Black-box web application vulnerability scanners attempt to automatically identify vulnerabilities in web applications without access to the source code. However, they do so by using a manually curated list of vulnerability-inducing inputs, which significantly reduces the ability of a black-box scanner to explore the web application’s input space and which can cause false negatives. In addition, black-box scanners must attempt to infer that a vulnerability was triggered, which causes false positives.To overcome these limitations, we propose Witcher, a novel web vulnerability discovery framework that is inspired by grey-box coverage-guided fuzzing. Witcher implements the concept of fault escalation to detect both SQL and command injection vulnerabilities. Additionally, Witcher captures coverage information and creates output-derived input guidance to focus the input generation and, therefore, to increase the state-space exploration of the web application. On a dataset of 18 web applications written in PHP, Python, Node.js, Java, Ruby, and C, 13 of which had known vulnerabilities, Witcher was able to find 23 of the 36 known vulnerabilities (64%), and additionally found 67 previously unknown vulnerabilities, 4 of which received CVE numbers. In our experiments, Witcher outperformed state of the art scanners both in terms of number of vulnerabilities found, but also in terms of coverage of web applications.

Dynamic memory allocators are critical components of modern systems, and developers strive to find a balance between their performance and their security. Unfortunately, vulnerable allocators are routinely abused as building blocks in complex exploitation chains. Most of the research regarding memory allocators focuses on popular and standardized heap libraries, generally used by high-end devices such as desktop systems and servers. However, dynamic memory allocators are also extensively used in embedded systems but they have not received much scrutiny from the security community.In embedded systems, a raw firmware image is often the only available piece of information, and finding heap vulnerabilities is a manual and tedious process. First of all, recognizing a memory allocator library among thousands of stripped firmware functions can quickly become a daunting task. Moreover, emulating firmware functions to test for heap vulnerabilities comes with its own set of challenges, related, but not limited, to the re-hosting problem.To fill this gap, in this paper we present HEAPSTER, a system that automatically identifies the heap library used by a monolithic firmware image, and tests its security with symbolic execution and bounded model checking. We evaluate HEAPSTER on a dataset of 20 synthetic monolithic firmware images — used as ground truth for our analyses — and also on a dataset of 799 monolithic firmware images collected in the wild and used in real-world devices. Across these datasets, our tool identified 11 different heap management library (HML) families containing a total of 48 different variations. The security testing performed by HEAPSTER found that all the identified variants are vulnerable to at least one critical heap vulnerability. The results presented in this paper show a clear pattern of poor security standards, and raise some concerns over the security of dynamic memory allocators employed by IoT devices.

Malicious software (malware) poses a significant threat to the security of our networks and users. In the ever-evolving malware landscape, Excel 4.0 Office macros (XL4) have recently become an important attack vector. These macros are often hidden within apparently legitimate documents and under several layers of obfuscation. As such, they are difficult to analyze using static analysis techniques. Moreover, the analysis in a dynamic analysis environment (a sandbox) is challenging because the macros execute correctly only under specific environmental conditions that are not always easy to create. This paper presents SYMBEXCEL, a novel solution that leverages symbolic execution to deobfuscate and analyze Excel 4.0 macros automatically. Our approach proceeds in three stages: (1) The malicious document is parsed and loaded in memory; (2) Our symbolic execution engine executes the XL4 formulas; and (3) Our Engine concretizes any symbolic values encountered during the symbolic exploration, therefore evaluating the execution of each macro under a broad range of (meaningful) environment configurations. SYMBEXCEL significantly outperforms existing deobfuscation tools, allowing us to reliably extract Indicators of Compromise (IoCs) and other critical forensics information. Our experiments demonstrate the effectiveness of our approach, especially in deobfuscating novel malicious documents that make heavy use of environment variables and are often not identified by commercial anti-virus software.

Despite a considerable number of approaches that have been proposed to protect computer systems, cyber-criminal activities are on the rise and forensic analysis of compromised machines and seized devices is becoming essential in computer security. This article focuses on memory forensics, a branch of digital forensics that extract artifacts from the volatile memory. In particular, this article looks at a key ingredient required by memory forensics frameworks: a precise model of the OS kernel under analysis, also known as profile . By using the information stored in the profile, memory forensics tools are able to bridge the semantic gap and interpret raw bytes to extract evidences from a memory dump. A big problem with profile-based solutions is that custom profiles must be created for each and every system under analysis. This is especially problematic for Linux systems, because profiles are not generic : they are strictly tied to a specific kernel version and to the configuration used to build the kernel. Failing to create a valid profile means that an analyst cannot unleash the true power of memory forensics and is limited to primitive carving strategies. For this reason, in this article we present a novel approach that combines source code and binary analysis techniques to automatically generate a profile from a memory dump, without relying on any non-public information. Our experiments show that this is a viable solution and that profiles reconstructed by our framework can be used to run many plugins, which are essential for a successful forensics investigation.

Kickstarted by the Digital Forensic Research Workshop (DFRWS) conference in 2005, modern memory analysis is now one of most active areas of computer forensics and it mostly focuses on techniques to locate key operating system data structures and extract high-level information. These techniques work on the assumption that the information inside a memory dump is consistent and the copy of the physical memory was obtained in an atomic operation. Unfortunately, this is seldom the case in real investigations, where software acquisition tools record information while the rest of the system is running. Thus, since the content of the memory is changing very rapidly, the resulting memory dump may contain inconsistent data. While this problem is known, its consequences are unclear and often overlooked. Unfortunately, errors can be very subtle and can affect the results of an analysis in ways that are difficult to detect. In this article, we argue that memory forensics should also consider the time in which each piece of data was acquired. This new temporal dimension provides a preliminary way to assess the reliability of a given result and opens the door to new research directions that can minimize the effect of the acquisition time or detect inconsistencies. To support our hypothesis, we conducted several experiments to show that inconsistencies are very frequent and can negatively impact an analysis. We then discuss modifications we made to popular memory forensic tools to make the temporal dimension explicit during the analysis and to minimize its effect by resorting to a locality-based acquisition.

Fuzzy hashing algorithms provide a convenient way of summarizing in a compact form the content of files, and of looking for similarities between them. Because of this, they are widely used in the security and forensics communities to look for similarities between binary program files; one version of them, ssdeep, is the de facto standard to share information about known malware.

Spam has been largely studied in the past years from different perspectives but, unfortunately, it is still an open problem and a lucrative and active business for criminals and bot herders. While several countermeasures have been proposed and deployed in the past decade, their impact and effectiveness is not always clear. In particular, on top of the most common content-and sender-based anti-spam techniques, two minor approaches are popular among system administrators to cope with this annoying problem: greylisting and nolisting. These techniques exploit known features of the Simple Mail Transfer Protocol (SMTP) protocol that are not often respected by spambots. This assumption makes these two countermeasures really simple to adopt and, at least in theory, quite effective. In this paper we present the first comprehensive study of nolisting and greylisting, in which we analyze these spam countermeasures from different perspectives. First, we measure their world-wide deployment and provide insights from their distribution. Second, we measure their effectiveness against areal dataset of malware samples responsible to generate over 70% of the global spam traffic. Finally, we measure the impact of these two defensive mechanisms on the delivery of normal emails. Our study provides a unique and valuable perspective on two of the most innovative and atypical anti-spam systems. Our findings may guide system administrators and security experts to better assess their anti-spam infrastructure and shed some light on myths about greylisting and nolisting.

The acquisition of volatile memory of running systems has become a prominent and essential procedure in digital forensic analysis and incident responses. In fact, unencrypted passwords, cryptographic material, text fragments and latest-generation malware may easily be protected as encrypted blobs on persistent storage, while living seamlessly in the volatile memory of a running system. Likewise, systems' run-time information, such as open network connections, open files and running processes, are by definition live entities that can only be observed by examining the volatile memory of a running system. In this context, tampering of volatile data while an acquisition is in progress or during transfer to an external trusted entity is an ongoing issue as it may irremediably invalidate the collected evidence.