cloud computing Archives - Schneier on Security

Entries Tagged "cloud computing"

Page 1 of 9

New Attacks Against Secure Enclaves

Encryption can protect data at rest and data in transit, but does nothing for data in use. What we have are secure enclaves. I’ve written about this before:

Almost all cloud services have to perform some computation on our data. Even the simplest storage provider has code to copy bytes from an internal storage system and deliver them to the user. End-to-end encryption is sufficient in such a narrow context. But often we want our cloud providers to be able to perform computation on our raw data: search, analysis, AI model training or fine-tuning, and more. Without expensive, esoteric techniques, such as secure multiparty computation protocols or homomorphic encryption techniques that can perform calculations on encrypted data, cloud servers require access to the unencrypted data to do anything useful.

Fortunately, the last few years have seen the advent of general-purpose, hardware-enabled secure computation. This is powered by special functionality on processors known as trusted execution environments (TEEs) or secure enclaves. TEEs decouple who runs the chip (a cloud provider, such as Microsoft Azure) from who secures the chip (a processor vendor, such as Intel) and from who controls the data being used in the computation (the customer or user). A TEE can keep the cloud provider from seeing what is being computed. The results of a computation are sent via a secure tunnel out of the enclave or encrypted and stored. A TEE can also generate a signed attestation that it actually ran the code that the customer wanted to run.

Secure enclaves are critical in our modern cloud-based computing architectures. And, of course, they have vulnerabilities:

The most recent attack, released Tuesday, is known as TEE.fail. It defeats the latest TEE protections from all three chipmakers. The low-cost, low-complexity attack works by placing a small piece of hardware between a single physical memory chip and the motherboard slot it plugs into. It also requires the attacker to compromise the operating system kernel. Once this three-minute attack is completed, Confidential Compute, SEV-SNP, and TDX/SDX can no longer be trusted. Unlike the Battering RAM and Wiretap attacks from last month—which worked only against CPUs using DDR4 memory—TEE.fail works against DDR5, allowing them to work against the latest TEEs.

Yes, these attacks require physical access. But that’s exactly the threat model secure enclaves are supposed to secure against.

Posted on November 10, 2025 at 7:04 AM • View Comments

UK Is Ordering Apple to Break Its Own Encryption

The Washington Post is reporting that the UK government has served Apple with a “technical capability notice” as defined by the 2016 Investigatory Powers Act, requiring it to break the Advanced Data Protection encryption in iCloud for the benefit of law enforcement.

This is a big deal, and something we in the security community have worried was coming for a while now.

The law, known by critics as the Snoopers’ Charter, makes it a criminal offense to reveal that the government has even made such a demand. An Apple spokesman declined to comment.

Apple can appeal the U.K. capability notice to a secret technical panel, which would consider arguments about the expense of the requirement, and to a judge who would weigh whether the request was in proportion to the government’s needs. But the law does not permit Apple to delay complying during an appeal.

In March, when the company was on notice that such a requirement might be coming, it told Parliament: “There is no reason why the U.K. [government] should have the authority to decide for citizens of the world whether they can avail themselves of the proven security benefits that flow from end-to-end encryption.”

Apple is likely to turn the feature off for UK users rather than break it for everyone worldwide. Of course, UK users will be able to spoof their location. But this might not be enough. According to the law, Apple would not be able to offer the feature to anyone who is in the UK at any point: for example, a visitor from the US.

And what happens next? Australia has a law enabling it to ask for the same thing. Will it? Will even more countries follow?

This is madness.

Posted on February 8, 2025 at 10:56 AM • View Comments

Decoupling for Security

This is an excerpt from a longer paper. You can read the whole thing (complete with sidebars and illustrations) here.

Our message is simple: it is possible to get the best of both worlds. We can and should get the benefits of the cloud while taking security back into our own hands. Here we outline a strategy for doing that.

What Is Decoupling?

In the last few years, a slew of ideas old and new have converged to reveal a path out of this morass, but they haven’t been widely recognized, combined, or used. These ideas, which we’ll refer to in the aggregate as “decoupling,” allow us to rethink both security and privacy.

Here’s the gist. The less someone knows, the less they can put you and your data at risk. In security this is called Least Privilege. The decoupling principle applies that idea to cloud services by making sure systems know as little as possible while doing their jobs. It states that we gain security and privacy by separating private data that today is unnecessarily concentrated.

To unpack that a bit, consider the three primary modes for working with our data as we use cloud services: data in motion, data at rest, and data in use. We should decouple them all.

Our data is in motion as we exchange traffic with cloud services such as videoconferencing servers, remote file-storage systems, and other content-delivery networks. Our data at rest, while sometimes on individual devices, is usually stored or backed up in the cloud, governed by cloud provider services and policies. And many services use the cloud to do extensive processing on our data, sometimes without our consent or knowledge. Most services involve more than one of these modes.

To ensure that cloud services do not learn more than they should, and that a breach of one does not pose a fundamental threat to our data, we need two types of decoupling. The first is organizational decoupling: dividing private information among organizations such that none knows the totality of what is going on. The second is functional decoupling: splitting information among layers of software. Identifiers used to authenticate users, for example, should be kept separate from identifiers used to connect their devices to the network.

In designing decoupled systems, cloud providers should be considered potential threats, whether due to malice, negligence, or greed. To verify that decoupling has been done right, we can learn from how we think about encryption: you’ve encrypted properly if you’re comfortable sending your message with your adversary’s communications system. Similarly, you’ve decoupled properly if you’re comfortable using cloud services that have been split across a noncolluding group of adversaries.

Read the full essay

This essay was written with Barath Raghavan, and previously appeared in IEEE Spectrum.

Posted on November 8, 2023 at 7:08 AM • View Comments

LastPass Breach

Last August, LastPass reported a security breach, saying that no customer information—or passwords—were compromised. Turns out the full story is worse:

While no customer data was accessed during the August 2022 incident, some source code and technical information were stolen from our development environment and used to target another employee, obtaining credentials and keys which were used to access and decrypt some storage volumes within the cloud-based storage service.

[…]

To date, we have determined that once the cloud storage access key and dual storage container decryption keys were obtained, the threat actor copied information from backup that contained basic customer account information and related metadata including company names, end-user names, billing addresses, email addresses, telephone numbers, and the IP addresses from which customers were accessing the LastPass service.

The threat actor was also able to copy a backup of customer vault data from the encrypted storage container which is stored in a proprietary binary format that contains both unencrypted data, such as website URLs, as well as fully-encrypted sensitive fields such as website usernames and passwords, secure notes, and form-filled data.

That’s bad. It’s not an epic disaster, though.

These encrypted fields remain secured with 256-bit AES encryption and can only be decrypted with a unique encryption key derived from each user’s master password using our Zero Knowledge architecture. As a reminder, the master password is never known to LastPass and is not stored or maintained by LastPass.

So, according to the company, if you chose a strong master password—here’s my advice on how to do it—your passwords are safe. That is, you are secure as long as your password is resilient to a brute-force attack. (That they lost customer data is another story….)

Fair enough, as far as it goes. My guess is that many LastPass users do not have strong master passwords, even though the compromise of your encrypted password file should be part of your threat model. But, even so, note this unverified tweet:

I think the situation at @LastPass may be worse than they are letting on. On Sunday the 18th, four of my wallets were compromised. The losses are not significant. Their seeds were kept, encrypted, in my lastpass vault, behind a 16 character password using all character types.

If that’s true, it means that LastPass has some backdoor—possibly unintentional—into the password databases that the hackers are accessing. (Or that @Cryptopathic’s “16 character password using all character types” is something like “P@ssw0rdP@ssw0rd.”)

My guess is that we’ll learn more during the coming days. But this should serve as a cautionary tale for anyone who is using the cloud: the cloud is another name for “someone else’s computer,” and you need to understand how much or how little you trust that computer.

If you’re changing password managers, look at my own Password Safe. Its main downside is that you can’t synch between devices, but that’s because I don’t use the cloud for anything.

News articles. Slashdot thread.

EDITED TO ADD: People choose lousy master passwords.

Posted on December 26, 2022 at 7:06 AM • View Comments

Apple Adds a Backdoor to iMessage and iCloud Storage

Apple’s announcement that it’s going to start scanning photos for child abuse material is a big deal. (Here are five news stories.) I have been following the details, and discussing it in several different email lists. I don’t have time right now to delve into the details, but wanted to post something.

EFF writes:

There are two main features that the company is planning to install in every Apple device. One is a scanning feature that will scan all photos as they get uploaded into iCloud Photos to see if they match a photo in the database of known child sexual abuse material (CSAM) maintained by the National Center for Missing & Exploited Children (NCMEC). The other feature scans all iMessage images sent or received by child accounts—that is, accounts designated as owned by a minor—for sexually explicit material, and if the child is young enough, notifies the parent when these images are sent or received. This feature can be turned on or off by parents.

This is pretty shocking coming from Apple, which is generally really good about privacy. It opens the door for all sorts of other surveillance, since now that the system is built it can be used for all sorts of other messages. And it breaks end-to-end encryption, despite Apple’s denials:

Does this break end-to-end encryption in Messages?

No. This doesn’t change the privacy assurances of Messages, and Apple never gains access to communications as a result of this feature. Any user of Messages, including those with with communication safety enabled, retains control over what is sent and to whom. If the feature is enabled for the child account, the device will evaluate images in Messages and present an intervention if the image is determined to be sexually explicit. For accounts of children age 12 and under, parents can set up parental notifications which will be sent if the child confirms and sends or views an image that has been determined to be sexually explicit. None of the communications, image evaluation, interventions, or notifications are available to Apple.

Notice Apple changing the definition of “end-to-end encryption.” No longer is the message a private communication between sender and receiver. A third party is alerted if the message meets a certain criteria.

This is a security disaster. Read tweets by Matthew Green and Edward Snowden. Also this. I’ll post more when I see it.

Beware the Four Horsemen of the Information Apocalypse. They’ll scare you into accepting all sorts of insecure systems.

EDITED TO ADD: This is a really good write-up of the problems.

EDITED TO ADD: Alex Stamos comments.

An open letter to Apple criticizing the project.

A leaked Apple memo responding to the criticisms. (What are the odds that Apple did not intend this to leak?)

EDITED TO ADD: John Gruber’s excellent analysis.

EDITED TO ADD (8/11): Paul Rosenzweig wrote an excellent policy discussion.

EDITED TO ADD (8/13): Really good essay by EFF’s Kurt Opsahl. Ross Anderson did an interview with Glenn Beck. And this news article talks about dissent within Apple about this feature.

The Economist has a good take. Apple responds to criticisms. (It’s worth watching the Wall Street Journal video interview as well.)