Stack Redundancy to Thwart Return Oriented Programming in Embedded Systems

Abstract

With the emergence of Internet of Things, embedded devices are increasingly the target of software attacks. The aim of these attacks is to maliciously modify the behavior of the software being executed by the device. The work presented in this letter has been developed for the Cyber Security Awareness Week Embedded Security Challenge. This contest focuses on memory corruption issues, such as stack overflow vulnerabilities. These low level vulnerabilities are the result of code errors. Once exploited, they allow an attacker to write arbitrary data in memory without limitations. We detail in this letter a hardware-based countermeasure against return address corruption in the processor stack. First, several exploitation techniques targeting stack return addresses are discussed, whereas a lightweight hardware countermeasure is proposed and validated on the OpenRISC core. The countermeasure presented follows the shadow stack concept with a minimal hardware modification of the targeted core and an easy integration at the application level.