Starting point: Privilege escalation - Invalid id_rsa format

HTB Content Machines
1

Hello,

in the Privilege escalation target machine I’ve copied id_rsa key, create a new file, pasted the id_rsa copied from the host machine. Then I performed chmod 600 id_rsa. Finally I am trying to use ssh root@hostip -p hostport -i id_rsa and I get the following error:

Load key "id_rsa": invalid format

I’ve seen similar examples like Topics tagged starting-point, the solution provided was to use puttygen, however, the puttygen command also throws an error that it’s not the private key. Checking the file using file id_rsa shows as OpenSSH private key.

I’ve checked multiple times, checked the size, characters count from the host machine and my current id_rsa - everything is fine.

Not sure what to do. Thanks.

2

…I’ve copied id_rsa key, create a new file, pasted the id_rsa copied from the host machine.

Why?
The files has grp set to user2, so you can copy the id_rsa into authorize_key into you home/.ssh. Put the chmod 600 and stop, now you can escalation the privs

3

Hi, not sure I understood your comment, but I did everything again the same way I did yesterday - copied the host id_rsa to local machine and used ssh root@hostip -p hostport -i id_rsa and it worked. Maybe something was wrong with the machine, cannot tell exactly.

4

sometimes machine get off…reset option is useful. Its best to check “ping”

5

Maybe something was wrong with the machine, cannot tell exactly.

Sure :v:

For example a copy can corrupt a file.