Embedded Linux! Who needs security or new packages?

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Embedded Linux! Who needs security or new packages?

peepsalot: Apr 24, 2007; ��PEEP THIS...
��BITCH!

I have a beaglebone black and I used scp to transfer a file from my desktop to the beaglebone today. The beaglebone came from adafruit with debian pre-installed.

I sent it as root user, like: scp ./foo root@192.168.1.72:/home/debian/

I meant to do it as the default debian user, but wasn't thinking.
So anyways when I ran this command it didn't ask me for a password and just wrote the file as root for me. WTF?

e: i know there's some way to set up SSH keys or something so that you don't get prompted for pw, but I always forget how this works, and I'm pretty sure I never set this device up for that, sooo...

peepsalot fucked around with this message at 03:49 on Dec 20, 2016

# ¿ Dec 20, 2016 03:42

Adbot: ADBOT LOVES YOU

# ¿ May 16, 2024 13:01

peepsalot: Apr 24, 2007; ��PEEP THIS...
��BITCH!

Storysmith posted:

Try running (as root)
code:
cat /root/.ssh/authorized_keys

code:

cat: /root/.ssh/authorized_keys: No such file or directory

there is no .ssh dir under /root at all

Storysmith posted:

Adding more levels of -v flags to get more debug output will shine some light as to how auth (if any) is happening.

code:

peeps@peeps-ThinkPad-W510:~$ touch foo
peeps@peeps-ThinkPad-W510:~$ scp -v foo root@192.168.1.72:/home/debian/
Executing: program /usr/bin/ssh host 192.168.1.72, user root, command scp -v -t /home/debian/
OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to 192.168.1.72 [192.168.1.72] port 22.
debug1: Connection established.
debug1: identity file /home/peeps/.ssh/id_rsa type 1
debug1: identity file /home/peeps/.ssh/id_rsa-cert type -1
debug1: identity file /home/peeps/.ssh/id_dsa type -1
debug1: identity file /home/peeps/.ssh/id_dsa-cert type -1
debug1: identity file /home/peeps/.ssh/id_ecdsa type -1
debug1: identity file /home/peeps/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/peeps/.ssh/id_ed25519 type -1
debug1: identity file /home/peeps/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.0p1 Debian-4+deb7u6
debug1: match: OpenSSH_6.0p1 Debian-4+deb7u6 pat OpenSSH* compat 0x04000000
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 74:4c:b9:73:85:62:82:f9:c7:17:5d:9f:72:b1:e9:8f
debug1: Host '192.168.1.72' is known and matches the ECDSA host key.
debug1: Found key in /home/peeps/.ssh/known_hosts:31
debug1: ssh_ecdsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
Debian GNU/Linux 7

BeagleBoard.org Debian Image 2015-11-12

Support/FAQ: [url]http://elinux.org/Beagleboard:BeagleBoneBlack_Debian[/url]

default username:password is [debian:temppwd]

debug1: Authentication succeeded (none).
Authenticated to 192.168.1.72 ([192.168.1.72]:22).
debug1: channel 0: new [client-session]
debug1: Requesting [email]no-more-sessions@openssh.com[/email]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LC_PAPER = en_US.UTF-8
debug1: Sending env LC_ADDRESS = en_US.UTF-8
debug1: Sending env LC_MONETARY = en_US.UTF-8
debug1: Sending env LC_NUMERIC = en_US.UTF-8
debug1: Sending env LC_TELEPHONE = en_US.UTF-8
debug1: Sending env LC_IDENTIFICATION = en_US.UTF-8
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending env LC_MEASUREMENT = en_US.UTF-8
debug1: Sending env LC_TIME = en_US.UTF-8
debug1: Sending env LC_NAME = en_US.UTF-8
debug1: Sending command: scp -v -t /home/debian/
Sending file modes: C0644 0 foo
Sink: C0644 0 foo
foo                                                                                                                                         100%    0     0.0KB/s   00:00
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
Transferred: sent 3040, received 1856 bytes, in 0.1 seconds
Bytes per second: sent 34492.5, received 21058.6
debug1: Exit status 0

# ¿ Dec 21, 2016 18:22

peepsalot: Apr 24, 2007; ��PEEP THIS...
��BITCH!

Storysmith posted:

Well there's your answer. Apparently out of the box, it doesn't require auth for root access for some reason. I'll need to see if I still have my BBB to play with, but that's hilarious.

Ok well i just spent an inordinate amount of time looking into this for reasons I can't quite explain, but it looks like the issue is a combination of things

First I found that root password is blank ( /etc/shadow shows root:: )
Is this typical for debian based systems that use sudo to escalate privileges anyways?

But when you combine that empty password with these settings in /etc/ssh/sshd_config
PermitRootLogin yes
and
PermitEmptyPasswords yes

Then it just lets you ssh with no password. I found that changing just the PermitEmptyPasswords option to no is enough to stop this behavior.

I guess I'm just curious if this sort of blank root password setup could cause other security issues outside of ssh/scp.
And just still generally confused about how this whole sudo situation with no actual root password is *supposed* to work in a secure manner.

peepsalot fucked around with this message at 02:31 on Dec 22, 2016

# ¿ Dec 22, 2016 02:28

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Embedded Linux! Who needs security or new packages?