Biblio

OS kernel is the core part of the operating system, and it plays an important role for OS resource management. A popular way to compromise OS kernel is through a kernel rootkit (i.e., malicious kernel module). Once a rootkit is loaded into the kernel space, it can carry out arbitrary malicious operations with high privilege. To defeat kernel rootkits, many approaches have been proposed in the past few years. However, existing methods suffer from some limitations: 1) most methods focus on user-mode rootkit detection; 2) some methods are limited to detect obfuscated kernel modules; and 3) some methods introduce significant performance overhead. To address these problems, we propose VKRD, a kernel rootkit detection system based on the hardware assisted virtualization technology. Compared with previous methods, VKRD can provide a transparent and an efficient execution environment for the target kernel module to reveal its run-time behavior. To select the important run-time features for training our detection models, we utilize the TF-IDF method. By combining the hardware assisted virtualization and machine learning techniques, our kernel rootkit detection solution could be potentially applied in the cloud environment. The experiments show that our system can detect windows kernel rootkits with high accuracy and moderate performance cost.

Cryptography is widely adopted in computer systems to protect the confidentiality of sensitive information. The security relies on the assumption that cryptography keys are never leaked, which may be broken by the memory disclosure attacks, e.g., the Heartbleed and coldboot attacks. Various schemes are proposed to defend against memory disclosure attacks, e.g., performing the cryptographic computations in registers, or adopting the hardware features (e.g., Intel TSX and Intel SGX) to ensure that the plaintext of the cryptography key never appears in memory. However, these schemes are still not widely deployed due to the following limitations: (a) Most of the schemes are deployed in the OS kernel and require the root (or administrator) privileges of the host; and (b) They require the programmers to integrate these protection schemes in the implementation of different cryptography algorithms on different platforms. In this paper, we propose a tool implemented in Clang/LLVM, named Peapods, which provides the user-mode protection for cryptographic keys in software engines. It introduces one qualifier and three intrinsics for the programmers to specify the sensitive variables and code fragments to be protected, making it easier to be deployed. Peapods adopts transactional memory to protect cryptographic keys, while it is OS-independent and does not require the cryptographic computation performed in the OS kernel. Peapods supports the automatic protection between transactions for better performance. We have implemented the prototype of Peapods. Evaluation results demonstrate that Peapods achieves the design goals with a modest overhead (less than 10%).

An important principle in computational security is to reduce the attack surface, by maintaining the Trusted Computing Base (TCB) small. Even so, no security technique ensures full protection against any adversary. Thus, sensitive applications should be designed with several layers of protection so that, even if a layer might be violated, sensitive content will not be compromised. In 2015, Intel released the Software Guard Extensions (SGX) technology in its processors. This mechanism allows applications to allocate enclaves, which are private memory regions that can hold code and data. Other applications and even privileged code, like the OS kernel and the BIOS, are not able to access enclaves' contents. This paper presents a novel password file protection scheme, which uses Intel SGX to protect authentication credentials in the PAM authentication framework, commonly used in UNIX systems. We defined and implemented an SGX-enabled version of the pam\_unix.so authentication module, called UniSGX. This module uses an SGX enclave to handle the credentials informed by the user and to check them against the password file. To add an extra security layer, the password file is stored using SGX sealing. A threat model was proposed to assess the security of the proposed solution. The obtained results show that the proposed solution is secure against the threat model considered, and that its performance overhead is acceptable from the user point of view. The scheme presented here is also suitable to other authentication frameworks.

Smartphones are a new type of mobile devices that users can install additional mobile software easily. In the almost all smartphone applications, client-server model is used because end-to-end communication is prevented by NAT routers. Recently, some smartphone applications provide real time services such as voice and video communication, online games etc. In these applications, end-to-end communication is suitable to reduce transmission delay and achieve efficient network usage. Also, IP mobility and security are important matters. However, the conventional IP mobility mechanisms are not suitable for these applications because most mechanisms are assumed to be installed in OS kernel. We have developed a novel IP mobility mechanism called NTMobile (Network Traversal with Mobility). NTMobile supports end-to-end IP mobility in IPv4 and IPv6 networks, however, it is assumed to be installed in Linux kernel as with other technologies. In this paper, we propose a new type of end-to-end mobility platform that provides end-to-end communication, mobility, and also secure data exchange functions in the application layer for smartphone applications. In the platform, we use NTMobile, which is ported as the application program. Then, we extend NTMobile to be suitable for smartphone devices and to provide secure data exchange. Client applications can achieve secure end-to-end communication and secure data exchange by sharing an encryption key between clients. Users also enjoy IP mobility which is the main function of NTMobile in each application. Finally, we confirmed that the developed module can work on Android system and iOS system.
 

Smartphones are a new type of mobile devices that users can install additional mobile software easily. In the almost all smartphone applications, client-server model is used because end-to-end communication is prevented by NAT routers. Recently, some smartphone applications provide real time services such as voice and video communication, online games etc. In these applications, end-to-end communication is suitable to reduce transmission delay and achieve efficient network usage. Also, IP mobility and security are important matters. However, the conventional IP mobility mechanisms are not suitable for these applications because most mechanisms are assumed to be installed in OS kernel. We have developed a novel IP mobility mechanism called NTMobile (Network Traversal with Mobility). NTMobile supports end-to-end IP mobility in IPv4 and IPv6 networks, however, it is assumed to be installed in Linux kernel as with other technologies. In this paper, we propose a new type of end-to-end mobility platform that provides end-to-end communication, mobility, and also secure data exchange functions in the application layer for smartphone applications. In the platform, we use NTMobile, which is ported as the application program. Then, we extend NTMobile to be suitable for smartphone devices and to provide secure data exchange. Client applications can achieve secure end-to-end communication and secure data exchange by sharing an encryption key between clients. Users also enjoy IP mobility which is the main function of NTMobile in each application. Finally, we confirmed that the developed module can work on Android system and iOS system.