3 ms·

I never got the impression that BIOS passwords were there to protect against attacks against adversaries who had full physical control of the machine to the ext

I never got the impression that BIOS passwords were there to protect against attacks against adversaries who had full physical control of the machine to the extent they had the case open, more like a casual layer or maybe if the machine was physically separate from the terminal IO. After all, at that point someone could just take your hard drive anyway right?

0xEF 3y ago
It was my understanding that the BIOS password was just one of many security layers that would ideally be in place in a protected environment, said layers being pretty effective when working in concert. My gripe is the eBay sellers and liquidators who want to sell a BIOS-locked laptop at full price. If a seller can't handle removing/resetting this password, then they shouldn't be selling it, or at the very least, list it as a $5 parts machine.
- mjg59 3y ago
  The BIOS password is a pretty meaningful protection - if it can be easily subverted it's possible to disable security features (such as IOMMU configuration for Thunderbolt devices in the boot environment) that allow an attacker to compromise the boot process. But I agree that there's no universe in which people should be selling devices that require unknown passwords as if they're generically usable.
  - gizmo686 3y ago
    We are talking about having physical access to the machine for long enough to partially dissasemble it and physically manipulate the mother board. There are a lot of attacks that enables, and almost no one even claims to defend against them. Put another way, a modern computer can be thought if as a network of relativity simple devices, of which the eeprom is one. Normally we assume that an attacker does not have access to this network. If the attacker does have access to this network, the game is lost. Everything about the network is unencrypted.
  - 0ct4via 3y ago
    This.
zokier 3y ago
> After all, at that point someone could just take your hard drive anyway right? With full-disk encryption, taking the hard drive is not that useful. Firmware passwords are one link in securing the boot chain; secure boot is meaningless if attacker can just modify firmware or its config. So the password should offer protection against evil maid style attacks.
- willis936 3y ago
  I'm not sure why this would be the case. Secret keys never leave security processors or data drives. The BIOS does very little here.
  - zokier 3y ago
    From firmware config you can potentially enroll new keys, or just disable sb completely, both which enable injecting malicious code in the boot chain
    - willis936 3y ago
      When changing security processors the secure boot drive requires the entry of the secret key again. If a user enters the secret key on a compromised system then the game would be up. You would need to wait until the user decided to change the security processor to intercept quietly.

0xEF 3y ago

It was my understanding that the BIOS password was just one of many security layers that would ideally be in place in a protected environment, said layers being pretty effective when working in concert. My gripe is the eBay sellers and liquidators who want to sell a BIOS-locked laptop at full price. If a seller can't handle removing/resetting this password, then they shouldn't be selling it, or at the very least, list it as a $5 parts machine.

mjg59 3y ago
The BIOS password is a pretty meaningful protection - if it can be easily subverted it's possible to disable security features (such as IOMMU configuration for Thunderbolt devices in the boot environment) that allow an attacker to compromise the boot process. But I agree that there's no universe in which people should be selling devices that require unknown passwords as if they're generically usable.
- gizmo686 3y ago
  We are talking about having physical access to the machine for long enough to partially dissasemble it and physically manipulate the mother board. There are a lot of attacks that enables, and almost no one even claims to defend against them. Put another way, a modern computer can be thought if as a network of relativity simple devices, of which the eeprom is one. Normally we assume that an attacker does not have access to this network. If the attacker does have access to this network, the game is lost. Everything about the network is unencrypted.
- 0ct4via 3y ago
  This.

zokier 3y ago

> After all, at that point someone could just take your hard drive anyway right? With full-disk encryption, taking the hard drive is not that useful. Firmware passwords are one link in securing the boot chain; secure boot is meaningless if attacker can just modify firmware or its config. So the password should offer protection against evil maid style attacks.

willis936 3y ago
I'm not sure why this would be the case. Secret keys never leave security processors or data drives. The BIOS does very little here.
- zokier 3y ago
  From firmware config you can potentially enroll new keys, or just disable sb completely, both which enable injecting malicious code in the boot chain
  - willis936 3y ago
    When changing security processors the secure boot drive requires the entry of the secret key again. If a user enters the secret key on a compromised system then the game would be up. You would need to wait until the user decided to change the security processor to intercept quietly.