Taejoon Park

Behavioral detection of malware on mobile handsets

A novel behavioral detection framework is proposed to detect mobile worms, viruses and Trojans, instead of the signature-based solutions currently available for use in mobile devices. First, we propose an efficient representation of malware behaviors based on a key observation that the logical ordering of an applications actions over time often reveals the malicious intent even when each action alone may appear harmless. Then, we generate a database of malicious behavior signatures by studying more than 25 distinct families of mobile viruses and worms targeting the Symbian OS - the most widely-deployed handset OS - and their variants. Next, we propose a two-stage mapping technique that constructs these signatures at run-time from the monitored system events and API calls in Symbian OS. We discriminate the malicious behavior of malware from the normal behavior of applications by training a classifier based on Support Vector Machines (SVMs). Our evaluation on both simulated and real-world malware samples indicates that behavioral detection can identify current mobile viruses and worms with more than 96% accuracy. We also find that the time and resource overheads of constructing the behavior signatures from low-level API calls are acceptably low for their deployment in mobile devices.

LiSP: A lightweight security protocol for wireless sensor networks

Small low-cost sensor devices with limited resources are being used widely to build a self-organizing wireless network for various applications, such as situation monitoring and asset surveillance. Making such a sensor network secure is crucial to their intended applications, yet challenging due to the severe resource constraints in each sensor device. We present a lightweight security protocol (LiSP) that makes a tradeoff between security and resource consumption via efficient rekeying. The heart of the protocol is the novel rekeying mechanism that offers (1) efficient key broadcast without requiring retransmission/ACKs, (2) authentication for each key-disclosure without incurring additional overhead, (3) the ability of detecting/recovering lost keys, (4) seamless key refreshment without disrupting ongoing data encryption/decryption, and (5) robustness to inter-node clock skews. Furthermore, these benefits are preserved in conventional contention-based medium access control protocols that do not support reliable broadcast. Our performance evaluation shows that LiSP reduces resource consumption significantly, while requiring only three hash computations, on average, and a storage space for eight keys.

Soft tamper-proofing via program integrity verification in wireless sensor networks

Small low-cost sensor devices, each equipped with limited resources, are networked and used for various critical applications, especially those related to homeland security. Making such a sensor network secure is challenging mainly because it usually has to operate in a harsh, sometimes hostile, and unattended environment, where it is subject to capture, reverse-engineering, and manipulation. To address this challenge, we present a program-integrity verification (PIV) protocol that verifies the integrity of the program residing in each sensor device whenever the device joins the network or has experienced a long service blockage. The heart of PIV is the novel randomized hash function tailored to low-cost CPUs, by which the algorithm for hash computation on the program can be randomly generated whenever the program needs to be verified. By realizing this randomized hash function, the PlV protocol 1) prevents manipulation/reverse-engineering/reprogramming of sensors unless the attacker modifies the sensor hardware (e.g., attaching more memory), 2) provides purely software-based protection, and 3) triggers the verification infrequently, thus incurring minimal intrusiveness into normal sensor functions. Our performance evaluation shows that the PIV protocol is computationally efficient and incurs only a small communication overhead, hence making it ideal for use in low-cost sensor networks.

A Survey of Security Threats on 4G Networks

Many communication societies such as ITU and IEEE are working on 4th generation (4G) communication. This paper provides an overview of standardization activities focusing on the network security architectures and a survey of security threats on 4G networks. Our survey shows that a number of new security threats to cause unexpected service interruption and disclosure of information will be possible in 4G due mainly to the fact that 4G is an IP-based, heterogeneous network. We also found there still remain several open issues although many are working on fixing and/or designing new security architectures for 4G.

Energy-Efficient Approximate Multiplication for Digital Signal Processing and Classification Applications

The need to support various digital signal processing (DSP) and classification applications on energy-constrained devices has steadily grown. Such applications often extensively perform matrix multiplications using fixed-point arithmetic while exhibiting tolerance for some computational errors. Hence, improving the energy efficiency of multiplications is critical. In this brief, we propose multiplier architectures that can tradeoff computational accuracy with energy consumption at design time. Compared with a precise multiplier, the proposed multiplier can consume 58% less energy/op with average computational error of

Analyzing the Impact of Joint Optimization of Cell Size, Redundancy, and ECC on Low-Voltage SRAM Array Total Area

\sim 1

Numerical Simulation of Time‐dependent Spring‐back Behavior for Aluminum Alloy 6022‐T4 Sheet

%. Finally, we demonstrate that such a small computational error does not notably impact the quality of DSP and the accuracy of classification applications.

Maximizing responsiveness of touch sensing via charge multiplexing in touchscreen devices

The increasing power consumption of processors has made power reduction a first-order priority in processor design. Voltage scaling is one of the most powerful power-reduction techniques introduced to date, but is limited to some minimum voltage VDDMIN. Below VDDMIN on-chip SRAM cells cannot all operate reliably due to increased process variability with technology scaling. The use of larger SRAM cells, which are less sensitive to process variability, allows a reduction in VDDMIN. However, since the large-scale memory structures such as last-level caches (LLCs) often determine the VDDMIN of processors, these structures cannot afford to use large SRAM cells due to the resulting increase in die area. In this paper we first propose a joint optimization of LLC cell size, the number of redundant cells, and the strength of error-correction coding (ECC) to minimize total SRAM area while meeting yield and VDDMIN targets. The joint use of redundant cells and ECC enables the use of smaller cell sizes while maintaining design targets. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. In 32-nm technology our joint approach yields a 27% reduction in total SRAM area (including the extra cells) when targeting 90% yield and 600 mV VDDMIN. Second, we demonstrate that the ECC used to repair defective cells can be combined with a simple architectural technique, which can also fix particle-induced soft errors, without increasing ECC strength or processor runtime.

ReLiSCE: Utilizing Resource-Limited Sensors for Office Activity Context Extraction

In order to analyze the time‐dependent spring‐back behavior of the aluminum alloy 6022‐T4 sheet, the viscoelastic/plastic constitutive law was applied by utilizing a linear viscoelastic/plastic model previously developed. As for the plastic deformation, the combined isotropic‐kinematic hardening law was used to represent the Bauschinger behavior and transient hardening, while a non‐quadratic anisotropic yield function, Yld2000‐2d, was applied to account for anisotropic yield behavior. The numerical formulation was developed based on the incremental deformation viscoelastic/plasticity theory and then, the constitutive law was implemented into the ABAQUS/Standard commercial finite element program using the user‐defined material subroutine, UMAT. The viscoelastic behavior was characterized by the creep test above the initial yield stress level, while anisotropic yielding and hardening parameters were obtained by the uniaxial tensile test. The constitutive law and the formulation were successfully validated f...

Kintense: a robust, accurate, real-time and evolving system for detecting aggressive actions from streaming 3D skeleton data

This paper presents a novel touch sensing scheme for capacitive touchscreen devices that is capable of maximizing the responsiveness of touch sensing, thereby enabling the realization of high-speed/resolution touchscreens. The heart of our proposed scheme is to measure various combinations of channels of the touchscreen in a way to preserve orthogonality among channels, and to detect the presence of touch by decomposing the measurements into orthogonal components. After designing the measurement and detection algorithms in detail, we demonstrate via simulation that our proposed scheme indeed works.