LastPass Admits to Severe Data Breach, Encrypted Password Vaults Stolen

Dec 23, 2022Ravie LakshmananPassword Management / Data Breach

The August 2022 security breach^[1] of LastPass may have
been more severe than previously disclosed by the company.

The popular password management service on Thursday revealed
that malicious actors obtained a trove of personal information
belonging to its customers that include their encrypted password
vaults using data siphoned from the break-in.

Also stolen is “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
company said^[2].

The August 2022 incident, which remains^[3]
a subject of an ongoing investigation, involved the miscreants
accessing source code and proprietary technical information from
its development environment via a single compromised employee
account.

LastPass said this permitted the unidentified attacker to obtain
credentials and keys that were subsequently leveraged to extract
information from a backup stored in a cloud-based storage service,
which it emphasized is physically separate from its production
environment.

On top of that, the adversary is said to have copied customer
vault data from the encrypted storage service. It’s stored in a
“proprietary binary format” that contains both unencrypted data,
such as website URLs, and fully-encrypted fields like website
usernames and passwords, secure notes, and form-filled data.

These fields, the company explained, are protected using 256-bit
AES encryption and can be decoded only with a key derived from the
user’s master password^[4]
on the users’ devices.

LastPass confirmed that the security lapse did not involve
access to unencrypted credit card data, as this information was not
archived in the cloud storage container.

The company did not divulge how recent the backup was, but
warned that the threat actor “may attempt to use brute-force to
guess your master password and decrypt the copies of vault data
they took,” as well as target customers with social engineering and
credential stuffing attacks.

It bears noting at this stage that the success of the
brute-force attacks to predict the master passwords is inversely
proportional to their strength, meaning the easier it is to guess
the password, the lesser the number of attempts required to crack
it.

“If you reuse your master password and that password was ever
compromised, a threat actor may use dumps of compromised
credentials that are already available on the internet to attempt
to access your account,” LastPass cautioned.

The fact that website URLs are in plaintext means that a
successful decryption of the master password could give the
attackers a sense of the websites a particular user holds accounts
with, enabling them to mount additional phishing or credential
theft attacks.

The company further said that it notified a small subset of its
business customers – which amounts to less than 3% – to take
certain unspecified action based on their account
configurations.

The development comes days after Okta acknowledged^[5]
that threat actors gained unauthorized access to its Workforce
Identity Cloud (WIC) repositories hosted on GitHub and copied the
source code.