Bitsquatting attacks and exploitation with Rust

I personally find bitsquatting attacks mind-blowing!

The idea is that computers suffer from memory errors where one or more bits are corrupted, they are different than their expected value. It can come from electromagnetic interference or cosmic rays (!).

This post is an excerpt from my book Black Hat Rust

A bit that is expected to be 0, may flips to 1, and vice versa.

In this example, if attackers control acc.com, they may receive originally destined for abc.com without any human error!

Here is a small program to generate all the "bitshifted" and valid alternatives of a given domain:
ch_09/dnsquat/src/main.rs

use std::env;

fn bitflip(charac: u8, pos: u8) -> u8 {
    let shiftval = 1 << pos;
    charac ^ shiftval
}

fn is_valid(charac: char) -> bool {
    charac.is_ascii_alphanumeric() || charac == '-'
}

fn main() {
    let args = env::args().collect::<Vec<String>>();
    if args.len() != 3 {
        println!("Usage: dnsquat domain .com");
        return;
    }

    let name = args[1].to_lowercase();
    let tld = args[2].to_lowercase();

    for i in 0..name.len() {
        let charac = name.as_bytes()[i];
        for bit in 0..8 {
            let bitflipped = bitflip(charac.into(), bit);
            if is_valid(bitflipped as char)
                && bitflipped.to_ascii_lowercase() != charac.to_ascii_lowercase()
            {
                let mut bitsquatting_candidat = name.as_bytes()[..i].to_vec();
                bitsquatting_candidat.push(bitflipped);
                bitsquatting_candidat.append(&mut name.as_bytes()[i + 1..].to_vec());

                println!(
                    "{}{}",
                    String::from_utf8(bitsquatting_candidat).unwrap(),
                    tld
                );
            }
        }
    }
}

$ cargo run -- domain .com
eomain.com
fomain.com
lomain.com
tomain.com
dnmain.com
dmmain.com
dkmain.com
dgmain.com
dolain.com
dooain.com
doiain.com
doeain.com
do-ain.com
domcin.com
domein.com
domiin.com
domqin.com
domahn.com
domakn.com
domamn.com
domaan.com
domayn.com
domaio.com
domail.com
domaij.com
domaif.com