As the web continues to play an ever increasing role in information exchange, so too is it becoming the prevailing platform for infecting vulnerable hosts. In this paper, we provide a detailed study of the pervasiveness of so-called drive-by downloads on the Internet. Drive-by downloads are caused by URLs that attempt to exploit their visitors and cause malware to be installed and run automatically. Our analysis of billions of URLs over a 10 month period shows that a non-trivial amount, of over 3 million maliciousURLs, initiate drive-by downloads. An even more troubling finding is that approximately 1.3 % of the incoming search queries to Google’s search engine returned at least one URL labeled as malicious in the results page. We also explore several aspects of the drive-by downloads problem. We study the relationship between the user browsing habits and exposure to malware, the different techniques used to lure the user into the malware distribution networks, and the different properties of these networks.

Protocol reverse engineering, the process of extracting the application-level protocol used by an implementation, without access to the protocol specification, is important for many network security applications. Recent work [17] has proposed protocol reverse engineering by using clustering on network traces. That kind of approach is limited by the lack of semantic information on network traces. In this paper we propose a new approach using program binaries. Our approach, shadowing, uses dynamic analysis and is based on a unique intuition—the way that an implementation of the protocol processes the received application data reveals a wealth of information about the protocol message format. We have implemented our approach in a system called Polyglot and evaluated it extensively using real-world implementations of five different protocols: DNS, HTTP, IRC, Samba and ICQ. We compare our results with the manually crafted message format, included in Wireshark, one of the state-ofthe-art protocol analyzers. The differences we find are small and usually due to different implementations handling fields in different ways. Finding such differences between implementations is an added benefit, as they are important for problems such as fingerprint generation, fuzzing, and error detection.

Malware has become the centerpiece of most security threats on the Internet. Malware analysis is an essential technology that extracts the runtime behavior of malware, and supplies signatures to detection systems and provides evidence for recovery and cleanup. The focal point in the malware analysis battle is how to detect versus how to hide a malware analyzer from malware during runtime. State-of-the-art analyzers reside in or emulate part of the guest operating system and its underlying hardware, making them easy to detect and evade. In this paper, we propose a transparent and external approach to malware analysis, which is motivated by the intuition that for a malware analyzer to be transparent, it must not induce any side-effects that are unconditionally detectable by malware. Our analyzer, Ether, is based on a novel application of hardware virtualization extensions such as Intel VT, and resides completely outside of the target OS environment. Thus, there are no in-guest software components vulnerable to detection, and there are no shortcomings that arise from incomplete or inaccurate system emulation. Our experiments are based on our study of obfuscation techniques used to create 25,000 recent malware samples. The results show that Ether remains transparent and defeats the obfuscation tools that evade existing approaches.

Protocol reverse engineering has often been a manual process that is considered time-consuming, tedious and error-prone. To address this limitation, a number of solutions have recently been proposed to allow for automatic protocol reverse engineering. Unfortunately, they are either limited in extracting protocol fields due to lack of program semantics in network traces or primitive in only revealing the flat structure of protocol format. In this paper, we present a system called AutoFormat that aims at not only extracting protocol fields with high accuracy, but also revealing the inherently “non-flat”, hierarchical structures of protocol messages. AutoFormat is based on the key insight that different protocol fields in the same message are typically handled in different execution contexts (e.g., the runtime call stack). As such, by monitoring the program execution, we can collect the execution context information for every message byte (annotated with its offset in the entire message) and cluster them to derive the protocol format. We have evaluated our system with more than 30 protocol messages from seven protocols, including two text-based protocols (HTTP and SIP), three binary-based protocols (DHCP, RIP, and OSPF), one hybrid protocol (CIFS/SMB), as well as one unknown protocol used by a real-world malware. Our results show that AutoFormat can not only identify individual message fields automatically and with high accuracy (an average 93.4 % match ratio compared with Wireshark), but also unveil the structure of the protocol format by revealing possible relations (e.g., sequential, parallel, and hierarchical) among the message fields.

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Abstract. In this paper, we give an overview of the BitBlaze project, a new approach to computer security via binary analysis. In particular, BitBlaze focuses on building a unified binary analysis platform and using it to provide novel solutions to a broad spectrum of different security problems. The binary analysis platform is designed to enable accurate analysis, provide an extensible architecture, and combines static and dynamic analysis as well as program verification techniques to satisfy the common needs of security applications. By extracting security-related properties from binary programs directly, BitBlaze enables a principled, root-cause based approach to computer security, offering novel and effective solutions, as demonstrated with over a dozen different security applications.

Kernel rootkits have posed serious security threats due to their stealthy manner. To hide their presence and activities, many rootkits hijack control flows by modifying control data or hooks in the kernel space. A critical step towards eliminating rootkits is to protect such hooks from being hijacked. However, it remains a challenge because there exist a large number of widely-scattered kernel hooks and many of them could be dynamically allocated from kernel heap and co-located together with other kernel data. In addition, there is a lack of flexible commodity hardware support, leading to the socalled protection granularity gap – kernel hook protection requires byte-level granularity but commodity hardware only provides pagelevel protection. To address the above challenges, in this paper, we present Hook-Safe, a hypervisor-based lightweight system that can protect thousands of kernel hooks in a guest OS from being hijacked. One key observation behind our approach is that a kernel hook, once initialized, may be frequently “read”-accessed, but rarely “write”accessed. As such, we can relocate those kernel hooks to a dedicated page-aligned memory space and then regulate accesses to them with hardware-based page-level protection. We have developed a prototype of HookSafe and used it to protect more than 5, 900 kernel hooks in a Linux guest. Our experiments with nine real-world rootkits show that HookSafe can effectively defeat their attempts to hijack kernel hooks. We also show that HookSafe achieves such a large-scale protection with a small overhead (e.g., around 6 % slowdown in performance benchmarks).

Abstract. Malicious software in form of Internet worms, computer viruses, and Trojan horses poses a major threat to the security of networked systems. The diversity and amount of its variants severely undermine the e ectiveness of classical signature-based detection. Yet variants of malware families share typical behavioral patterns reflecting its origin and purpose. We aim to exploit these shared patterns for classification of malware and propose a method for learning and discrimination of malware behavior. Our method proceeds in three stages: (a) behavior of collected malware is monitored in a sandbox environment, (b) based on a corpus of malware labeled by an anti-virus scanner a malware behavior classifier is trained using learning techniques and (c) discriminative features of the behavior models are ranked for explanation of classification decisions. Experiments with di erent heterogeneous test data collected over several months using honeypots demonstrate the e ectiveness of our method, especially in detecting novel instances of malware families previously not recognized by commercial anti-virus software. 1

This paper evaluates pointer tainting, an incarnation of Dynamic Information Flow Tracking (DIFT), which has recently become an important technique in system security. Pointer tainting has been used for two main purposes: detection of privacy-breaching malware (e.g., trojan keyloggers obtaining the characters typed by a user), and detection of memory corruption attacks against non-control data (e.g., a buffer overflow that modifies a user’s privilege level). In both of these cases the attacker does not modify control data such as stored branch targets, so the control flow of the target program does not change. Phrased differently, in terms of instructions executed, the program behaves ‘normally’. As a result, these attacks are exceedingly difficult to detect. Pointer tainting is considered one of the only methods for detecting them in unmodified binaries. Unfortunately, almost all of the incarnations of pointer tainting are flawed. In particular, we demonstrate that the application of pointer tainting to the detection of keyloggers and other privacybreaching malware is problematic. We also discuss whether pointer tainting is able to reliably detect memory corruption attacks against non-control data. We found that pointer tainting generates itself the conditions for false positives. We analyse the problems in detail and investigate various ways to improve the technique. Most have serious drawbacks in that they are either impractical (and incur many false positives still), and/or cripple the technique’s ability to detect attacks. In conclusion, we argue that depending on architecture and operating system, pointer tainting may have some

Anti-malware companies receive thousands of malware samples every day. To process this large quantity, a number of automated analysis tools were developed. These tools execute a malicious program in a controlled environment and produce reports that summarize the program’s actions. Of course, the problem of analyzing the reports still remains. Recently, researchers have started to explore automated clustering techniques that help to identify samples that exhibit similar behavior. This allows an analyst to discard reports of samples that have been seen before, while focusing on novel, interesting threats. Unfortunately, previous techniques do not scale well and frequently fail to generalize the observed activity well enough to recognize related malware. In this paper, we propose a scalable clustering approach to identify and group malware samples that exhibit similar behavior. For this, we first perform dynamic analysis to obtain the execution traces of malware programs. These execution traces are then generalized into behavioral profiles, which characterize the activity of a program in more abstract terms. The profiles serve as input to an efficient clustering algorithm that allows us to handle sample sets that are an order of magnitude larger than previous approaches. We have applied our system to real-world malware collections. The results demonstrate that our technique is able to recognize and group malware programs that behave similarly, achieving a better precision than previous approaches. To underline the scalability of the system, we clustered a set of more than 75 thousand samples in less than three hours. 1