Ropt

Ropt, also known as return-oriented programming, is a sophisticated computer security exploit technique. It allows an attacker to execute code on a target system even when protections like non-executable memory (NX bit) are in place. Instead of injecting entirely new malicious code, ropt attackers leverage existing code snippets already present in the program's memory, known as "gadgets."

These gadgets are typically small sequences of instructions that end with a return instruction. By chaining together these existing gadgets in a specific order, an attacker can construct arbitrary functionality. The attacker carefully chooses and chains these gadgets to perform desired operations, such as making system calls or manipulating data. The return instruction at the end of each gadget allows the execution flow to jump to the next gadget in the chain.

The effectiveness of ropt relies on the attacker's ability to control the program's instruction pointer and carefully craft the sequence of gadget addresses. This often involves exploiting a buffer overflow vulnerability to overwrite the return address on the stack. Modern systems employ various defenses against ropt, including address space layout randomization (ASLR) which makes it harder for attackers to predict gadget addresses, and control-flow integrity (CFI) which aims to ensure that execution follows a predefined, valid control flow graph. Despite these defenses, ropt remains a significant threat in the cybersecurity landscape.