Insecure sdmem command

[Lvl4Sword]

According to the sdmem manual page:

-f     fast (and insecure mode): no /dev/urandom.

-l     lessens the security. Only two passes  are  written:  the  first
              with 0x00 and a final random one.

-l     -l  for  a  second time lessons the security even more: only one
              pass with 0x00 is written.

When the command is sdmem -fll, I don't see how this could protect against something like https://blog.f-secure.com/cold-boot-attacks/

[cyian-1756]

When the command is sdmem -fll, I don't see how this could protect against something like

The memory is still overwritten, it's just done in one pass and with 0s instead of random data. However usbkill doesn't offer much to protect against coldboot attacks considering that they attacks don't require a usb be inserted into the target machine when the machine is running