Operating system kernels present a difficult security challenge. Despite
their millions of lines of code and broad, complex attack surface, they
remain a trusted component shared between all applications. If an attacker
can combine an exploit for any application on a system with a kernel
exploit or privilege escalation, the attacker can then control any other
application, regardless of whether the second application was itself
vulnerable.
This dissertation presents two hypervisor-based systems: OSck, which increases
the trustworthiness of a guest kernel by detecting kernel rootkits, and
InkTag, which removes the need for an application to trust the kernel at
all. Vital to both systems is their use of information from a potentially
malicious kernel. These systems rely on information from the kernel about
its own functionality to make their implementation simpler, more efficient,
and more secure. Importantly, although they rely on this information, they
do not trust it. A kernel that lies about its functionality to appear
benign will be detected, as will a kernel that simply acts maliciously.
OSck detects kernel rootkits: malicious software programs that are
particularly difficult to detect because they modify internal kernel
operation to hide their presence. Running concurrently with an operating
system and isolated by the hypervisor, OSck verifies safety properties for
large portions of the kernel heap with minimal overhead, by deducing type
information from unmodified kernel source code and in-memory kernel data
structures.
InkTag gives strong safety guarantees to trusted applications, even in the
presence of a malicious operating system. InkTag isolates applications
from the operating system, and enables applications to validate that the
kernel is acting in good faith, for example by ensuring that the kernel is
mapping the correct file data into the application's address space.
InkTag introduces paraverification, a technique that simplifies the
InkTag hypervisor by forcing the untrusted operating system to participate
in its own verification. InkTag requires that the kernel prove to the
hypervisor that its updates to application state (such as page tables) are
valid, and also to prove to the application that its responses to system
calls are consistent. InkTag is also the first system of its kind to
implement access control, secure naming, and consistency for data on stable
storage. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/23318 |
| Date | 25 February 2014 |
| Creators | Hofmann, Owen Sebastian |
| Source Sets | University of Texas |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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