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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
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view the system memory in clear text

Terminal - view the system memory in clear text
hexdump -e '90/1 "%_p" "\n"' /dev/mem | less
2009-05-12 16:20:57
User: copremesis
Functions: hexdump
view the system memory in clear text

see what's in your memory right now... sometimes you find passwords, account numbers and url's that were recently used. Anyone have a safe command to clear the memory without rebooting?


There is 1 alternative - vote for the best!

Terminal - Alternatives

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What others think

Of course access to /dev/mem depends on being root or being in the 'kmem' group (on my ubuntu system). But then when accessing memory raw like that as a user, you have no idea whether a particular physical address is currently in use because you do not have access to the kernel's data structures (even as root) if you're thinking of writing to that memory for the purposes of 'clearing' it. At least that's my understanding.

This memory scrubbing is probably best done at the application level, and many applications where security matters a bit more do take steps to clear memory areas before freeing them.

Also, rebooting doesn't necessarily clear the contents of memory: http://en.wikipedia.org/wiki/Cold_boot_attack

Comment by bwoodacre 467 weeks ago

/dev/mem should already be restricted to only root or the wheel group ... and if someone untrusted already has root access, you have worse things to worry about than someone sifting through active memory.

Comment by Mozai 333 weeks and 1 day ago

It's unnecessary for reasons as noted above and you can't and obviously shouldn't go mucking about in addresses that are allocated for shared or running programs.

But.. for the sake of argument, or if you are just super paranoid, this task is as simple as allocating memory. You can write a simple c/c++ program to call malloc() to allocate a large bit of memory and initialize it with 0's or garbage data then terminate.

Comment by egreSS 232 weeks and 2 days ago

Your point of view

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