22C3 - 2.2

22nd Chaos Communication Congress
Private Investigations

Marc Schiesser
Tag 3
Raum Saal 3
Beginn 11:00
Dauer 01:00
ID 1139
Veranstaltungstyp Vortrag
Track Hacking
Sprache englisch

COMPLETE Hard Disk Encryption with FreeBSD

Learn how to effectively protect not only your data but also your applications

Most technologies and techniques intended for securing digital data focus on protection while the machine is turned on – mostly by defending against remote attacks. An attacker with physical access to the machine, however, can easily circumvent these defenses by reading out the contents of the storage medium on a different, fully accessible system or even compromise program code on it in order to leak encrypted information. Especially for mobile users, that threat is real. And for those carrying around sensitive data, the risk is most likely high. This talk will introduce a method of mitigating that particular risk by protecting not only the data through encryption, but also the applications and the operating system from being compromised while the machine is turned off.

====Securing digital data====

When is comes to securing digital data, a lot of resources are usually spent on mitigating the risk of network-based attacks: encrypt transmissions, apply patches, harden network stacks and use firewalls and an IDS. All these countermeasures are without doubt justified – even more so as more and more devices become networked.

However, all defenses against network-based attacks are useless if the attacker can simply read out the contents of the hard disk(s) from a (usually) different system – which brings us to in-storage data encryption.

====The problem with partial encryption====

Even if storage encryption is used, it is often less effective than it is perceived to be – because a lot of programs "leak" data to unencrypted parts of the medium by creating temporary copies of the files you are working on.

Aside from thus giving the user a false sense of security, both the file-based and the partition-based encryption approach suffer from a major problem: the operating system remains unencrypted.

====Mobile users at particular risk====

With today's cipher-strengths in mind, pretty much anything is easier than a brute-force attack against the encrypted data (a strong key provided). So, if the attacker has physical access to the hard disk, compromising the OS or the applications seems like the easiest way to get the data.

The implication is that, unless you keep your computer in sight at all times, you cannot really be sure it has not been compromised. But as a mobile user you obviously do not want to carry your notebook on you all day long.

The goal is therefore to encrypt the entire hard disk, so that physical access to the device offers no realistic chance for a (software) compromise.

====Core issues discussed in this talk====

The talk will be divided into three main subjects:

  • Background & motivation: explains the need for in-storage data encryption and discusses partial disk encryption and the motivation behind complete disk encryption.
  • Implementation: details of how to implement complete disk encryption on a FreeBSD system. The solution relies on standard FreeBSD tools and does not involve programming.
  • Implications: explains what is and is not protected by complete disk encryption. New risks, dangers as well as trade-offs will also be discussed.
Part II will be technical and aimed mainly at experienced UNIX users. Parts I & III discuss general issues regarding complete disk encryption and should therefore also be interesting to a broader audience.