The following command works even though I really don’t think I should have permission to the key file:
$ openssl aes-256-cbc -d -pbkdf2 -in etc_backup.tar.xz.enc -out etc_backup.tar.xz -k /etc/ssl/private/etcBackup.key

I’m unable to even ascertain the existence of the key file under my normal user. I’m a member of only two groups, my own group and vboxusers.

The permissions leading up to that file:

drwxr-xr-x   1 root root 4010 Jul 31 08:01 etc
...
drwxr-xr-x 1 root root      206 Jul 14 23:52 ssl
...
drwx------ 1 root root    26 Jul 31 14:07 private
...
-rw------- 1 root root 256 Jul 31 14:07 etcBackup.key

OpenSSL isn’t setuid:

> ls -la $(which openssl)
-rwxr-xr-x 1 root root 1004768 Jul 14 23:52 /usr/bin/openssl

There don’t appear to be any ACLs related to that key file:

> sudo getfacl /etc/ssl/private/etcBackup.key
[sudo] password for root: 
getfacl: Removing leading '/' from absolute path names
# file: etc/ssl/private/etcBackup.key
# owner: root
# group: root
user::rw-
group::---
other::---

> sudo lsattr  /etc/ssl/private/etcBackup.key
---------------------- /etc/ssl/private/etcBackup.key

Finally, it’s not just the case that the original file was encrypted with an empty file:

> openssl aes-256-cbc -d -pbkdf2 -in etc_backup.tar.xz.enc -out etc_backup.tar.xz -k /etc/ssl/private/abc.key
bad decrypt
4047F634B67F0000:error:1C800064:Provider routines:ossl_cipher_unpadblock:bad decrypt:providers/implementations/ciphers/ciphercommon_block.c:124

Does anyone know what I’ve missed here?

  • ghjones@beehaw.org
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    3 months ago

    Just to verify all permission-related things in one go, see if you can open the key as your user with an editor like vi or nano. This will let you separate out some behavior specific to OpenSSL vs some behavior purely permissions-based.

    I’m not sure what’s happening here, but the above test can at least narrow the focus.