• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.827-838
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• 2018

Since 2014, ease of regulations on financial institutions expanded the mobile payment market based on simple authentication, and this resulted in the emergence of various simple payment services. Although several security solutions have been used to mitigate possible security threats to payment applications, there are vulnerabilities which can still be found due to the structure in which the security solution is applied to the payment service. In this paper, we analyze the payment application and security solution from the process perspective, and prove through experimentation that verification functions of security solutions can be bypassed without detailed analysis of each security function, but by simply manipulating the verification result value. Finally, we propose methods to mitigate the bypass method presented in this paper from three different perspectives, and thereby contribute to the improvement of security level of the payment service.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.10
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• pp.445-460
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• 2013

Mobile applications today are being offered as various services depending on the mobile device and mobile environment of users. This increase in mobile applications has shifted the spotlight to their vulnerability. As an effective method of security verification, this paper proposes "phase-wise security verification for the implementation of mobile applications". This method allows additional security verification by covering specific items across a wider range compared to existing methods. Based on the identified weaknesses, it detects the cause of vulnerability and monitors the related settings.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1210-1230
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• 2015

Android is the world's most utilized smartphone OS which consequently, also makes it an attractive target for attackers. The most representative method of hacking used against Android apps is known as repackaging. This attack method requires extensive knowledge about reverse engineering in order to modify and insert malicious codes into the original app. However, there exists an easier way which circumvents the limiting obstacle of the reverse engineering. We have discovered a method of exploiting the Android code-signing process in order to mount a malware as an example. We also propose a countermeasure to prevent this attack. In addition, as a proof-of-concept, we tested a malicious code based on our attack technique on a sample app and improved the java libraries related to code-signing/verification reflecting our countermeasure.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.180-187
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• 2020

Security threats are increasing with interest due to the mass spread of smart devices, and vulnerabilities in developed applications are being exposed while mobile malicious codes are spreading. The government and companies provide various applications for the public, and for reliability and security of applications, security checks are required during application development. In this paper, among the security threats that can occur in the mobile service environment, we set up the vulnerability analysis items to respond to security threats when developing Android-based applications. Based on the set analysis items, vulnerability analysis was performed by examining three applications of public institutions and private companies currently operating as mobile applications. As a result of application security checks used by three public institutions and companies, authority management and open module stability management were well managed. However, it was confirmed that many security vulnerabilities were found in input value verification, outside transmit data management, and data management. It is believed that it will contribute to improving the safety of mobile applications through the case of vulnerability analysis for Android application security.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.743-755
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• 2013

In recent years, the malicious apps with malicious code in normal apps are increasingly redistributed in Android market, which may incur various problems such as the leakage of authentication information and transaction information and fraudulent transactions when banking apps to process the financial transactions are exposed to such attacks. Thus the financial authorities established the laws and regulations as an countermeasures against those problems and domestic banks provide the integrity verification functions in their banking apps, yet its reliability has not been verified because the studies of the safety of the corresponding functions have seldom been conducted. Thus this study suggests the vulnerabilities of the integrity verification functions of banking apps by using Android reverse engineering analysis techniques. In case the suggested vulnerabilities are exploited, the integrity verification functions of banking apps are likely to be bypassed, which will facilitate malicious code inserting attacks through repackaging and its risk is very high as proved in a test of this study. Furthermore this study suggests the specific solutions to those vulnerabilities, which will contribute to improving the security level of smartphone financial transaction environment against the application forgery attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1553-1561
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• 2018

The source code for Android is open and easy to modify depending on the purpose. Recently, this charateristic has been exploited to bypass the runtime protection technique and extract the original executable code. Unfortunately, Android devices are so fragmented that it is difficult to verify the integrity of the system. To solve this problem, this paper proposes a technique to verify the integrity of the execution environment indirectly using the features of the application permission. Before executing the original executable code, it loads and executes the dummy DEX file to monitor for abnormal events and determine whether the system is intact. The proposed technique shows a performance overhead of about 2 seconds and shows that it can detect the bypassing technique that is currently disclosed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.6
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• pp.1477-1489
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• 2019

In this study, we analyzed the privacy policies of 50 Android applications that are on the top chart in EU members to present the methods for enhancing transparency based on GDPR (General Data Protection Regulation). Based on the guidelines in relation to transparency stipulated in WP29, this study extracted factors of transparency in order to ensure transparency of privacy data processing and carried out the verification procedures for each factor. The results revealed that the privacy policies provided in Google Play Store and applications need to be matched, the descriptions of the privacy policies need to be written in clear and plain language for readers to understand easily. and that it is necessary to provide information quickly and improve the descriptions of information which the data controller discloses. The research findings of this study could be used as a preliminary data for proactive responses to the EU's GDPR by substantially complying with the transparency of GDPR.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1659-1673
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• 2019

Android platform provides In-app Billing service for purchasing valuable items inside mobile applications. However, it has become a major target for attackers to achieve valuable items without actual payment. Especially, application developers suffer from automated attacks targeting all the applications in the device, not a specific application. In this paper, we propose a novel scheme detecting automated attacks with probabilistic tests. The scheme tests the signature verification method in a non-deterministic way, and if the method was replaced by the automated attack, the scheme detects it with very high probability. Both the analysis and the experiment result show that the developers can prevent their applications from automated attacks securely and efficiently by using of the proposed scheme.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.123-132
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• 2014

In this paper, we study the verification techniques for OS integrity that can be more fatal than applications in case of security issues. The dissemination of smartphones is rapidly progressing and there are many similarities of smartphones and PCs in terms of security risks. Recently, in mobile network environment, there is a trend of increasing damages and now, there are active researches on a system that can comprehensively respond to this. As a way to prevent these risks, integrity checking method on operation system is being researched. As most integrity checking algorithms are classified by verification from the levels before booting the OS and at the time of passing on the control to the OS, in which, there are minor differences in the definitions of integrity checking or its methods. In this paper, we suggests the integrity verification technique of OS using a boot loader and a physically independent storing device in the mobile device.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.669-671
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• 2012

스마트폰이 보급화 되면서 많은 사람들이 스마트폰을 사용하게 되었고 그중에서도 안드로이드는 높은 사용률로 여러 악성 어플리케이션들의 타겟이 되고 있다. 본 고에서는 앞의 문제점을 방지하기 위해 안드로이드의 보안기법을 소개하고 정상적인 마켓을 통하지 않고 인터넷 등에서 받은 보안성이 검증되지 않은 어플리케이션 등에 의한 피해를 방지하기 위한 검증 시스템을 제안한다.