Heejo Lee

Korea University | KU · Department of Computer Science and Engineering

Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) is a wireless technology used in billions of devices. Recently, several Bluetooth fuzzing studies have been conducted to detect vulnerabilities in Bluetooth devices, but they fall short of effectively generating malformed packets. In this paper, we propose L2FUZZ, a stateful fuzzer to detect vulnerab...

An adversary can use SSH communication as a route for information leakage or hacking. Many studies have focused on TCP header analysis to detect encrypted communication. However, SSH detection using TCP header analysis is limited when changing TCP port information or modifying components of the SSH protocol. Various machine-learning (ML) techniques...

In the machine learning-based detection model, the detection accuracy tends to be proportional to the quantity and quality of the training dataset. The machine learning-based SSH detection model’s performance is affected by the size of the training dataset and the ratio of target classes. However, in an actual network environment within a short per...

Security patches play an important role in detecting and fixing one-day vulnerabilities. However, collecting abundant security patches from diverse data sources is not a simple task. This is because (1) each data source provides vulnerability information in a different way and (2) many security patches cannot be directly collected from Common Vulne...

Cryptojacking is often used by attackers as a means of gaining profits by exploiting users’ resources without their consent, despite the anticipated positive effect of browser-based cryptomining. Previous approaches have attempted to detect cryptojacking websites, but they have the following limitations: (1) they failed to detect several cryptojack...

Z-Wave smart home devices are used to save energy, increase comfort, and remotely monitor home activities. In the past, security researchers found Z-Wave device vulnerabilities through reverse engineering, manual audits, and penetration testing. However, they did not fully use fuzzing, which is an automated cost-effective testing technique. Thus, i...

Z-Wave smart home Internet of Things devices are used to save energy, increase comfort, and remotely monitor home activities. In the past, security researchers found Z-Wave device vulnerabilities through reverse engineering, manual audits, and penetration testing. However, they did not fully use fuzzing, which is an automated cost-effective testing...

Common Vulnerabilities and Exposures (CVEs) are used to ensure confidence among developers, to share information about software vulnerabilities, and to provide a baseline for security measures. Therefore, the correctness of CVE reports is crucial for detecting and patching software vulnerabilities. In this paper, we introduce the concept of "Vulne...

Due to code reuse among software packages, vulnerabilities can propagate from one software package to another. Current code clone detection techniques are useful for preventing and managing such vulnerability propagation. When the source code for a software package is not available, such as when working with proprietary or custom software distribut...

IoT, which is closely connected with our daily life, shows high growth in the automotive, healthcare, and retail fields. IoT security threats can cause severe problems in our lives. However, the security of the IoT network is insufficient to cope with security threats. Therefore, an attacker can use man-in-the-middle-attacks (MITM), DNS manipulatio...

The current state of security and availability of the Internet is far from being commensurate with its importance. The number and strength of DDoS attacks conducted at the network layer have been steadily increasing. However, the single path (SP) routing used in today’s Internet lacks a mitigation scheme to rapidly recover from network attacks or l...

Open-source software (OSS) is widely reused as it provides convenience and efficiency in software development. Despite evident benefits, unmanaged OSS components can introduce threats, such as vulnerability propagation and license violation. Unfortunately, however, identifying reused OSS components is a challenge as the reused OSS is predominantly...

In this article, we propose a creation order reconstruction method of deleted files for the FAT32 file system with Windows operating systems. Creation order of files is established using a correlation between storage locations of the files and their directory entry locations. This method can be utilized to derive the creation-time bound of files re...

We present VeriSmart, a highly precise verifier for ensuring arithmetic safety of Ethereum smart contracts. Writing safe smart contracts without unintended behavior is critically important because smart contracts are immutable and even a single flaw can cause huge financial damage. In particular, ensuring that arithmetic operations are safe is one...

With the growth of open source software (OSS), code clones - code fragments that are copied and pasted within or between software systems - are proliferating. Although code cloning may expedite the process of software development, it often critically affects the security of software because vulnerabilities and bugs can easily be propagated through...

The proportion of packed malware has been growing rapidly and now comprises more than 80 % of all existing malware. In this paper, we propose a method for classifying the packing algorithms of given unknown packed executables, regardless of whether they are malware or benign programs. First, we scale the entropy values of a given executable and con...

Packing algorithms are broadly used to avoid anti-malware systems, and the proportion of packed malware has been growing rapidly. However, just a few studies have been conducted on detection various types of packing algorithms in a systemic way. Following this understanding, we elaborate a method to classify packing algorithms of a given executable...

Internet protocol (IP) spoofing is a serious problem on the Internet. It is an attractive technique for adversaries who wish to amplify their network attacks and retain anonymity. Many approaches have been proposed to prevent IP spoofing attacks; however, they do not address a significant deployment issue, i.e., filtering inefficiency caused by a l...

Since the introduction of BitTorrent protocol in 2001, everything can be downloaded through file sharing, including music, movies and software. As a result, the copyright holder suffers from illegal sharing of copyright content. In order to solve this problem, countries have enacted illegal share related law; and internet service providers block pi...

Finding software vulnerabilities in source code before the program gets deployed is crucial to ensure the software quality. Existing source code auditing tools for vulnerability detection generate too many false positives, and only limited types of vulnerability can be detected automatically. In this paper, we propose an extendable mechanism to rev...

Video content stored in Video Event Data Recorders (VEDRs) are used as important evidence when certain events such as vehicle collisions occur. However, with sophisticated video editing software, assailants can easily manipulate video records to their advantage without leaving visible clues. Therefore, the integrity of video content recorded throug...

We present an identity authentication system which is cryptographically strong, pseudonymous, efficient enough to run well on current smart phone devices, and easily extensible for payment and banking functionality. We also describe high security algorithm and programming methods for the implementation, including server, network transmission, and a...

With a rapid yearly growth rate, software vulnerabilities are making great threats to the system safety. In theory, detecting and removing vulnerabilities before the code gets ever deployed can greatly ensure the quality of software released. However, due to the enormous amount of code being developed as well as the lack of human resource and exper...

Domain Name System (DNS) traffic has become a rich source of information from a security perspective. However, the volume of DNS traffic has been skyrocketing, such that security analyzers experience difficulties in collecting, retrieving, and analyzing the DNS traffic in response to modern Internet threats. More precisely, much of the research rel...

DDoS attacks have been used for paralyzing popular Internet services. Especially, amplification attacks have grown dramatically in recent years. Defending against amplification attacks is challenging since the attacks usually generate extremely hugh amount of traffic and attack traffic is coming from legitimate servers, which is hard to differentia...

The articles in this special section is designed to provide a venue for state-of-the-art research being doing in how signal and information processing is advancing the field of information privacy.

Minnaard proposed a novel method that constructs a creation time bound of files recovered without time information. The method exploits a relationship between the creation order of files and their locations on a storage device managed with the Linux FAT32 file system. This creation order reconstruction method is valid only in non-wraparound situati...

The past decade has seen many proposals for future Internet architectures. Most of these proposals require substantial changes to the current networking infrastructure and end-user devices, resulting in a failure to move from theory to real-world deployment. This paper describes one possible strategy for bootstrapping the initial deployment of futu...

Software vulnerability has long been considered an important threat to the system safety. A vulnerability is often reproduced because of the frequent code reuse by programmers. Security patches are usually not propagated to all code clones; however, they could be leveraged to discover unknown vulnerabilities. Static code auditing approaches are fre...

Internet attacks often use IP spoofing to forge the source IP address of packets, and thereby hide the identity of the source. It causes many serious security problems such as the difficulty of packet authenticity and IP traceback. While many IP spoofing prevention techniques have been proposed apart from ingress filtering, none have achieved wides...

Prevalent Wi-Fi networks have adopted various protections to prevent eavesdropping caused by the intrinsic shared nature of wireless medium. However, many of them are based on pre-shared secret incurring key management costs, and are still vulnerable from practical countermeasures. In this study, we investigate the feasibility of using defensive ja...

The sharp increase in smartphone malware has become one of the most serious security problems. Since the Android platform has taken the dominant position in smartphone popularity, the number of Android malware has grown correspondingly and represents critical threat to the smartphone users. This rise in malware is primarily attributable to the occu...

For digital forensic investigations, the proposed scheme verifies the integrity of video contents in legacy surveillance camera systems with no built-in integrity protection. The scheme exploits video frames remaining in slack space of storage media, instead of timestamp information vulnerable to tampering. The scheme is applied to integrity verifi...

Software vulnerability has long been considered an important threat to the system safety. A vulnerability often gets reproduced due to the frequent code reuse by programmers. Security patches are often not propagated to all code clones, however they could be leveraged to discover unknown vulnerabilities. Static auditing approaches are frequently pr...

Mobile malware has been recently recognized as a significant problem in accordance with the rapid growth of the market share for smartphones. Despite of the numerous efforts to thwart the growth of mobile malware, the number of mobile malware is getting increased by evolving themselves. By applying, for example, code obfuscation or junk code insert...

Botnets are widely used for acquiring economic profits, by launching attacks such as distributed denial-of-service (DDoS), identification theft, ad-ware installation, mass spamming, and click frauds. Many approaches have been proposed to detect botnet, which rely on end-host installations or operate on network traffic with deep packet inspection. T...

The number of malicious applications, sometimes known as malapps, in Android smartphones has increased significantly in recent years. Malapp writers abuse repackaging techniques to rebuild applications with code changes. Existing anti-malware applications do not successfully defeat or defend against the repackaged malapps due to numerous variants....

The botnets are one of the most dangerous species of network–based attack. They cause severe network disruptions through massive coordinated attacks nowadays and the results of this disruption frequently cost enterprises large sums in financial losses. In this paper, we make an in–depth investigation on the issue of botnet detection and present a n...

Distributed denial-of-service (DDoS) attacks are one of the most difficult issues in network security and communications. This paper is a part of research project that applies distributed defense against distributed attacks. The aim of this project is to provide services by distributing load from one main server to an infrastructure of cloud-based...

Surveillance is a critical measure to break anonymity. While surveillance with unlimited resources is often assumed as a means, against which, to design stronger anonymity algorithms, this paper addresses the general impact of limited resource on surveillance efficiency. The general impact of limited resource on identifying a hidden group is experi...

This book constitutes the thoroughly refereed proceedings of the 14th International Workshop on Information Security Applications, WISA 2013, held on Jeju Island, Korea, in August 2013. The 15 revised full papers and 2 short papers presented were carefully reviewed and selected from 39 submissions. The papers are organized in topical sections such...

Distributed denial-of-service (DDoS) attacks are considered to be among the most crucial security challenges in current networks because they significantly disrupt the availability of a service by consuming extreme amount of resource and/or by creating link congestions. One type of countermeasure against DDoS attacks is a filter-based approach wher...

Packing is widely used for bypassing anti-malware systems, and the proportion of packed malware has been growing rapidly, making up over 80% of malware. Few studies on detecting packing algorithms have been conducted during last two decades. In this paper, we propose a method to classify packing algorithms of given packed executables. First, we con...

IP spoofing is attractive to amplify network attacks and to provide anonymity. Many approaches have to prevent IP spoofing attacks; however, they do not address a significant deployment issue: filtering inefficiency caused by lack of incentives for early adopters. Practically, no mechanism has been widely deployed and none successfully blocks IP sp...

Software vulnerability has long been considered an important threat to the safety of software systems. When source code is accessible, we can get much help from the information of source code to detect vulnerabilities. Static analysis has been used frequently to scan code for errors that cause security problems when source code is available. Howeve...

This document describes techniques for using features extracted from a URL to detect a malicious URL and categorize the malicious URL as one of a phishing URL, a spamming URL, a malware URL or a multi-type attack URL. The techniques employ one or more machine learning algorithms to train classification models using a set of training data which incl...

DDoS attacks continue to be a major threat to network security. Several new types of attacks such as Layer-7 attacks (e.g., HTTP flood, Slowloris, RUDY, etc.) have emerged. We propose a novel DDoS defense mechanism called DROP-FAST. Our mechanism provides distributed DDoS defense utilizing multiple replicas of the protected server throughout a clou...

The sharp increase of smartphone malwares has become one of the most serious security problems. The most significant part of the growth is the variants of existing malwares. A legacy approach for malware, the signature matching, is efficient in temporal dimension, but it is not practical because of its lack of robustness against the variants. A cou...

User activity reconstruction is a technique used in digital forensic investigation. Using this technique, digital forensic investigators extract a list of user activities from digital artifacts confiscated at the crime scene. Based on the list, explicit knowledge about the crime, such as motive, method, time, and place, can be deduced. Until now, a...

A smart grid is verging on a promising technology to reform the world’s electrical grids. Currently, attackers compromise security and privacy by maliciously modifying the memory of smart grid devices. Software-based attestation protocols establish the absence of malicious changes by the attacker. A verifier and a target device locally generate the...

Malware landscape has been dramatically elevated over the last decade. The main reason of the increase is that new malware variants can be produced easily using simple code obfuscation techniques. Once the obfuscation is applied, the malware can change their syntactics while preserving semantics, and bypass anti-virus (AV) scanners. Malware authors...

Since early responses are crucial to reduce the damage from unknown Internet attacks, our first consideration while developing a defense mechanism can be on time efficiency and observing (and predicting) the change of network statuses, even at the sacrifice of accuracy. In the recent security field, it is an earnest desire that a new mechanism to p...

The Internet plays an increasing role in content dissemination as user-generated contents have exploded recently. Cache servers have been deployed to bypass bottlenecks in the network so that contents can be delivered to end users more efficiently. With caches becoming more embedded in the networks, emerging threats follow naturally. A cache pollut...

With rampant deployment of wireless technologies such as WLAN, information leakage is increasingly becoming a threat for its serious adopters such as enterprises. Research on antidotes has been mainly focused on logical measures such as authentication protocols and secure channels, but an inside collaborator can readily circumvent such defenses and...

Wireless access points (APs) are widely used for the convenience and productivity of smartphone users. The growing popularity of wireless local area networks (WLANs) increases the risk of wireless security attacks. A fake AP can be set in any public space in order to impersonate legitimate APs for monetization. Existing fake AP detection methods an...

It is often appealing to assume that existing solutions can be directly applied to emerging engineering domains. Unfortunately, careful investigation of the unique challenges presented by new domains exposes its idiosyncrasies, thus often requiring new approaches and solutions. In this paper, we argue that the “smart” grid, replacing its incredibly...

Botnets have become the main vehicle to conduct online crimes such as DDoS, spam, phishing and identity theft. Even though numerous efforts have been directed towards detection of botnets, evolving evasion techniques easily thwart detection. Moreover, existing approaches can be overwhelmed by the large amount of data needed to be analyzed. In this...

The proposed scheduling scheme minimizes the energy consumption of a real-time task on the multi-core processor with the dynamic voltage and frequency scaling capability. The scheme allocates a pertinent number of cores to the task execution, inactivates unused cores, and assigns the lowest frequency meeting the deadline. For a periodic real-time t...

Distributed denial-of-service (DDoS) attacks continue to pose an important challenge to current networks. DDoS attacks can cause victim resource consumption and link congestion. A filter-based DDoS defense is considered as an effective approach, since it can defend against both attacks: victim resource consumption and link congestion. However, exis...

Malicious URLs have been widely used to mount various cyber attacks including spamming, phishing and malware. Detection of malicious URLs and identification of threat types are critical to thwart these attacks. Knowing the type of a threat enables estimation of severity of the attack and helps adopt an effective countermeasure. Existing methods typ...

Defeating botnet is the key to secure Internet. A lot of cyber attacks are launched by botnets including DDoS, spamming, click frauds and information thefts. Despite of numerous methods have been proposed to detect botnets, botnet detection is still a challenging issue, as adversaries are constantly improving bots to write them stealthier. Existing...

As a smart grid is becoming a promising technology to control and save power generation and consumption, smart grid security should be a preliminary consideration to prevent from catastrophic failures. Especially, excessive power consumption can be a significant issue, because power provider cannot react quickly to such massive demand that can caus...

A smart meter is one of the key elements of smart girds. An attacker can compromise smart meters by injecting malicious codes, and take financial benefits by modifying memory contents of the smart meters. An attestation scheme can prevent such a memory forgery attack as verifying memory contents. In smart grids, however, attestation processes are r...

In the recent years, malicious codes called malware are having shown significant increase due to the code obfuscation to evade detection mechanisms. When the code obfuscation technique is applied to malwares, they can change their instruction sequence and also even their signature. These malwares which have same functionality and different appearan...

Malwares attempt to evade AV scanners using various obfuscation techniques. Packing is a popular obfuscation technique used by 80% of malwares. In this paper, we propose a generic unpacking mechanism to find the original entry point (OEP) using entropy analysis. The experiment using 110 packed executables demonstrates the proposed mechanism can loc...

Botnets have been considered as a main source of Internet threats. A common feature of recent botnets is the use of one or more C&C servers with multiple domain names for the purpose of increasing flexibility and survivability. In contrast with single domain botnets, these multi domain botnets are hard to be quarantined because they change domain n...

Cloud computing is now regarded as one of social phenomenon that satisfy customers’ needs. It is possible that the customers’ needs and the primary principle of economy – gain maximum benefits from minimum investment – reflects realization of cloud computing. We are living in the connected society with flood of information and without connected com...

The continuous growth of attacks in the Internet causes to generate a number of rules in security devices such as Intrusion Prevention Systems, firewalls, etc. Policy anomalies in security devices create security holes and prevent the system from determining quickly whether allow or deny a packet. Policy anomalies exist among the rules in multiple...

In hospital information systems, protecting the confidentiality of health information, whilst at the same time allowing authorized physicians to access it conveniently, is a crucial requirement. The need to deliver health information at the point-of-care is a primary factor to increase healthcare quality and cost efficiency. However, current system...

Policy in security devices such as firewalls and Network Intrusion Prevention Systems (NIPS) is usually implemented as a sequence of rules. This allows network packets to proceed or to be discarded based on rule's decision. Since attack methods are increasing rapidly, a huge number of security rules are generated and maintained in security devices....

Wireless body area networks (WBAN) consist of resource constrained sensing devices just like other wireless sensor networks (WSN). However, they differ from WSN in topology, scale and security requirements. Due to these differences, key management schemes designed for WSN are inefficient and unnecessarily complex when applied to WBAN. Considering t...

Full network level privacy has often been categorized into four sub-categories: Identity, Route, Location and Data privacy. Achieving full network level privacy is a critical and challenging problem due to the constraints imposed by the sensor nodes (e.g., energy, memory and computation power), sensor networks (e.g., mobility and topology) and QoS...

Until recently, researchers have focused on the cry ptographic-based security issues more intensively t han the privacy and trust issues. However, without the incorporation of trust and privacy features, cryptographic-based security mechanisms are not capable of singlehandedly providing robustness, reliability and completeness in a security solutio...

Wireless sensor networks (WSN) are susceptible to node capture and many network levels attacks. In order to provide protection against such threats, WSNs require lightweight and scalable key management schemes because the nodes are resource-constrained and high in number. Also, the effect of node compromise should be minimized and node capture shou...

Network resiliency has become crucial as the failure of a group of networks happens more frequently, being caused by either natural disasters or malicious attacks. In order to enhance the resiliency of the Internet, we show that changing the evolving strategy is more important than increasing the number of links by multihoming, which connects a sin...

Malware writers and detectors have been running an endless battle. Self-defense is the weapon most malware writers prepare against malware detectors. Malware writers have tried to evade the improved detection techniques of anti-virus(AV) products. Packing and code obfuscation are two popular evasion techniques. When these techniques are applied to...

Full network level privacy has often been categorized into four sub-categories: Identity, Route, Location and Data privacy. Achieving full network level privacy is a critical and challenging problem due to the constraints imposed by the sensor nodes (e.g., energy, memory and computation power), sensor networks (e.g., mobility and topology) and QoS...

For many mission-critical related wireless sensor net-work applications such as military and homeland security, user's access restriction is necessary to be enforced by access control mechanisms for different access rights. Public key-based access control schemes are more attractive than symmetric-key based approaches due to high scalability, low m...

Wireless technologies have had a significant impact on computing and communication technologies in the past decade, and we are thus now progressing to the new "anytime-anywhere" service model of the mobile Internet. Unfortunately, the affordability and availability of wireless technologies that makes them so attractive, also makes them an enticing...

Traditional trust management schemes developed for wired and wireless ad hoc networks are not well suited for sensor networks due to their higher consumption of resources such as memory and power. In this work, we propose a new lightweight group-based trust management scheme (GTMS) for wireless sensor networks, which employs clustering. Our approac...

We propose a novel scheduling scheme that determines the instant operation modes of multiple tasks. The tasks have probabilistic execution times and are executed on discrete operation modes providing different utilities with different energy consumptions. We first design an optimal offline scheduling scheme that stochastically maximizes the cumulat...

Network intrusion detection systems rely on a signature-based detection engine. When under attack or during heavy traffic, the detection engines need to make a fast decision whether a packet or a sequence of packets is normal or malicious. However, if packets have a heavy payload or the system has a great deal of attack patterns, the high cost of p...

This article introduces a novel anomaly detection method that makes use of only matrix operations and is highly sensitive to randomness in traffic. The sensitivity can be leveraged to detect attacks that exude randomness in traffic characteristics, such as denial-of-service attacks and worms. In particular, we show that the method can be used to al...