The research and hacks that went into discovering this impresses me.
“Therefore, by placing Bidi override characters exclusively within comments and strings, we can smuggle them into source code in a manner that most compilers will accept. Our key insight is that we can reorder source code characters in such a way that the resulting display order also represents syntactically valid source code.”
“Bringing all this together, we arrive at a novel supply-chain attack on source code. By injecting Unicode Bidi override characters into comments and strings, an adversary can produce syntactically-valid source code in most modern languages for which the display order of characters presents logic that diverges from the real logic. In effect, we anagram program A into program B.”
“Therefore, by placing Bidi override characters exclusively within comments and strings, we can smuggle them into source code in a manner that most compilers will accept. Our key insight is that we can reorder source code characters in such a way that the resulting display order also represents syntactically valid source code.”
“Bringing all this together, we arrive at a novel supply-chain attack on source code. By injecting Unicode Bidi override characters into comments and strings, an adversary can produce syntactically-valid source code in most modern languages for which the display order of characters presents logic that diverges from the real logic. In effect, we anagram program A into program B.”
