2 explained why an encrypted hdd is not 100% secure
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You pretty much hit the nail on the head when you said that you need physical access to the machine.

If you have physical access, you don't need to go through the official steps to reset the root password, as you can flips bits on the hard drive directly, if you know what you're doing. I.e., you can boot up a recovery OS from a DVD or flash drive, and mount the drive that way to gain complete read/write access to the entire disk.

Disk encryption will mitigate the risk, but doesn't remove it entirelyentirely* but makes attacks much more complicated. It is best to assume that an attacker with physical access will be able to influence every aspect of the device in time.

Since it's assumed that attackers with physical access will always gain privileged account access eventually, there's little point in putting the legitimate administrators through extra trouble if they lost their password.

Every Linux distro that I have used has had this feature, though it's possible that some of the distros aimed at a more paranoid audience could disable this.

In addition, it's a standard feature in BSD Unixes, was tested for on the CCNA exam at least 15 years ago when I took it for Cisco devices, and it's fairly trivial to reset passwords on a Windows machine if it isn't explicitly secured.

* The attacker could for example add a backdoored kernel or initrd in the /boot directory, that needs to be unencrypted because the bootloader must be able to read the kernel and initrd files.

You pretty much hit the nail on the head when you said that you need physical access to the machine.

If you have physical access, you don't need to go through the official steps to reset the root password, as you can flips bits on the hard drive directly, if you know what you're doing. I.e., you can boot up a recovery OS from a DVD or flash drive, and mount the drive that way to gain complete read/write access to the entire disk.

Disk encryption will mitigate the risk, but doesn't remove it entirely. It is best to assume that an attacker with physical access will be able to influence every aspect of the device in time.

Since it's assumed that attackers with physical access will always gain privileged account access eventually, there's little point in putting the legitimate administrators through extra trouble if they lost their password.

Every Linux distro that I have used has had this feature, though it's possible that some of the distros aimed at a more paranoid audience could disable this.

In addition, it's a standard feature in BSD Unixes, was tested for on the CCNA exam at least 15 years ago when I took it for Cisco devices, and it's fairly trivial to reset passwords on a Windows machine if it isn't explicitly secured.

You pretty much hit the nail on the head when you said that you need physical access to the machine.

If you have physical access, you don't need to go through the official steps to reset the root password, as you can flips bits on the hard drive directly, if you know what you're doing. I.e., you can boot up a recovery OS from a DVD or flash drive, and mount the drive that way to gain complete read/write access to the entire disk.

Disk encryption will mitigate the risk, but doesn't remove it entirely* but makes attacks much more complicated. It is best to assume that an attacker with physical access will be able to influence every aspect of the device in time.

Since it's assumed that attackers with physical access will always gain privileged account access eventually, there's little point in putting the legitimate administrators through extra trouble if they lost their password.

Every Linux distro that I have used has had this feature, though it's possible that some of the distros aimed at a more paranoid audience could disable this.

In addition, it's a standard feature in BSD Unixes, was tested for on the CCNA exam at least 15 years ago when I took it for Cisco devices, and it's fairly trivial to reset passwords on a Windows machine if it isn't explicitly secured.

* The attacker could for example add a backdoored kernel or initrd in the /boot directory, that needs to be unencrypted because the bootloader must be able to read the kernel and initrd files.

1
source | link

You pretty much hit the nail on the head when you said that you need physical access to the machine.

If you have physical access, you don't need to go through the official steps to reset the root password, as you can flips bits on the hard drive directly, if you know what you're doing. I.e., you can boot up a recovery OS from a DVD or flash drive, and mount the drive that way to gain complete read/write access to the entire disk.

Disk encryption will mitigate the risk, but doesn't remove it entirely. It is best to assume that an attacker with physical access will be able to influence every aspect of the device in time.

Since it's assumed that attackers with physical access will always gain privileged account access eventually, there's little point in putting the legitimate administrators through extra trouble if they lost their password.

Every Linux distro that I have used has had this feature, though it's possible that some of the distros aimed at a more paranoid audience could disable this.

In addition, it's a standard feature in BSD Unixes, was tested for on the CCNA exam at least 15 years ago when I took it for Cisco devices, and it's fairly trivial to reset passwords on a Windows machine if it isn't explicitly secured.