Computer security has become a central focus in the information age. Though enormous effort has been expended on ensuring secure computation, software exploitation remains a serious threat. The software attack surface provides many avenues for hijacking; however, most exploits ultimately rely on the successful execution of a control-flow attack. This pervasive diversion of control flow is made possible by the pollution of control flow structure with attacker-injected runtime data.Many control-flow attacks persist because the root of the problem remains: runtime data is allowed to enter the program counter. In this paper, we propose a novel approach: Control-Data Isolation. Our approach provides protection by going to the root of the problem and removing all of the operations that inject runtime data into program control. While previous work relies on CFG edge checking and labeling, these techniques remain vulnerable to attacks such as heap spray, read, or GOT attacks and in some cases suffer high overheads. Rather than addressing control-flow attacks by layering additional complexity, our work takes a subtractive approach; subtracting the primary cause of contemporary control-flow attacks. We demonstrate that control-data isolation can assure the integrity of the programmer's CFG at runtime, while incurring average performance overheads of less than 7% for a wide range of benchmarks.

Arbitrary code injection pervades as a central issue in computer security where attackers seek to exploit the software attack surface. A key component in many exploits today is the successful execution of a control-flow attack. Control-Data Isolation (CDI) has emerged as a work which eliminates the root cause of contemporary control-flow attacks: indirect control flow instructions. These instructions are replaced by direct control flow edges dictated by the programmer and encoded into the application by the compiler. By subtracting the root cause of control-flow attack, ControlData Isolation sidesteps the vulnerabilities and restrictive threat models adopted by other solutions in this space (e.g., Control-Flow Integrity). The CDI approach, while eliminating contemporary control-flow attacks, introduces non-trivial overheads to validate indirect targets at runtime. In this work we introduce novel architectural support to accelerate the execution of CDIcompliant code. Through the addition of an edge cache, we are able to cache legal indirect target edges and eliminate nearly all execution overhead for indirection-free applications. We demonstrate that through memoization of compiler-confirmed control flow transitions, overheads are reduced from 19% to 0.5% on average for ControlData Isolated applications. Additionally, we show that the edge cache can efficiently provide the double-duty of predicting multi-way branch targets, thus providing even speedups for some CDI-compliant executions, compared to an architecture with unsophisticated indirect control prediction (e.g., BTB). Categories and Subject Descriptors[Security and privacy]: Domain-specific security and privacy architectures, Software security engineering Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Permissions@acm.org.

Software bugs comprise the greatest threat to computer security today. Though

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