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1. Intrinsic Run-Time Row Hammer PUFs: Leveraging the Row Hammer Effect for Run-Time Cryptography and Improved Security †

   https://doi.org/10.3390/cryptography2030013  

   Anagnostopoulos, Nikolaos; Arul, Tolga; Fan, Yufan; Hatzfeld, Christian; Schaller, André; Xiong, Wenjie; Jain, Manishkumar; Saleem, Muhammad; Lotichius, Jan; Gabmeyer, Sebastian; et al (September 2018, Cryptography)
2. Analysis of Row Hammer Attack on STTRAM

   https://doi.org/10.1109/ICCD.2018.00021  

   Khan, Mohammad Nasim; Ghosh, Swaroop (October 2018, IEEE 36th International Conference on Computer Design (ICCD))
3. Magnetic Hammer Actuation for Tissue Penetration using a Millirobot

   https://doi.org/10.1109/LRA.2017.2739805  

   Leclerc, Julien; Ramakrishnan, Ashwin; Tsekos, Nikolaos; Becker, Aaron (January 2017, IEEE Robotics and Automation Letters)

   Untethered magnetic navigation of millirobots within a human body using a magnetic resonance imaging (MRI) scanner is a promising technology for minimally invasive surgery or drug delivery. Because MRI scanners have a large static magnetic field, they cannot generate torque on magnetic millirobots and must instead use gradient-based pulling. However, gradient values are too small to produce forces large enough to penetrate tissue. This letter presents a method to produce large pulsed forces on millirobots. A ferromagnetic sphere is placed inside a hollow robot body and can move back and forth. This movement is created by alternating the magnetic gradient direction. On the posterior side, a spring allows the sphere to change direction smoothly. On the anterior side, a hard rod creates a surface for the sphere to impact. This impact results in a large pulsed force. The purpose of this study was to understand the functioning of magnetic hammer actuation and control, as well as demonstrate the viability of this mechanism for tissue penetration. This letter begins with modeling and simulating this system. Next, different control strategies are presented and tested. The system successfully penetrated lamb brain samples. Finally, preliminary tests inside a clinical MRI scanner demonstrate the potential of this actuation system. 

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4. Hammer: A Modular and Reusable Physical Design Flow Tool

   Harrison Liew; Daniel Grubb; John Wright; Colin Schmidt; Nayiri Krzysztofowicz; Adam Izraelevicz; Edward Wang; Krste Asanovic; Jonathan Bachrach; Borivoje Nikolic (January 2022, 59th Design Automation Conference)

   Process technology scaling and hardware architecture specialization have vastly increased the need for chip design space exploration, while optimizing for power, performance, and area. Hammer is an open-source, reusable physical design (PD) flow generator that reduces design effort and increases portability by enforcing a separation among design-, tool-, and process technology-specific concerns with a modular software architecture. In this work, we outline Hammer’s structure and highlight recent extensions that support both physical chip designers and hardware architects evaluating the merit and feasibility of their proposed designs. This is accomplished through the integration of more tools and process technologies—some open-source—and the designer-driven development of flow step generators. An evaluation of chip designs in process technologies ranging from 130nm down to 12nm across a series of RISC-V-based chips shows how Hammer-generated flows are reusable and enable efficient optimization for diverse applications. 

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5. Go Go Gadget Hammer: Flipping Nested Pointers for Arbitrary Data Leakage

   Tobah, Youssef; Kwong, Andrew; Kang, Ingab; Genkin, Daniel; Shin, Kang G (August 2024, Usenix Security)

   Rowhammer is an increasingly threatening vulnerability that grants an attacker the ability to flip bits in memory without directly accessing them. Despite efforts to mitigate Rowhammer via software and defenses built directly into DRAM modules, more recent generations of DRAM are actually more susceptible to malicious bit-flips than their predecessors. This phenomenon has spawned numerous exploits, showing how Rowhammer acts as the basis for various vulnerabilities that target sensitive structures, such as Page Table Entries (PTEs) or opcodes, to grant control over a victim machine. However, in this paper, we consider Rowhammer as a more general vulnerability, presenting a novel exploit vector for Rowhammer that targets particular code patterns. We show that if victim code is designed to return benign data to an unprivileged user, and uses nested pointer dereferences, Rowhammer can flip these pointers to gain arbitrary read access in the victim's address space. Furthermore, we identify gadgets present in the Linux kernel, and demonstrate an end-to-end attack that precisely flips a targeted pointer. To do so we developed a number of improved Rowhammer primitives, including kernel memory massaging, Rowhammer synchronization, and testing for kernel flips, which may be of broader interest to the Rowhammer community. Compared to prior works' leakage rate of .3 bits/s, we show that such gadgets can be used to read out kernel data at a rate of 82.6 bits/s. By targeting code gadgets, this work expands the scope and attack surface exposed by Rowhammer. It is no longer sufficient for software defenses to selectively pad previously exploited memory structures in flip-safe memory, as any victim code that follows the pattern in question must be protected. 

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