Attack Surface Expansion through Decoy Trap for Protected Servers in Moving Target Defense

Tae-Keun Park(박태근),Kyung-Min Park(박경민),Dae-Sung Moon(문대성) 한국컴퓨터정보학회 2019 韓國컴퓨터情報學會論文誌 Vol.24 No.10

본 논문에서는 보호대상 서버 네트워크에 디코이 트랩을 통한 공격 표면 확장의 적용 방법을 제안한다. 보호대상 서버 네트워크는 많은 수의 디코이들과 보호대상 서버로 구성되며, 각 보호대상 서버는 Hidden Tunner Networking이라는 네트워크 기반 이동 표적 방어 기법에 따라 IP 주소와 포트 번호를 변이한다. 이동 표적 방어는 공격을 막기 위하여 지속적으로 시스템의 공격 표면을 변경하는 사이버 보안에서의 새로운 접근방법이다. 공격 표면 확장은 공격을 막기 위해 디코이와 디코이 그룹을 활용하는 접근방법이다. 제안하는 방법에서는 공격자가 디코이 트랩에서 공격자의 모든 시간과 노력을 허비하도록 커스텀 체인과 RETURN 타켓을 사용하여 보호대상 서버의 NAT 테이블을 수정한다. 본 논문에서는 제안하는 방법이 적용되기 전과 후에 보호대상 서버 네트워크에서의 공격자 성공률을 수식으로 계산한다. 제안하는 방법은 보호대상 서버가 공격자에 의해 식별되고 공격당할 확률을 현저히 줄일 것으로 기대된다. In this paper, we propose a method to apply the attack surface expansion through decoy traps to a protected server network. The network consists of a large number of decoys and protected servers. In the network, each protected server dynamically mutates its IP address and port numbers based on Hidden Tunnel Networking that is a network-based moving target defense scheme. The moving target defense is a new approach to cyber security and continuously changes system’s attack surface to prevent attacks. And, the attack surface expansion is an approach that uses decoys and decoy groups to protect attacks. The proposed method modifies the NAT table of the protected server with a custom chain and a RETURN target in order to make attackers waste all their time and effort in the decoy traps. We theoretically analyze the attacker success rate for the protected server network before and after applying the proposed method. The proposed method is expected to significantly reduce the probability that a protected server will be identified and compromised by attackers.

Performance of a hydrofoil operating close to a free surface over a range of angles of attack

Ni Zao,Dhanak Manhar,Su Tsung-chow 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Performance of a NACA 634-021 hydrofoil in motion under and in close proximity of a free surface for a large range of angles of attack is studied. Lift and drag coefficients of the hydrofoil at different submergence depths are investigated both numerically and experimentally, for 0 AoA30 at a Reynolds number of 105. The results of the numerical study are in good agreement with the experimental results. The agreement confirms the new finding that for a submerged hydrofoil operating at high angles of attack close to a free surface, the interaction between the hydrofoil-motion induced waves on the free surface and the hydrofoil results in mitigation of the flow separation characteristics on the suction side of the foil and delay in stall, and improvement in hydrofoil performance. In comparing with a baseline case, results suggest a 55% increase in maximum lift coefficient and 90% average improvement in performance for, based on the lift-to-drag ratio, but it is also observed significant decrease of lift-to-drag ratio at lower angles of attack. Flow details obtained from combined finite volume and volume of fluid numerical methods provide insight into the underlying enhancement mechanism, involving interaction between the hydrofoil and the free surface.

Numerical technique for chloride ingress with cover concrete property and time effect

Lee, Bang Yeon,Ismail, Mohamed A.,Kim, Hyeok-Jung,Yoo, Sung-Won,Kwon, Seung-Jun TECHNO-PRESS 2017 COMPUTERS AND CONCRETE Vol.20 No.2

Durability problems initiated from steel corrosion are unseen but critical issues, so that many researches are focused on chloride penetration evaluation. Even if RC (Reinforced Concrete) structures are exposed to normal environment, chloride ingress varies with concrete surface conditions and exposed period. This paper presents an analysis technique for chloride behavior evaluation considering time effect on diffusion and surface conditions assumed as double-layered system. For evaluation of deteriorated surface condition, field investigation was performed for concrete pavement exposed to deicing agent for 18 years. In order to consider enhanced surface concrete, chloride profiles in surface-impregnated concretes exposed to chloride attack for 2 years from previous research were investigated. Through reverse analysis, effectively deteriorated/enhanced depth of surface and the related reduced/enlarged diffusion coefficient in the depth are simulated. The proposed analysis technique was evaluated to handle the chloride behavior more accurately considering changes of chloride ingress within surface layer and decreased diffusion coefficient with time. For the concrete surface exposed to deicing agent, the deteriorated depth and enlarged diffusion coefficient are evaluated to be 12.5~15.0 mm and 200% increasing diffusion coefficient, respectively. The results in concrete containing enhanced cover show 10.0~12.5 mm of impregnated depth and 85% reduction of chloride diffusion in tidal and submerged conditions.

Numerical technique for chloride ingress with cover concrete property and time effect

이방연,Mohamed A. Ismail,김혁정,유성원,권성준 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.2

Durability problems initiated from steel corrosion are unseen but critical issues, so that many researches are focused on chloride penetration evaluation. Even if RC (Reinforced Concrete) structures are exposed to normal environment, chloride ingress varies with concrete surface conditions and exposed period. This paper presents an analysis technique for chloride behavior evaluation considering time effect on diffusion and surface conditions assumed as double-layered system. For evaluation of deteriorated surface condition, field investigation was performed for concrete pavement exposed to deicing agent for 18 years. In order to consider enhanced surface concrete, chloride profiles in surface-impregnated concretes exposed to chloride attack for 2 years from previous research were investigated. Through reverse analysis, effectively deteriorated/ enhanced depth of surface and the related reduced/enlarged diffusion coefficient in the depth are simulated. The proposed analysis technique was evaluated to handle the chloride behavior more accurately considering changes of chloride ingress within surface layer and decreased diffusion coefficient with time. For the concrete surface exposed to deicing agent, the deteriorated depth and enlarged diffusion coefficient are evaluated to be 12.5~15.0 mm and 200% increasing diffusion coefficient, respectively. The results in concrete containing enhanced cover show 10.0~12.5 mm of impregnated depth and 85% reduction of chloride diffusion in tidal and submerged conditions.

Effectiveness of fibers and binders in high-strength concrete under chemical corrosion

Mahdi Nematzadeh,Saber Fallah-Valukolaee 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.2

Investigating the properties and durability of high-strength concrete exposed to sulfuric acid attack for the purpose of its application in structures exposed to this acid is of outmost importance. In this research, the resistance and durability of highstrength concrete containing macro-polymeric or steel fibers together with the pozzolans of silica fume or nano-silica against sulfuric acid attack are explored. To accomplish this goal, in total, 108 high-strength concrete specimens were made with 9 different mix designs containing macro-polymeric and steel fibers at the volume fractions of 0.5, 0.75, and 1.0%, as well as the pozzolans of silica fume and nano-silica with the replacement levels of 10 and 2%, respectively. After placing the specimens inside a 5% sulfuric acid solution in the periods of 7, 21, and 63 days of immersion, the effect of adding the fibers and pozzolans on the compressive properties, ultrasonic pulse velocity (UPV), and weight loss of high-strength concrete was investigated and the respective results were compared with those of the reference specimens. The obtained results suggest the dependency of the resistance and durability loss of high-strength concrete against sulfuric acid attack to the properties of fibers as well as their fraction in concrete volume. Moreover, compared with using nano-silica, using silica fume in the fibrous concrete mix leads to more durable specimens against sulfuric acid attack. Finally, an optimum solution for the design parameters where the crushing load of high-strength fibrous concrete is maximized was found using response surface method (RSM).

전산 기법을 이용한 공대공 유도 미사일의 고앙각 공력특성 예측

노국현(K.H. Noh),정기영(K.Y. Jung),명노신(R.S. Myong),박정호(J.H. Park) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

Efficient prediction of aerodynamic characteristics remains important in the preliminary design stage of missile. In particular unexpected side force and yawing moment can occur by asymmetric vortex in air-to-air missiles with slender shaped body at high angle of attack. In this study, a CFD code based on the Navier-Stokes equations was used to calculate the flowfields at high angle of attack, while a semi-empirical method was used at low angle of attack. It was shown that side force and yawing moment at high angle of attack can be predicted with reasonable accuracy by a CFD method based on the concept of applying different surface roughness in forebody.

세장형 물체 주의 고앙각 유동의 비대칭 와류 및 측력 특성에 관한 수치적 연구

정성기(S.K. Jung),정재홍(J.H. Jung),명노신(R.S. Myong),조태환(T.H. Cho) 한국전산유체공학회 2006 한국전산유체공학회지 Vol.11 No.3

Flow around a guided missile in high maneuver. i.e. at a high angle of attack. shows complex phenomena. It is well known that even in geometrically symmetric conditions the flow around a missile at high angles of attack can generate unexpected large side forces and yaw moments due to asymmetric vortices. In this paper, a CFD code (FLUENT) based on the Navier-Stokes equations was used for the numerical analysis to find a suitable numerical mechanism for generation of asymmetric vortices. It is shown that a numerical technique of applying different surface roughness to a specific area of the missile nose surface gives the best fit in comparison with the experimental results. In addition, a numerical investigation of variations of side forces and pressure distributions with angle of attack and roll angle was conducted for the purpose of identifying the source of vortex asymmetries.

An Approach for Applying Network-based Moving Target Defense into Internet of Things Networks

Tae-Keun Park(박태근),Kyung-Min Park(박경민),Dae-Sung Moon(문대성) 한국컴퓨터정보학회 2019 韓國컴퓨터情報學會論文誌 Vol.24 No.9

In this paper, we propose an approach to apply network-based moving target defense into Internet of Things (IoT) networks. The IoT is a technology that provides the high interconnectivity of things like electronic devices. However, cyber security risks are expected to increase as the interconnectivity of such devices increases. One recent study demonstrated a man-in-the-middle attack in the statically configured IoT network. In recent years, a new approach to cyber security, called the moving target defense, has emerged as a potential solution to the challenge of static systems. The approach continuously changes system’s attack surface to prevent attacks. After analyzing IPv4 / IPv6-based moving target defense schemes and IoT network-related technologies, we present our approach in terms of addressing systems, address mutation techniques, communication models, network configuration, and node mobility. In addition, we summarize the direction of future research in relation to the proposed approach.

수소취화된 인코넬 718의 VHCF(Very High Cycle Fatigue) 피로특성에 관한 연구

서창민(Chang-Min Suh),남승훈(Seung-Hoon Nahm),김준형(Jun-Hyong Kim),편영식(Young-Sik Pyun) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.7

실온에서 인코넬 718의 UNSM(Ultrasonic nanocrystal surface modification)처리재, 수소취화재(100 bar, 300 ℃에서 120 h) 및 수소취화재의 UNSM처리재의 회전굽힘피로시험에 의해 얻어진 결과, 수소취화재는 미처리재의 S-N곡선보다 피로수명이 약 10~20 % 감소하며 부식피로나 비철재료처럼 피로한도 없이 점진적으로 감소하였다. 표면균열수는 수소취화의 영향으로 평균입경(13 μm)보다 작은 균열의 비율이 약 80 %를 차지하였다. 결정입계, 표면 흠 등에 수소침투에 의한 취화현상으로 티어링(tearing)하면서 복수로 발생한 작은 표면균열은 불규칙적으로 분포하며 티어링하면서 성장, 합체되어 피로수명이 감소하는 것으로 추정된다. 미처리재에 비해서 UNSM처리재의 피로수명은 전 영역에서 크게 증가하였고, 수소취화된 시험편을 UNSM 처리한 후 피로시험을 실시하면 700 MPa에서 10배 이상, 600 MPa에서 20배 이상 증가하였다. This study is to investigate the influence of hydrogen attack and UNSM on fatigue behaviors of the Inconel 718 alloy. The decrease of the fatigue life between the untreated and the hydrogen attacked material is 10-20%. The fatigue lives of hydrogen attacked specimen decreased without a fatigue limit, similar to those of nonferrous materials. Due to hydrogen embrittlement, about 80% of the surface cracks were smaller than the average grain size of 13 μm. Many small surface cracks caused by the embrittling effect of hydrogen attack were initiated at the grain boundaries and surface scratches. Cracks were irregularly distributed, grew, and then coalesced through tearing, leading to a reduction of fatigue life. Results revealed that the fatigue lives of UNSM-treated specimens were longer than those of the untreated specimens.

A novel approach for analyzing the nuclear supply chain cyber-attack surface

Eggers, Shannon Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

The nuclear supply chain attack surface is a large, complex network of interconnected stakeholders and activities. The global economy has widened and deepened the supply chain, resulting in larger numbers of geographically dispersed locations and increased difficulty ensuring the authenticity and security of critical digital assets. Although the nuclear industry has made significant strides in securing facilities from cyber-attacks, the supply chain remains vulnerable. This paper discusses supply chain threats and vulnerabilities that are often overlooked in nuclear cyber supply chain risk analysis. A novel supply chain cyber-attack surface diagram is provided to assist with enumeration of risks and to examine the complex issues surrounding the requirements for securing hardware, firmware, software, and system information throughout the entire supply chain lifecycle. This supply chain cyber-attack surface diagram provides a dashboard that security practitioners and researchers can use to identify gaps in current cyber supply chain practices and develop new risk-informed, cyber supply chain tools and processes.