this post was submitted on 31 Jul 2024
51 points (100.0% liked)

Linux

48178 readers
1093 users here now

From Wikipedia, the free encyclopedia

Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

Rules

Related Communities

Community icon by Alpár-Etele Méder, licensed under CC BY 3.0

founded 5 years ago
MODERATORS
AgreeableLandscape@lemmy.ml
nooter692@lemmy.ml
MarcellusDrum@lemmy.ml
cypherpunks@lemmy.ml
cyclohexane@lemmy.ml
d3Xt3r@lemmy.nz
51
Why is OpenSSL able to use a key file my user shouldn't have access to? (lemmy.ca)
submitted 3 months ago by NotAnArdvark@lemmy.ca to c/linux@lemmy.ml
8 comments fedilink hide all child comments
 

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?

you are viewing a single comment's thread
view the rest of the comments
[–] Maxy@lemmy.blahaj.zone 9 points 3 months ago (2 children)

I have about 0 experience with openssl, I just looked at the man page (openssl-enc). It looks like this command doesn’t take a positional argument. I believe the etcBackup.key file isn’t being read, as that command simply doesn’t attempt to read any files without a flag like -in or -out. I could be wrong though, see previously stated inexperience.

[–] metiulekm@sh.itjust.works 12 points 3 months ago (1 children)

It seems OP wanted to pass the file name to -k, but this parameter takes the password itself and not a filename:

       -k password
           The password to derive the key from. This is for compatibility with previous versions of OpenSSL. Superseded by the -pass argument.

So, as I understand, the password would be not the first line of /etc/ssl/private/etcBackup.key, but the string /etc/ssl/private/etcBackup.key itself. It seems that -kfile /etc/ssl/private/etcBackup.key or -pass file:/etc/ssl/private/etcBackup.key is what OP wanted to use.

[–] refalo@programming.dev 11 points 3 months ago

Oh that's nasty. I bet a quick github search would turn up some people making the same mistake.

[–] hnh@beehaw.org 2 points 3 months ago

Almost. -k is to supply the passphrase directly, while -kfile does what OP believes -k does. That's why it reports "bad decrypt" as well.