# Re: \[PATCH v8 0/8\] Fork brute force attack mitigation

- From: Kees Cook \<hidden\>
- Date: 2021-06-08 23:20:49 
- List: linux-security-module
- Page: https://ratatoskr.run/linux-security-module/2021/06/1407703
- Thread: https://ratatoskr.run/linux-doc/2021/06/1403571/t.md

```text
On Sat, Jun 05, 2021 at 05:03:57PM +0200, John Wood wrote:
> [...]
> the kselftest to avoid the detection ;) ). So, in this version, to track
> all the statistical data (info related with application crashes), the
> extended attributes feature for the executable files are used. The xattr is
> also used to mark the executables as "not allowed" when an attack is
> detected. Then, the execve system call rely on this flag to avoid following
> executions of this file.

I have some concerns about this being actually usable and not creating
DoS situations. For example, let's say an attacker had found a hard-to-hit
bug in "sudo", and starts brute forcing it. When the brute LSM notices,
it'll make "sudo" unusable for the entire system, yes?

And a reboot won't fix it, either, IIUC.

It seems like there is a need to track "user" running "prog", and have
that be timed out. Are there use-cases here where that wouldn't be
sufficient?

-Kees

-- 
Kees Cook
```