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1. Examining Penetration Tester Behavior in the Collegiate Penetration Testing Competition

   https://doi.org/10.1145/3514040  

   Meyers, Benjamin S.; Almassari, Sultan Fahad; Keller, Brandon N.; Meneely, Andrew (July 2022, ACM Transactions on Software Engineering and Methodology)

   Penetration testing is a key practice toward engineering secure software. Malicious actors have many tactics at their disposal, and software engineers need to know what tactics attackers will prioritize in the first few hours of an attack. Projects like MITRE ATT&CK™ provide knowledge, but how do people actually deploy this knowledge in real situations? A penetration testing competition provides a realistic, controlled environment with which to measure and compare the efficacy of attackers. In this work, we examine the details of vulnerability discovery and attacker behavior with the goal of improving existing vulnerability assessment processes using data from the 2019 Collegiate Penetration Testing Competition (CPTC). We constructed 98 timelines of vulnerability discovery and exploits for 37 unique vulnerabilities discovered by 10 teams of penetration testers. We grouped related vulnerabilities together by mapping to Common Weakness Enumerations and MITRE ATT&CK™. We found that (1) vulnerabilities related to improper resource control (e.g., session fixation) are discovered faster and more often, as well as exploited faster, than vulnerabilities related to improper access control (e.g., weak password requirements), (2) there is a clear process followed by penetration testers of discovery/collection to lateral movement/pre-attack. Our methodology facilitates quicker analysis of vulnerabilities in future CPTC events. 

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2. Plains Paleoindian Projectile Point Penetration Potential

   https://doi.org/10.1086/717831  

   Eren, Metin I.; Bebber, Michelle R.; Knell, Edward J.; Story, Brett; Buchanan, Briggs (March 2022, Journal of Anthropological Research)
3. Diffusiophoretic Particle Penetration into Bacterial Biofilms .

   Somasundar, A. (June 2023, ACS applied materials interfaces)

   Bacterial biofilms are communities of cells adhered to surfaces. These communities represent a predominant form of bacterial life on Earth. A defining feature of a biofilm is the three-dimensional extracellular polymer matrix that protects resident cells by acting as a mechanical barrier to the penetration of chemicals, such as antimicrobials. Beyond being recalcitrant to antibiotic treatment, biofilms are notoriously difficult to remove from surfaces. A promising, but relatively under explored approach to biofilm control, is to disrupt the extracellular polymer matrix by enabling penetration of particles to increase the susceptibility of biofilms to antimicrobials. In this work, we investigate externally imposed chemical gradients as a mechanism to transport polystyrene particles into bacterial biofilms. We show that pre-conditioning the biofilm with a pre-wash step using deionized (DI) water is essential for altering the biofilm so it takes up the micro- and nanoparticles by the application of a further chemical gradient created by an electrolyte. Using different particles and chemicals, we document the transport behavior that leads to particle motion into the biofilm and its further reversal out of the biofilm. Our results demonstrate the importance of chemical gradients in disrupting the biofilm matrix, regulating particle transport in crowded macromolecular environments, and suggest potential applications of particle transport and delivery in other physiological systems. 

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4. Evaluating Nanoparticle Penetration In Tumor Spheroids

   Bndyopadhyay, R.; Widman, J.; Suggs, L. (August 2019, 2019 BMES Conference Proceedings - REU Abstract Accepted Poster)

   Introduction: The lack of an appropriate in vitro model of the tumor microenvironment is one of the largest obstacles in evaluating preclinical cancer drug screenings.1 Cancer cell monolayers do not effectively mimic the limited drug penetration properties of the complex tumor structures found in cancer patients. 3-D multicellular tumor spheroids (MCTS) serve as a more effective model as they better resemble cancer in structure as well as limited drug penetration. In our experiments, we created heterospheroids composed of 4T1 breast tumor cells and 3T3 fibroblasts, as well as homospheroids of each cell type. Tumors feature stromal and extracellular matrix components in addition to cancer cells in ratios that vary between different types of cancer. Fibroblasts are the major component of cancer stroma as well as producers of extracellular matrix. Since heterospheroids feature 3T3 fibroblasts, they may better model the diverse tumor microenvironment.2 We also synthesized fluorescent PLGA nanoparticles that were added to our spheroid cultures. Using confocal microscopy and ImageJ’s fluorescence measuring tools, we qualitatively and quantitatively evaluated the drug penetration properties of our spheroids. 

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5. Diffusiophoretic Particle Penetration into Bacterial Biofilms

   https://doi.org/10.1021/acsami.3c03190  

   Somasundar, Ambika; Qin, Boyang; Shim, Suin; Bassler, Bonnie L.; Stone, Howard A. (July 2023, ACS Applied Materials & Interfaces)