Last week, just before Christmas, LastPass dropped a bombshell announcement: as the result of a breach in August, which led to another breach in November, hackers had gotten their hands on users’ password vaults. While the company insists that your login information is still secure, some cybersecurity experts are heavily criticizing its post, saying that it could make people feel more secure than they actually are and pointing out that this is just the latest in a series of incidents that make it hard to trust the password manager.
LastPass’ December 22nd statement was “full of omissions, half-truths and outright lies,” reads a blog post from Wladimir Palant, a security researcher known for helping originally develop AdBlock Pro, among other things. Some of his criticisms deal with how the company has framed the incident and how transparent it’s being; he accuses the company of trying to portray the August incident where LastPass says “some source code and technical information were stolen” as a separate breach when he says that in reality the company “failed to contain” the breach.
He also highlights LastPass’ admission that the leaked data included “the IP addresses from which customers were accessing the LastPass service,” saying that could let the threat actor “create a complete movement profile” of customers if LastPass was logging every IP address you used with its service.
Another security researcher, Jeremi Gosney, wrote a long post on Mastodon explaining his recommendation to move to another password manager. “LastPass’s claim of ‘zero knowledge’ is a bald-faced lie,” he says, alleging that the company has “about as much knowledge as a password manager can possibly get away with.”
LastPass claims its “zero knowledge” architecture keeps users safe because the company never has access to your master password, which is the thing that hackers would need to unlock the stolen vaults. While Gosney doesn’t dispute that particular point, he does say that the phrase is misleading. “I think most people envision their vault as a sort of encrypted database where the entire file is protected, but no — with LastPass, your vault is a plaintext file and only a few select fields are encrypted.”
Palant also notes that the encryption only does you any good if the hackers can’t crack your master password, which is LastPass’ main defense in its post: if you use its defaults for password length and strengthening and haven’t reused it on another site, “it would take millions of years to guess your master password using generally-available password-cracking technology” wrote Karim Toubba, the company’s CEO.
“This prepares the ground for blaming the customers,” writes Palant, saying that “LastPass should be aware that passwords will be decrypted for at least some of their customers. And they have a convenient explanation already: these customers clearly didn’t follow their best practices.” However, he also points out that LastPass hasn’t necessarily enforced those standards. Despite the fact that it made 12-character passwords the default in 2018, Palant says, “I can log in with my eight-character password without any warnings or prompts to change it.”
LastPass’ post has even elicited a response from a competitor, 1Password — on Wednesday, the company’s principal security architect Jeffrey Goldberg wrote a post for its site titled “Not in a million years: It can take far less to crack a LastPass password.” In it, Goldberg calls LastPass’ claim of it taking a million years to crack a master password “highly misleading,” saying that the statistic appears to assume a 12 character, randomly generated password. “Passwords created by humans come nowhere near meeting that requirement,” he writes, saying that threat actors would be able to prioritize certain guesses based on how people construct passwords they can actually remember.
Of course, a competitor’s word should probably be taken with a grain of salt, though Palant echos a similar idea in his post — he claims the viral XKCD method of creating passwords would take around 3 years to guess with a single GPU, while some 11-character passwords (that many people may consider to be good) would only take around 25 minutes to crack with the same hardware. It goes without saying that a motivated actor trying to crack into a specific target’s vault could probably throw more than one GPU at the problem, potentially cutting that time down by orders of magnitude.
Both Gosney and Palant take issue with LastPass’ actual cryptography too, though for different reasons. Gosney accuses the company of basically committing “every ‘crypto 101’ sin” with how its encryption is implemented and how it manages data once it’s been loaded into your device’s memory.
Meanwhile, Palant criticizes the company’s post for painting its password-strengthening algorithm, known as PBKDF2, as “stronger-than-typical.” The idea behind the standard is that it makes it harder to brute-force guess your passwords, as you’d have to perform a certain number of calculations on each guess. “I seriously wonder what LastPass considers typical,” writes Palant, “given that 100,000 PBKDF2 iterations are the lowest number I’ve seen in any current password manager.”
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Robin Edgar
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