In today's digital age, computer systems are prime targets for adversaries due to the vast amounts of sensitive information stored digitally. This ongoing cat-and-mouse game between programmers and adversaries forces security researchers to continually develop novel security measures. Widely adopted schemes like NX bits have safeguarded systems against traditional memory exploits such as buffer overflows, but new threats like code-reuse attacks quickly bypass these defenses. Code-reuse attacks exploit existing code sequences, known as gadgets, without injecting new malicious code, making them challenging to counter. Additionally, input-based vulnerabilities pose significant risks by exploiting external inputs to trigger malicious paths. Languages like C and C++ are often considered unsafe due to their tendency to cause issues like buffer overflows and use-after-free errors. Addressing these complex vulnerabilities requires extensive research and a holistic approach.
This dissertation initially introduces a methodology for verifying the functional equivalence between an original binary and its diversified version. The Verification of Diversified Binary (VDB) algorithm is employed to determine whether the two binaries—the original and the diversified—maintain functional equivalence. Code diversification techniques modify the binary compilation process to produce functionally equivalent yet different binaries from the same source code. Most code diversification techniques focus on analyzing non-functional properties, such as whether the technique improves security. The objective of this contribution is to enable the use of untrusted diversification techniques in essential applications. Our evaluation demonstrates that the VDB algorithm can verify the functional equivalence of 85,315 functions within binaries from the GNU Coreutils 8.31 benchmark suite.
Next, this dissertation proposes a binary-level tool that modifies binaries to protect against control-flow hijacking attacks. Traditional approaches to guard against ROP attacks either introduce significant overhead, require hardware support, or need intimate knowledge of the binary, such as source code. In contrast, this contribution does not rely on source code nor the latest hardware technology (e.g., Intel Control-flow Enforcement Technology). Instead, we show that we can precisely restrict control flow transfers from transferring to non-intended paths even without these features. To that end, this contribution proposes a novel control-flow integrity policy based on a deny list called Control-flow Restriction (CFR). CFR determines which control flow transfers are allowed in the binary without requiring source code. Our implementation and evaluation of CFR show that it achieves this goal with an average runtime performance overhead for commercial off-the-shelf (COTS) binaries in the range of 5.5% to 14.3%. In contrast, a state-of-the-art binary-level solution such as BinCFI has an average overhead of 61.5%.
Additionally, this dissertation explores leveraging the latest hardware security primitives to compartmentalize sensitive data. Specifically, we use a tagged memory architecture introduced by ARM called the Memory Tagging Extension (MTE), which assigns a metadata tag to a memory location that is associated with pointers referencing that memory location. Although promising, ARM MTE suffers from predictable tag allocation on stack data, vulnerable plain-text metadata tags, and lack of fine-grained memory access control. Therefore, this contribution introduces Shroud to enhance data security through compartmentalization using MTE and protect MTE's tagged pointers' vulnerability through encryption. Evaluation of Shroud demonstrates its security effectiveness against non-control-data attacks like Heartbleed and Data-Oriented Programming, with performance evaluations showing an average overhead of 4.2% on lighttpd and 2% on UnixBench. Finally, the NPB benchmark measured Shroud's overhead, showing an average runtime overhead of 2.57%.
The vulnerabilities highlighted by exploits like Heartbleed capitalize on external inputs, underscoring the need for enhanced input-driven security measures. Therefore, this dissertation describes a method to improve upon the limitations of traditional compartmentalization techniques. This contribution introduces an Input-Based Compartmentalization System (IBCS), a comprehensive toolchain that utilizes user input to identify data for memory protection automatically. Based on user inputs, IBCS employs hybrid taint analysis to generate sensitive code paths and further analyze each tainted data using novel assembly analyses to identify and enforce selective targets. Evaluations of IBCS demonstrate its security effectiveness through adversarial analysis and report an average overhead of 3% on Nginx.
Finally, this dissertation concludes by revisiting the problem of implementing a classical technique known as Software Fault Isolation (SFI) on an x86-64 architecture. Prior works attempting to implement SFI on an x86-64 architecture have suffered from supporting a limited number of sandboxes, high context-switch overhead, and requiring extensive modifications to the toolchain, jeopardizing maintainability and introducing compatibility issues due to the need for specific hardware. This dissertation describes x86-based Fault Isolation (XFI), an efficient SFI scheme implemented on an x86-64 architecture with minimal modifications needed to the toolchain, while reducing complexity in enforcing SFI policies with low performance (22.48% average) and binary size overheads (2.65% average). XFI initializes the sandbox environment for the rewritten binary and, depending on the instructions, enforces data-access and control-flow policies to ensure safe execution. XFI provides the security benefits of a classical SFI scheme and offers additional protection against several classes of side-channel attacks, which can be further extended to enhance its protection capabilities. / Doctor of Philosophy / In today's digital age, cyber attackers frequently target computer systems due to the vast amounts of sensitive information they store. As a result, security researchers must constantly develop new protective measures. Traditional defenses like NX bits have been effective against memory exploits, but new threats like code-reuse attacks, which leverage existing code without introducing new malicious code, present new challenges. Additionally, vulnerabilities in languages like C and C++ further complicate security efforts. Addressing these issues requires extensive research and a comprehensive approach.
This dissertation introduces several innovative techniques to enhance computer security. First, it presents a method to verify that a diversified program is functionally equivalent to its original version, ensuring that security modifications do not alter its intended functions. Next, it proposes a technique to prevent control-flow hijacking attacks without requiring source code or advanced hardware. Then, the dissertation explores leveraging advanced hardware, such as ARM's Memory Tagging Extension, to protect sensitive data, demonstrating robust security against attacks like Heartbleed. Recognizing that adversaries often use external inputs to exploit vulnerabilities, this dissertation introduces Input-Based Compartmentalization to automatically protect memory based on user input. Finally, an efficient implementation of a well-known security technique called Software Fault Isolation on x86-64 architecture ensures safe execution with low overhead. These advancements collectively enhance the robustness of computer systems against modern cyber threats.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/120718 |
| Date | 26 July 2024 |
| Creators | Jang, Jae-Won |
| Contributors | Electrical and Computer Engineering, Ravindran, Binoy, Gerdes, Ryan M., Cho, Jin-Hee, Verbeek, Freek, Wang, Haining |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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