libu8ident VS Confusables

In programming languages it's much worse. Identifiers can either be unidentifiable, and if so everybody has a different opinion what "identifiable" means. Even the standard on identifiers, UTF-39, is buggy and has too many interpretations, leading to a complete disaster. https://github.com/rurban/libu8ident/blob/master/doc/c11.md

In punycode domain names it's quite simple still.

With other names, it's even worse. No-one cares. Linkers do not, username and filesystem drivers do not. The Apple HFS+ did care a bit one day, until someone in the higher ranks decided that no-one needs unicode security anymore and switched the new APFS to unsafe again.

No, it's definitely not safe to use unrestricted Unicode in a compiler. See https://github.com/rurban/libu8ident/ for identifier rules, and http://www.unicode.org/reports/tr55/ for much worse problems.

That's why unicode published the security guidelines and mechanisms to avoid such attacks. In 2004 already.

The problem is that nobody cared. Browsers invented punycode instead of following tr39, email ditto. But ok, at least something. Java did it, cperl did, rust did it.

Everybody else is vulnerable. Esp. most other programming languages, filesystems and login systems. https://github.com/rurban/libu8ident/blob/master/doc/c11.md

I'm maintaining such a library.

coreutils, diff, grep, patch, sed and friends all cannot find Unicode strings, they have no string support. They can only mimic filesystems, finding binary garbage. Strings are so rthi g different than pure ASCII or BINARY garbage. Strings have an encoding and are Unicode.

Filesystems are even worse because they need to treat filenames as identifiers, but do not. Nobody cares about TR31, TR39, TR36 and so on.

Here is an overview of the sad state of Unicode unsafeties in programming languages: https://github.com/rurban/libu8ident/blob/master/c11.md

I wrote a small python library for searching obfuscated Unicode text by creating regex expressions; our company’s chat was being overrun by spammers.

https://github.com/wanderingstan/Confusables

From the readme:

E.g. "℮1೦" would match "Hello"

"Hello" gets turned into the following regex of character classes:

  [HＨℋℌℍΗⲎНᎻᕼꓧ𐋏ⱧҢĦӉӇ]

You're right. The code was correct but the Readme hadn't been updated to reflect the lack of backslashes. Thanks for the find!

https://github.com/wanderingstan/Confusables/commit/c4121428...

I built a Python library for finding strings obfuscated this way. Was critical when moderating our telegram channel before an ICO.

https://github.com/wanderingstan/Confusables

E.g. "𝓗℮𝐥1೦" would match "Hello"