Entries Tagged "encryption"

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Security Analysis of Threema

A group of Swiss researchers have published an impressive security analysis of Threema.

We provide an extensive cryptographic analysis of Threema, a Swiss-based encrypted messaging application with more than 10 million users and 7000 corporate customers. We present seven different attacks against the protocol in three different threat models. As one example, we present a cross-protocol attack which breaks authentication in Threema and which exploits the lack of proper key separation between different sub-protocols. As another, we demonstrate a compression-based side-channel attack that recovers users’ long-term private keys through observation of the size of Threema encrypted back-ups. We discuss remediations for our attacks and draw three wider lessons for developers of secure protocols.

From a news article:

Threema has more than 10 million users, which include the Swiss government, the Swiss army, German Chancellor Olaf Scholz, and other politicians in that country. Threema developers advertise it as a more secure alternative to Meta’s WhatsApp messenger. It’s among the top Android apps for a fee-based category in Switzerland, Germany, Austria, Canada, and Australia. The app uses a custom-designed encryption protocol in contravention of established cryptographic norms.

The company is performing the usual denials and deflections:

In a web post, Threema officials said the vulnerabilities applied to an old protocol that’s no longer in use. It also said the researchers were overselling their findings.

“While some of the findings presented in the paper may be interesting from a theoretical standpoint, none of them ever had any considerable real-world impact,” the post stated. “Most assume extensive and unrealistic prerequisites that would have far greater consequences than the respective finding itself.”

Left out of the statement is that the protocol the researchers analyzed is old because they disclosed the vulnerabilities to Threema, and Threema updated it.

Posted on January 19, 2023 at 7:21 AMView Comments

ChatGPT-Written Malware

I don’t know how much of a thing this will end up being, but we are seeing ChatGPT-written malware in the wild.

…within a few weeks of ChatGPT going live, participants in cybercrime forums—­some with little or no coding experience­—were using it to write software and emails that could be used for espionage, ransomware, malicious spam, and other malicious tasks.

“It’s still too early to decide whether or not ChatGPT capabilities will become the new favorite tool for participants in the Dark Web,” company researchers wrote. “However, the cybercriminal community has already shown significant interest and are jumping into this latest trend to generate malicious code.”

Last month, one forum participant posted what they claimed was the first script they had written and credited the AI chatbot with providing a “nice [helping] hand to finish the script with a nice scope.”

The Python code combined various cryptographic functions, including code signing, encryption, and decryption. One part of the script generated a key using elliptic curve cryptography and the curve ed25519 for signing files. Another part used a hard-coded password to encrypt system files using the Blowfish and Twofish algorithms. A third used RSA keys and digital signatures, message signing, and the blake2 hash function to compare various files.

Check Point Research report.

ChatGPT-generated code isn’t that good, but it’s a start. And the technology will only get better. Where it matters here is that it gives less skilled hackers—script kiddies—new capabilities.

Posted on January 10, 2023 at 7:18 AMView Comments

Apple Is Finally Encrypting iCloud Backups

After way too many years, Apple is finally encrypting iCloud backups:

Based on a screenshot from Apple, these categories are covered when you flip on Advanced Data Protection: device backups, messages backups, iCloud Drive, Notes, Photos, Reminders, Safari bookmarks, Siri Shortcuts, Voice Memos, and Wallet Passes. Apple says the only “major” categories not covered by Advanced Data Protection are iCloud Mail, Contacts, and Calendar because “of the need to interoperate with the global email, contacts, and calendar systems,” according to its press release.

You can see the full list of data categories and what is protected under standard data protection, which is the default for your account, and Advanced Data Protection on Apple’s website.

With standard data protection, Apple holds the encryption keys for things that aren’t end-to-end encrypted, which means the company can help you recover that data if needed. Data that’s end-to-end encrypted can only be encrypted on “your trusted devices where you’re signed in with your Apple ID,” according to Apple, meaning that the company—or law enforcement or hackers—cannot access your data from Apple’s databases.

Note that this system doesn’t have the backdoor that was in Apple’s previous proposal, the one put there under the guise of detecting CSAM.

Apple says that it will roll out worldwide by the end of next year. I wonder how China will react to this.

Posted on December 12, 2022 at 7:00 AMView Comments

Charles V of Spain Secret Code Cracked

Diplomatic code cracked after 500 years:

In painstaking work backed by computers, Pierrot found “distinct families” of about 120 symbols used by Charles V. “Whole words are encrypted with a single symbol” and the emperor replaced vowels coming after consonants with marks, she said, an inspiration probably coming from Arabic.

In another obstacle, he used meaningless symbols to mislead any adversary trying to decipher the message.

The breakthrough came in June when Pierrot managed to make out a phrase in the letter, and the team then cracked the code with the help of Camille Desenclos, a historian. “It was painstaking and long work but there was really a breakthrough that happened in one day, where all of a sudden we had the right hypothesis,” she said.

Posted on November 29, 2022 at 7:19 AMView Comments

Breaking the Zeppelin Ransomware Encryption Scheme

Brian Krebs writes about how the Zeppelin ransomware encryption scheme was broken:

The researchers said their break came when they understood that while Zeppelin used three different types of encryption keys to encrypt files, they could undo the whole scheme by factoring or computing just one of them: An ephemeral RSA-512 public key that is randomly generated on each machine it infects.

“If we can recover the RSA-512 Public Key from the registry, we can crack it and get the 256-bit AES Key that encrypts the files!” they wrote. “The challenge was that they delete the [public key] once the files are fully encrypted. Memory analysis gave us about a 5-minute window after files were encrypted to retrieve this public key.”

Unit 221B ultimately built a “Live CD” version of Linux that victims could run on infected systems to extract that RSA-512 key. From there, they would load the keys into a cluster of 800 CPUs donated by hosting giant Digital Ocean that would then start cracking them. The company also used that same donated infrastructure to help victims decrypt their data using the recovered keys.

A company offered recovery services based on this break, but was reluctant to advertise because it didn’t want Zeppelin’s creators to fix their encryption flaw.

Technical details.

EDITED TO ADD (12/12): When BitDefender publicly advertised a decryption tool for a strain of DarkSide ransomware, DarkSide immediately updated its ransomware to render the tool obsolete. It’s hard to come up with a solution to this problem.

Posted on November 21, 2022 at 7:08 AMView Comments

Hyundai Uses Example Keys for Encryption System

This is a dumb crypto mistake I had not previously encountered:

A developer says it was possible to run their own software on the car infotainment hardware after discovering the vehicle’s manufacturer had secured its system using keys that were not only publicly known but had been lifted from programming examples.

[…]

“Turns out the [AES] encryption key in that script is the first AES 128-bit CBC example key listed in the NIST document SP800-38A [PDF]”.

[…]

Luck held out, in a way. “Greenluigi1” found within the firmware image the RSA public key used by the updater, and searched online for a portion of that key. The search results pointed to a common public key that shows up in online tutorials like “RSA Encryption & Decryption Example with OpenSSL in C.

EDITED TO ADD (8/23): Slashdot post.

Posted on August 22, 2022 at 6:38 AMView Comments

SIKE Broken

SIKE is one of the new algorithms that NIST recently added to the post-quantum cryptography competition.

It was just broken, really badly.

We present an efficient key recovery attack on the Supersingular Isogeny Diffie­-Hellman protocol (SIDH), based on a “glue-and-split” theorem due to Kani. Our attack exploits the existence of a small non-scalar endomorphism on the starting curve, and it also relies on the auxiliary torsion point information that Alice and Bob share during the protocol. Our Magma implementation breaks the instantiation SIKEp434, which aims at security level 1 of the Post-Quantum Cryptography standardization process currently ran by NIST, in about one hour on a single core.

News article.

Posted on August 4, 2022 at 6:56 AMView Comments

Facebook Is Now Encrypting Links to Prevent URL Stripping

Some sites, including Facebook, add parameters to the web address for tracking purposes. These parameters have no functionality that is relevant to the user, but sites rely on them to track users across pages and properties.

Mozilla introduced support for URL stripping in Firefox 102, which it launched in June 2022. Firefox removes tracking parameters from web addresses automatically, but only in private browsing mode or when the browser’s Tracking Protection feature is set to strict. Firefox users may enable URL stripping in all Firefox modes, but this requires manual configuration. Brave Browser strips known tracking parameters from web addresses as well.

Facebook has responded by encrypting the entire URL into a single ciphertext blob.

Since it is no longer possible to identify the tracking part of the web address, it is no longer possible to remove it from the address automatically. In other words: Facebook has the upper hand in regards to URL-based tracking at the time, and there is little that can be done about it short of finding a way to decrypt the information.

Posted on July 18, 2022 at 9:49 AMView Comments

NIST Announces First Four Quantum-Resistant Cryptographic Algorithms

NIST’s post-quantum computing cryptography standard process is entering its final phases. It announced the first four algorithms:

For general encryption, used when we access secure websites, NIST has selected the CRYSTALS-Kyber algorithm. Among its advantages are comparatively small encryption keys that two parties can exchange easily, as well as its speed of operation.

For digital signatures, often used when we need to verify identities during a digital transaction or to sign a document remotely, NIST has selected the three algorithms CRYSTALS-Dilithium, FALCON and SPHINCS+ (read as “Sphincs plus”). Reviewers noted the high efficiency of the first two, and NIST recommends CRYSTALS-Dilithium as the primary algorithm, with FALCON for applications that need smaller signatures than Dilithium can provide. The third, SPHINCS+, is somewhat larger and slower than the other two, but it is valuable as a backup for one chief reason: It is based on a different math approach than all three of NIST’s other selections.

NIST has not chosen a public-key encryption standard. The remaining candidates are BIKE, Classic McEliece, HQC, and SIKE.

I have a lot to say on this process, and have written an essay for IEEE Security & Privacy about it. It will be published in a month or so.

Posted on July 6, 2022 at 11:49 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.