Using bidirectionality override characters to obscure code.

Guests Nicholas Boucher and Ross Anderson from the University of Cambridge join Dave Bittner to discuss their research, "Trojan Source: Invisible Vulnerabilities." The researchers present a new type of attack in which source code is maliciously encoded so that it appears different to a compiler and to the human eye. This attack exploits subtleties in text-encoding standards such as Unicode to produce source code whose tokens are logically encoded in a different order from the one in which they are displayed, leading to vulnerabilities that cannot be perceived directly by human code reviewers. ‘Trojan Source’ attacks, as they call them, pose an immediate threat both to first-party software and of supply-chain compromise across the industry. They present working examples of Trojan-Source attacks in C, C++, C#, JavaScript, Java, Rust, Go, and Python. They propose definitive compiler-level defenses, and describe other mitigating controls that can be deployed in editors, repositories, and build pipelines while compilers are upgraded to block this attack. The project website and research can be found here: Trojan Source: Invisible Source Code Vulnerabilities project website Trojan Source: Invisible Vulnerabilities research paper