Hi Larsen,Thank you so much for your reply.Your answer raised other questions in my mind.
What do you mean by "Giving the program unexpected or malicious inputs."? Do you mean Fuzzing?
Please take a look at these vulnerabilities:
https://www.cvedetails.com/cve/CVE-2022-31705/

https://www.cvedetails.com/cve/CVE-2023-32209/

What technique did the person who found these vulnerabilities use? Debugging or Reverse Engineering?


 
 
  On Sun, Sep 24, 2023 at 4:53 PM, Guinevere Larsen<blarsen@redhat.com> wrote:   On 24/09/2023 15:09, Jason Long via Gdb wrote:
> Hello folks,I have two questions:
Hello, thanks for the questions!
> 1- Can a debugger like GDB be used to find the vulnerability?

Yes, you could use GDB to find some security vulnerabilities, though it 
is hardly the best tool for this job. The kind of stuff you'd find with 
GDB is a logic mistake that leads to information leaks or similar. In my 
experience, though, GDB is more useful to look at one unexpected 
behavior and figure out if that leads to a security vulnerability or 
not, rather than going form scratch and giving the program unexpected or 
malicious inputs.

>
> 2- When a hacker finds a vulnerability in a program, has that hacker used debugging techniques or reverse engineering?

Reverse engineering doesn't necessarily have to do with security. 
Reverse engineering is the act of getting something that is not 
understood and trying to understand it without having access to any kind 
of documentation. I don't recommend running unknown binaries in your 
machine, since GDB doesn't provide any security, but if you are doing 
that, stepping slowly and trying to understand how the program works, 
you are doing reverse engineering. It doesn't have to relate at all to 
security.

With that in mind, the answer to your question is "it depends". The 
stuff you can find with GDB alone will always involve debugging 
techinques, but with regards to reverse engineering techniques, the 
question is does the vulnerability come in from the fact that the 
attacker knows the internal mechanisms for the program or not? If it 
does, then yes you could say you found a vulnerability by reverse 
engineering.

> Any idea welcomed.
>
> Thank you.
>
I hope this helps!

-- 
Cheers,
Guinevere Larsen
She/Her/Hers