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I recently wrote about the new iOS feature that forces an iPhone to reboot after it’s been inactive for a longish period of time.
Here are the technical details, discovered through reverse engineering. The feature triggers after seventy-two hours of inactivity, even it is remains connected to Wi-Fi.
Everybody is reporting about a new security iPhone security feature with iOS 18: if the phone hasn’t been used for a few days, it automatically goes into its “Before First Unlock” state and has to be rebooted.
This is a really good security feature. But various police departments don’t like it, because it makes it harder for them to unlock suspects’ phones.
Not a lot of details:
Apple has issued a new round of threat notifications to iPhone users across 98 countries, warning them of potential mercenary spyware attacks. It’s the second such alert campaign from the company this year, following a similar notification sent to users in 92 nations in April.
From Slashdot:
Apple and Google have launched a new industry standard called “Detecting Unwanted Location Trackers” to combat the misuse of Bluetooth trackers for stalking. Starting Monday, iPhone and Android users will receive alerts when an unknown Bluetooth device is detected moving with them. The move comes after numerous cases of trackers like Apple’s AirTags being used for malicious purposes.
Several Bluetooth tag companies have committed to making their future products compatible with the new standard. Apple and Google said they will continue collaborating with the Internet Engineering Task Force to further develop this technology and address the issue of unwanted tracking.
This seems like a good idea, but I worry about false alarms. If I am walking with a friend, will it alert if they have a Bluetooth tracking device in their pocket?
It’s yet another hardware side-channel attack:
The threat resides in the chips’ data memory-dependent prefetcher, a hardware optimization that predicts the memory addresses of data that running code is likely to access in the near future. By loading the contents into the CPU cache before it’s actually needed, the DMP, as the feature is abbreviated, reduces latency between the main memory and the CPU, a common bottleneck in modern computing. DMPs are a relatively new phenomenon found only in M-series chips and Intel’s 13th-generation Raptor Lake microarchitecture, although older forms of prefetchers have been common for years.
[…]
The breakthrough of the new research is that it exposes a previously overlooked behavior of DMPs in Apple silicon: Sometimes they confuse memory content, such as key material, with the pointer value that is used to load other data. As a result, the DMP often reads the data and attempts to treat it as an address to perform memory access. This “dereferencing” of “pointers”—meaning the reading of data and leaking it through a side channel—is a flagrant violation of the constant-time paradigm.
[…]
The attack, which the researchers have named GoFetch, uses an application that doesn’t require root access, only the same user privileges needed by most third-party applications installed on a macOS system. M-series chips are divided into what are known as clusters. The M1, for example, has two clusters: one containing four efficiency cores and the other four performance cores. As long as the GoFetch app and the targeted cryptography app are running on the same performance cluster—even when on separate cores within that cluster—GoFetch can mine enough secrets to leak a secret key.
The attack works against both classical encryption algorithms and a newer generation of encryption that has been hardened to withstand anticipated attacks from quantum computers. The GoFetch app requires less than an hour to extract a 2048-bit RSA key and a little over two hours to extract a 2048-bit Diffie-Hellman key. The attack takes 54 minutes to extract the material required to assemble a Kyber-512 key and about 10 hours for a Dilithium-2 key, not counting offline time needed to process the raw data.
The GoFetch app connects to the targeted app and feeds it inputs that it signs or decrypts. As its doing this, it extracts the app secret key that it uses to perform these cryptographic operations. This mechanism means the targeted app need not perform any cryptographic operations on its own during the collection period.
Note that exploiting the vulnerability requires running a malicious app on the target computer. So it could be worse. On the other hand, like many of these hardware side-channel attacks, it’s not possible to patch.
Slashdot thread.
Apple announced PQ3, its post-quantum encryption standard based on the Kyber secure key-encapsulation protocol, one of the post-quantum algorithms selected by NIST in 2022.
There’s a lot of detail in the Apple blog post, and more in Douglas Stabila’s security analysis.
I am of two minds about this. On the one hand, it’s probably premature to switch to any particular post-quantum algorithms. The mathematics of cryptanalysis for these lattice and other systems is still rapidly evolving, and we’re likely to break more of them—and learn a lot in the process—over the coming few years. But if you’re going to make the switch, this is an excellent choice. And Apple’s ability to do this so efficiently speaks well about its algorithmic agility, which is probably more important than its particular cryptographic design. And it is probably about the right time to worry about, and defend against, attackers who are storing encrypted messages in hopes of breaking them later on future quantum computers.
Apple is rolling out a new “Stolen Device Protection” feature that seems well thought out:
When Stolen Device Protection is turned on, Face ID or Touch ID authentication is required for additional actions, including viewing passwords or passkeys stored in iCloud Keychain, applying for a new Apple Card, turning off Lost Mode, erasing all content and settings, using payment methods saved in Safari, and more. No passcode fallback is available in the event that the user is unable to complete Face ID or Touch ID authentication.
For especially sensitive actions, including changing the password of the Apple ID account associated with the iPhone, the feature adds a security delay on top of biometric authentication. In these cases, the user must authenticate with Face ID or Touch ID, wait one hour, and authenticate with Face ID or Touch ID again. However, Apple said there will be no delay when the iPhone is in familiar locations, such as at home or work.
More details at the link.
Signal has had the ability to manually authenticate another account for years. iMessage is getting it:
The feature is called Contact Key Verification, and it does just what its name says: it lets you add a manual verification step in an iMessage conversation to confirm that the other person is who their device says they are. (SMS conversations lack any reliable method for verification—sorry, green-bubble friends.) Instead of relying on Apple to verify the other person’s identity using information stored securely on Apple’s servers, you and the other party read a short verification code to each other, either in person or on a phone call. Once you’ve validated the conversation, your devices maintain a chain of trust in which neither you nor the other person has given any private encryption information to each other or Apple. If anything changes in the encryption keys each of you verified, the Messages app will notice and provide an alert or warning.
The Flipper Zero is an incredibly versatile hacking device. Now it can be used to crash iPhones in its vicinity by sending them a never-ending stream of pop-ups.
These types of hacks have been possible for decades, but they require special equipment and a fair amount of expertise. The capabilities generally required expensive SDRs—short for software-defined radios—that, unlike traditional hardware-defined radios, use firmware and processors to digitally re-create radio signal transmissions and receptions. The $200 Flipper Zero isn’t an SDR in its own right, but as a software-controlled radio, it can do many of the same things at an affordable price and with a form factor that’s much more convenient than the previous generations of SDRs.
Apple has warned leaders of the opposition government in India that their phones are being spied on:
Multiple top leaders of India’s opposition parties and several journalists have received a notification from Apple, saying that “Apple believes you are being targeted by state-sponsored attackers who are trying to remotely compromise the iPhone associated with your Apple ID ….”
AccessNow puts this in context:
For India to uphold fundamental rights, authorities must initiate an immediate independent inquiry, implement a ban on the use of rights-abusing commercial spyware, and make a commitment to reform the country’s surveillance laws. These latest warnings build on repeated instances of cyber intrusion and spyware usage, and highlights the surveillance impunity in India that continues to flourish despite the public outcry triggered by the 2019 Pegasus Project revelations.
Sidebar photo of Bruce Schneier by Joe MacInnis.