalisation can increase security through defense-in-depth, but current solutions either run all software components unprotected in the same TEE, lack efficient shared memory support, or isolate application processes using separate TEEs, impacting performance and compatibility. We describe the Spons & Shields framework (SSF) for Intel SGX TEEs, which offers intra-TEE compartmentalisation using two new abstraction, Spons and Shields. Spons and Shields generalise process, library and user/kernel isolation inside the TEE while allowing for efficient memory sharing. When users deploy unmodified multi-component applications in a TEE, SSF dynamically creates Spons (one per POSIX process or library) and Shields (to enforce a given security policy for memory accesses). Applications can be hardened with minor code changes, e.g., by using a separate Shield to isolate an SSL library. SSF uses compiler instrumentation to protect Shield boundaries, exploiting MPX instructions if available. We evaluate SSF using a complex application service (NGINX, PHP interpreter and PostgreSQL) and show that its overhead is comparable to process isolation

CAP-VMs: Capability-based isolation and sharing in the cloud

Cloud stacks must isolate application components, while permitting efficient data sharing between components deployed on the same physical host. Traditionally, the MMU enforces isolation and permits sharing at page granularity. MMU approaches, however, lead to cloud stacks with large TCBs in kernel space, and page granularity requires inefficient OS interfaces for data sharing. Forthcoming CPUs with hardware support for memory capabilities offer new opportunities to implement isolation and sharing at a finer granularity. We describe cVMs, a new VM-like abstraction that uses memory capabilities to isolate application components while supporting efficient data sharing, all without mandating application code to be capability-aware. cVMs share a single virtual address space safely, each having only capabilities to access its own memory. A cVM may include a library OS, thus minimizing its dependency on the cloud environment. cVMs efficiently exchange data through two capability-based primitives assisted by a small trusted monitor: (i) an asynchronous read/write interface to buffers shared between cVMs; and (ii) a call interface to transfer control between cVMs. Using these two primitives, we build more expressive mechanisms for efficient cross-cVM communication. Our prototype implementation using CHERI RISC-V capabilities shows that cVMs isolate services (Redis and Python) with low overhead while improving data sharing

Hydrogen sensors on the basis of SnO2-TiO2 systems

AbstractIn this study we compare sensor responses to H2 in air using two types of sensing materials: SnO2 bulk doped with TiO2 and mechanical mixtures of SnO2 and TiO2. The materials were analyzed in the broad range of working temperatures and H2 concentrations. Thermal stability of SnO2 bulk doped with TiO2 was studied by in-situ XRD at 700°C

ORC: Increasing cloud memory density via object reuse with capabilities

Cloud environments host many tenants, and typically there is substantial overlap between the application binaries and libraries executed by tenants. Thus, memory de-duplication can increase memory density by allocating memory for shared binaries only once. Existing de-duplication approaches, however, either rely on a shared OS to de-deduplicate binary objects, which provides unacceptably weak isolation; or exploit hypervisor-based de-duplication at the level of memory pages, which is blind to the semantics of the objects to be shared. We describe Object Reuse with Capabilities (ORC), which supports the fine-grained sharing of binary objects between tenants, while isolating tenants strongly through a small trusted computing base (TCB). ORC uses hardware sup- port for memory capabilities to isolate tenants, which permits shared objects to be accessible to multiple tenants safely. Since ORC shares binary objects within a single address space through capabilities, it uses a new relocation type to create per-tenant state when loading shared objects. ORC supports the loading of objects by an untrusted guest, outside of its TCB, only verifying the safety of the loaded data. Our experiments show that ORC achieves a higher memory density with a lower overhead than hypervisor-based de-deduplication

Fate of MTBE and DCPD Compounds Relative to BTEX in Gasoline-Contaminated Aquifers

The aim of this communication is to provide preliminary results on MTBE monitoring, and at the same time to propose some new tracers of gasoline pollution in groundwater. An overview is presented on benzene-toluene-ethylbenzene-xylene (BTEX), methyl tertiary-butyl ether (MTBE), and dicyclopentadienes (DCPD) contents in gasoline formulations. Their specific fate in gasoline-contaminated aquifers are consistent with their physical-chemical properties

Vaccines in Congenital Toxoplasmosis: Advances and Perspectives

Congenital toxoplasmosis has a high impact on human disease worldwide, inducing serious consequences from fetus to adulthood. Despite this, there are currently no human vaccines available to prevent this infection. Most vaccination studies against Toxoplasma gondii infection used animal models in which the infection was established by exogenous inoculation. Here, we review recent research on potential T. gondii vaccines using animal models in which infection was congenitally established. Endeavors in this field have so far revealed that live or subunit vaccines previously found to confer protection against extrinsically established infections can also protect, at least partially, from vertically transmitted infection. Nevertheless, there is no consensus on the more adequate immune response to protect the host and the fetus in congenital infection. Most of the vaccination studies rely on the assessment of maternal systemic immune responses, quantification of parasitic loads in the fetuses, and survival indexes and/or brain parasitic burden in the neonates. More research must be carried out not only to explore new vaccines but also to further study the nature of the elicited immune protection at the maternal-fetal interface. Particularly, the cellular and molecular effector mechanisms at the maternal-fetal interface induced by immunization remain poorly characterized. Deeper knowledge on the immune response at this specific location will certainly help to refine the vaccine-induced immunity and, consequently, to provide the most effective and safest protection against T. gondii vertical infection.This work was supported by the Applied Molecular Biosciences Unit-UCIBIO, which is financed by national funds from FCT (UIDP/04378/2020 and UIDB/04378/2020). AC was supported by FCT Individual CEEC 2017 Assistant Researcher Grant 352 CEECIND/01514/2017

Impact of region-of-interest delineation methods, reconstruction algorithms, and intra- and inter-operator variability on internal dosimetry estimates using PET

Purpose Human dosimetry studies play a central role in radioligand development for positron emission tomography (PET). Drawing regions of interest (ROIs) on the PET images is used to measure the dose in each organ. In the study aspects related to ROI delineation methods were evaluated for two radioligands of different biodistribution (intestinal vs urinary). Procedures PET images were simulated from a human voxel-based phantom. Several ROI delineation methods were tested: antero-posterior projections (AP), 3D sub-samples of the organs (S), and a 3D volume covering the whole-organ (W). Inter- and intra-operator variability ROI drawing was evaluated by using human data. Results The effective dose estimates using S and W methods were comparable to the true values. AP methods overestimated (49 %) the dose for the radioligand with intestinal biodistribution. Moreover, the AP method showed the highest inter-operator variability: 11 ± 1 %. Conclusions The sub-sampled organ method showed the best balance between quantitative accuracy and inter- and intra-operator variability.Postprint (author's final draft

Southern Annular Mode-like changes in southwestern Patagonia at centennial timescales over the last three millennia

Late twentieth-century instrumental records reveal a persistent southward shift of the Southern Westerly Winds during austral summer and autumn associated with a positive trend of the Southern Annular Mode (SAM) and contemporaneous with glacial recession, steady increases in atmospheric temperatures and CO2 concentrations at a global scale. However, despite the clear importance of the SAM in the modern/future climate, very little is known regarding its behaviour during pre-Industrial times. Here we present a stratigraphic record from Lago Cipreses (51S), southwestern Patagonia, that reveals recurrent B200-year long dry/warm phases over the last three millennia, which we interpret as positive SAM-like states. These correspond in timing with the Industrial revolution, the Mediaeval Climate Anomaly, the Roman and Late Bronze Age Warm Periods and alternate with cold/wet multicentennial phases in European palaeoclimate records. We conclude that SAM-like changes at centennial timescales in southwestern Patagonia represent in-phase interhemispheric coupling of palaeoclimate over the last 3,000 years through atmospheric teleconnections.Fil: Moreno, Patricio. Universidad de Chile; ChileFil: Vilanova, Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Villa Martinez, R.. Universidad de Chile; ChileFil: Garreaud, R. D.. Universidad de Chile; ChileFil: Rojas, M.. Universidad de Chile; ChileFil: De Pol Holz, R.. Universidad de Chile; Chil

Efficacy studies of phage phiIBB-Sep1 against S. epidermidis cells under different metabolic states

Staphylococcus epidermidis has recently become known as a usual cause of nosocomial infections, predominantly in patients with indwelling medical devices. Although, S. epidermidis infections only rarely develop into life-threatening diseases, they are very frequent and difficult to treat due to the ability of this bacterium to adhere to the surfaces of indwelling medical devices and form biofilms. When S. epidermidis cells are in a biofilm they are more resistant to antibiotics and to the immune system. The importance of biofilms in the pathogenesis of the S. epidermidis infections is becoming more understandable, consequently several studies are needed, in order to develop effective methods for biofilm control. The use of bacteriophages (phages) to eradicate biofilms can be seen as a potentially valuable approach. Phages are virus that infect bacteria and are the most abundant organisms on Earth. They are generally very efficient antibacterial agents and possess many advantages over antibiotics. Our aim is to search for virulent phages with broad host range for S. epidermidis biofilm therapy. Using wastewater treatment plants raw effluents we were able to isolate 5 phages. Their lytic activity was screened against 40 clinical S. epidermidis isolates with different genetic profiles and it was found to be different ranging from 46% to 95% of positive results. Further morphologic and genetic characterization of these isolated phages is now being performed. Efficacy studies results show that phage phiIBB-Sep1 is able to cause a 6 Log CFU/ml reduction of the cell titre in <2h for some of the clinical strains at exponential phase and in <4h for stationary phase cells (using a MOI of 1). This phage has also the capacity of reducing by up to 2 Log CFU/ml 24h biofilm cells and in some strains it was observed 50% cell reduction on biofilms. Besides CFU counting, all the cell counts were confirmed by flow cytometry assays. Additionally, flow cytometry allow the observation that this phage kill cells under different metabolic states from the biofilm. Work developed with non biofilm forming strains showed that possibly PNAG might be the cell receptor of the phage. The high amounts of PNAG on biofilms, might the lower activity of this phage on biofilms. These are promising results, since phage phiIBB-Se1 presents a broad host range and ability to control S. epidermidis under different metabolic states. Ongoing studies are being performed with 4 other phages, with the purpose of developing a phage cocktail to be used against S. epidermidis biofilm infections