Mission 0x20

🔎 Solution

After logging in as eliza, the next hint suggested that the upcoming access wouldn't require a password but rather a stored key.

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# MISSION 0x20 #
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## EN ##
The user iris has left me her key.

Checking the home directory revealed a private OpenSSH key:

eliza@venus:~$ cat .iris_key 
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAABlwAAAAdzc2gtcn
NhAAAAAwEAAQAAAYEAstTtUVotXEIF5+w37pKse/YGLEMMMnMB2DQQ1EF/KP7ey72FhO9S
Jk4wPtBZ6+pPKefUA2uSJHGhHia++uBOcuWt3SAdR5gUqxpdFTgYqZczWEgCDoY/L0rUQG

Since this is a private key, SSH can use it for authentication - but only if the file permissions are secure. SSH refuses to use keys that are readable by others, so the permission needs to be restricted:

chmod 600 .iris_key 

With the permissions fixed, the login attempt worked:

ssh -i .iris_key iris@venus.hackmyvm.eu -p 5000 

Inside iris's account, the flag was waiting as usual:

iris@venus:~$ cat flagz.txt 
8===ClrdWOqlZ1vL61zSk9Va===D~~

🚩Flag

8===ClrdWOqlZ1vL61zSk9Va===D~~