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This paper proposes a novel compact tri-band bandpass filter based on two coupled asymmetrical stub-loaded resonators (ASLR). The proposed filter can achieve three resonant frequencies by tuning uniform impedance line, short-circuit stub, and open-circuit stub, respectively. In addition, the asymmetrical stub can be loaded at any position of the main branch, which will facilitate the circuit design for no impedance of special ratio is needed, and the design bound can be alleviated. Meanwhile, thanks to its simple structure, the whole filter occupies an area of 0.021 λg2 based on RO4350B substrate, much smaller than other similar tri-band filters. Measurement results show that the filter achieves fractional bandwidths (FBW) of 7.5%, 6.4% and 4.2%, respectively for three bands. The proposed filter is small and can achieve a high-frequency selectivity at 2.45 GHz, 3.5 GHz and 5.25 GHz, corresponding to Bluetooth, World Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN), respectively. The proposed filter will find a wide application in wireless communications thanks to its attractive advantages. [ABSTRACT FROM AUTHOR]

This paper examines the security provided by different implementations of Address Space Layout Randomization (ASLR). ASLR is a security mechanism that increases control-flow integrity by making it more difficult for an attacker to properly execute a buffer-overflow attack, even in systems with vulnerable software. The strength of ASLR lies in the randomness of the offsets it produces in memory layouts. We compare multiple operating systems, each compiled for two different hardware architectures, and measure the amount of entropy provided to a vulnerable application. Our paper is the first publication that we are aware of that quantitatively compares the entropy of different ASLR implementations. In addition, we provide a method for remotely assessing the efficacy of a particular security feature on systems that are otherwise unavailable for analysis, and highlight the need for independent evaluation of security mechanisms.

In current software environments, code injection attacks have been better defended. But it also forced attackers to use the code already exist in memory to construct code-reuse attack, making code-reuse attack become the focal point of the new round of offensive and defensive games. As an important defense against attacks based on address space layout, code randomization technology effectively defends code-reuse attack by randomizing memory address space. The ASLR proposed by the Pax team is now used by most operating systems. However, due to memory disclosure, the security premise of code randomization has been broken. Therefore, in order to effectively defend against code-reuse attack, the current code randomization technology needs to improve the ability to resist memory disclosure. This paper mainly discusses the current randomization scheme in the context of memory disclosure and summarizes the future development direction of current code randomization technology.

Program vulnerabilities are a serious security threat. It is important to develop defenses preventing their exploitation, especially with a rapid increase of ROP attacks. State of the art defenses have some drawbacks that can be used by attackers. In this paper we propose fine-grained address space layout randomization on program load that is able to protect from such kind of attacks. During the static linking stage executable and library files are supplemented with information about function boundaries and relocations. A system dynamic linker/loader uses this information to perform functions permutation. The proposed method was implemented for 64-bit programs on CentOS 7 operating system. The implemented method has shown good resistance to ROP attacks based on two metrics: the number of survived gadgets and the exploitability estimation of ROP chain examples. The implementation presented in this article is applicable across the entire operating system and has shown 1.5 % time overhead. The working capacity of proposed approach was demonstrated on real programs. The further research can cover forking randomization and finer granularity than on the function level. It also makes sense to implement the randomization of short functions placement, taking into account the relationships between them. The close arrangement of functions that often call each other can improve the performance of individual programs.

Memory errors are still a serious threat affecting millions of devices worldwide. Recently, bounty programs have reached a new record, paying up to USD 2.5 million for one single vulnerability in Android and up to USD 2 million for Apple’s operating system. In almost all cases, it is common to exploit memory errors in one or more stages to fully compromise those devices. In this paper, we review and discuss the importance of memory error vulnerabilities, and more specifically stack buffer overflows to provide a full view of how memory errors are exploited. We identify the root causes that make those attacks possible on modern x86-64 architecture in the presence of modern protection techniques. We have analyzed how unsafe library functions are prone to buffer overflows, revealing that although there are secure versions of those functions, they are not actually preventing buffer overflows from happening. Using secure functions does not result in software free from vulnerabilities and it requires developers to be security-aware. To overcome this problem, we discuss the three main security protection techniques present in all modern operating system; the non-eXecutable bit (NX), the Stack Smashing Protector (SSP) and the Address Space Layout Randomization (ASLR). After discussing their effectiveness, we conclude that although they provide a strong level of protection against classical exploitation techniques, modern attacks can bypass them.

Abstract: Software vulnerabilities are a serious security threat. It is important to develop protection mechanisms preventing their exploitation, especially with a rapid increase of ROP attacks. State of the art protection mechanisms have some drawbacks that can be used by attackers. In this paper, we propose fine-grained address space layout randomization on program load that is able to protect from such kind of attacks. During the static linking stage, the executable and library files are supplemented with information about function boundaries and relocations. A system dynamic linker/loader uses this information to perform permutation of functions. The proposed method was implemented for 64-bit programs on CentOS 7 operating system. The implemented method has shown good resistance to ROP attacks evaluated by two metrics: the number of survived gadgets and the exploitability estimation of ROP chain examples. The implementation presented in this article is applicable across the entire operating system and has no compatibility problems affecting the program performance. The working capacity of proposed approach was demonstrated on real programs. The further research can cover forking randomization and finer granularity than on the function level. It also makes sense to implement the randomization of short functions placement taking into account the relationships between them. The close arrangement of functions that often call each other can improve the performance of individual programs. [ABSTRACT FROM AUTHOR]

Background The Active Straight Leg Raise is a functional test used in the assessment of pelvic girdle pain, and has shown to have good validity, reliability and responsiveness. The Active Straight Leg Raise is considered to examine the patients' ability to transfer load through the pelvis. It has been hypothesized that patients with pelvic girdle pain lack the ability to stabilize the pelvic girdle, probably due to instability or increased movement of the sacroiliac joint. This study examines the movement of the sacroiliac joints during the Active Straight Leg Raise in patients with pelvic girdle pain. Methods Tantalum markers were inserted in the dorsal sacrum and ilium of 12 patients with long-lasting pelvic girdle pain scheduled for sacroiliac joint fusion surgery. Two to three weeks later movement of the sacroiliac joints during the Active Straight Leg Raise was measured with radiostereometric analysis. Findings Small movements were detected. There was larger movement of the sacroiliac joint of the rested leg's sacroiliac joint compared to the lifted leg's side. A mean backward rotation of 0.8° and inward tilt of 0.3° were seen in the rested leg's sacroiliac joint. Interpretation The movements of the sacroiliac joints during the Active Straight Leg Raise are small. There was a small backward rotation of the innominate bone relative to sacrum on the rested leg's side. Our findings contradict an earlier understanding that a forward rotation of the lifted leg's innominate occur while performing the Active Straight Leg Raise. [ABSTRACT FROM AUTHOR]

Background: Hamstring length assessment has an important value in Physiotherapy assessment and better outcome of patients. Purpose of the study was 1) To compare Active SLR and Active knee extension test values as per Kendall’s muscle-range assessment, 2) To compare Passive SLR and Passive knee extension test values as per Kendall’s muscle range assessment. Methods: Total 100 healthy individuals (age 20.83±1.17, 14 males, 86 females) participated in study. Goniometric assessment of hip flexion-extension and knee flexion was assessed followed by active and passive straight leg raising (ASLR and PSLR) and knee extension tests (AKE and PKE). Kendall’s formula was used to find hamstring muscle-range. ASLR and AKE results were compared for means and correlation was assessed. PSLR and PKE results were compared for means and correlation was assessed. Result: The average hamstring-range is about 79.34% (ASLR), 83.67% (PSLR), 77.92% (AKE), and 81.43% (PKE) of total joint range of hamstrings. There is significant difference between ASLR and AKE values and between PSLR and PKE values. Conclusion: Total hamstring excursion in all methods confirms Kendall’s statement. However difference between SLR and knee extension tests suggest that SLR values of hamstrings length and knee extension values of hamstrings length cannot be used interchangeably. Other mechanical factors may play role for the difference between these values. Implications: Sequence of Hip flexion and Knee extension for hamstring length assessment has a significant effect on results and it should be considered by therapist before clinical decision making.

Las técnicas de ataque a aplicaciones por corrupción de memoria aprovechan las debilidades de los programas para obtener ejecución de código arbitrario. Estos fallos de programación han sido utilizados por diferentes ataques desde la década de los ochenta. Este documento presenta las diferentes técnicas que puede utilizar un atacante para lograr su objetivo y las precauciones que debe tener un desarrollador de aplicaciones, para evitar que su programa esté expuesto a vulnerabilidades que permitan ejecutar ataques por corrupción de memoria. Los fabricantes de sistemas operativos y compiladores introdujeron diferentes mecanismos de defensa para proteger las aplicaciones. Estos mecanismos no son excluyentes y cada uno tiene sus propios objetivos de diseño para añadir nuevas capas de seguridad.Attack techniques against memory corruption applications take advantage of the programs weakness for obtaining execution of arbitrary code. These programming failures have been used for several attacks since the 80's. This document shows several techniques to be used by an attacker in order to achieve his objectives and the precautions an application developer should have for preventing the program to be exposed vulnerable situations which may allow having attacks for memory corruption. Manufacturers of operating systems and compilers introduced several defense mechanisms to protect applications. These are not excluding mechanisms and each one of them has its own design objectives for adding new security layers.

Protecting critical systems and assets against cyberattacks is an ever more difficult challenge that strongly favors attackers. Whereas defenders must protect a large, diverse set of cybersystems containing an unknown number of vulnerabilities of various types, attackers need only find one or a few exploitable vulnerabilities to mount a successful attack. One promising approach that can shift the balance in the defenders' favor is to create uncertainty for attackers by dynamically changing system properties in what is called a cyber moving target (MT). MT techniques seek to randomize system components to reduce the likelihood of a successful attack, add dynamics to a system to reduce the lifetime of an attack, and diversify otherwise homogeneous collections of systems to limit the damage of a large-scale attack. In this article, the authors review the five dominant domains of MT techniques available today as research prototypes and commercial solutions. They present the techniques' strengths and weaknesses and make recommendations for future research that will improve current capabilities. [ABSTRACT FROM PUBLISHER]

Attack techniques against memory corruption applications take advantage of the programs weakness for obtaining execution of arbitrary code. These programming failures have been used for several attacks since the 80's. This document shows several techniques to be used by an attacker in order to achieve his objectives and the precautions an application developer should have for preventing the program to be exposed vulnerable situations which may allow having attacks for memory corruption. Manufacturers of operating systems and compilers introduced several defense mechanisms to protect applications. These are not excluding mechanisms and each one of them has its own design objectives for adding new security layers. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this cross-sectional study was to explore the associations between pain locations, responses to the posterior pelvic pain provocation (P4) test, responses to the active straight leg raise (ASLR) test and disability in late pregnancy. 283 women in gestation week 30 (mean age 31.3 years; 59% nullipara) completed a questionnaire (including pain drawing and Disability Rating Index, DRI). A physiotherapist blinded for the questionnaire data assessed responses to the P4 and ASLR tests. The pain drawing was used to: 1) distinguish between Pelvic girdle pain (PGP) and low back pain (LBP); 2) discriminate between pain locations within the pelvic area. A large variation was found in DRI within each pain location group. Women with PGP were more afflicted than the women with LBP and those without PGP. Highest DRI score was reported by women having combined symphysis pain and bilateral posterior pain. The multivariate analyses showed that results from P4 and ASLR contributed independently to DRI. Taken together, pain location combined with responses to P4 and ASLR tests are relevant when evaluating affliction in pregnant women with possible PGP. [Copyright &y& Elsevier]

Memory errors are still a serious threat affecting millions of devices worldwide. Recently, bounty programs have reached a new record, paying up to USD 2.5 million for one single vulnerability in Android and up to USD 2 million for Apple's operating system. In almost all cases, it is common to exploit memory errors in one or more stages to fully compromise those devices. In this paper, we review and discuss the importance of memory error vulnerabilities, and more specifically stack buffer overflows to provide a full view of how memory errors are exploited. We identify the root causes that make those attacks possible on modern x86-64 architecture in the presence of modern protection techniques. We have analyzed how unsafe library functions are prone to buffer overflows, revealing that although there are secure versions of those functions, they are not actually preventing buffer overflows from happening. Using secure functions does not result in software free from vulnerabilities and it requires developers to be security-aware. To overcome this problem, we discuss the three main security protection techniques present in all modern operating system; the non-eXecutable bit (NX), the Stack Smashing Protector (SSP) and the Address Space Layout Randomization (ASLR). After discussing their effectiveness, we conclude that although they provide a strong level of protection against classical exploitation techniques, modern attacks can bypass them. [ABSTRACT FROM AUTHOR]

The major weakness of address space layout randomization is the address space of the program being randomized only once at loading. Therefore, it cannot prevent those advanced code reuse attacks, such as just-in-time return-oriented programming. In view of this situation, we propose an instantaneous and continual address space rerandomization approach, called just-in-time address space rerandomization (JIT-ASR) to thwart the attack. The JIT-ASR uses the virtual memory management and can ceaselessly change the program's address space by modifying the virtual page number of the code address and page table at runtime. In this way, the address space of the program will change continually. This mechanism will make the addresses used by the attacker become stale, and the attack payload cannot be performed successfully. To demonstrate the effectiveness and efficiency of JIT-ASR, we apply it to SPEC CPU2006 benchmark suite. The evaluation results and security analysis show that JIT-ASR can resist the code reuse attacks, especially just-in-time return-oriented programming, and yield low runtime performance overhead (1.2% on average on the SPEC CPU2006 benchmark). [ABSTRACT FROM AUTHOR]

Moving-target technologies can significantly raise the bar for attackers even without requiring that the distribution of vulnerabilities in the underlying systems be reduced. These techniques should be essential tools for every system architect. [ABSTRACT FROM PUBLISHER]

Any added complexity in a software system will increase the possible program states, introducing a larger attack surface and the possibility of more exploitable flaws. JIT engines, however, alter the environment in which they execute in far more interesting ways, not only through implementation flaws but also by their fundamental operation modes. [ABSTRACT FROM PUBLISHER]

Smartphones' features are great, but with the power they provide, there's also a threat. Smartphones are becoming a target of attackers in the same way PCs have been for many years. This article examines the security models of two popular smart phone operating systems: Apple's iOS and Google's Android. [ABSTRACT FROM PUBLISHER]